Using overloaded operator+ without assignment - c++

I have simple(not simple) question: Is any possibility that overloaded operator+ will be working not as we want when we won't use assignment overloaded operator?
Example:
object a, b, c;
//Here is some code where I add some numbers to object a and b;
c=a+b;
cout << c;
And the thing is: when I'm using overloaded assingment operator, everything is fine. But without this, elements which are in c gets some random numbers. Why?
And another question: why I can't do something like that with overloaded << and + operators:
cout << a+b;
EDIT: Here is code:
#include <iostream>
#include <cstdio>
using namespace std;
class List;
class element{
private:
int number;
element* next;
friend class List;
friend ostream & operator<<(ostream &, List &);
public:
element(int data){
number=data;
}
int getData(){
return number;
}
};
class List{
private:
element* head;
int size;
friend ostream & operator<<(ostream &, List &);
public:
List(){
head=NULL;
size=0;
}
List(const List &lista){
//cout << "wyw" << endl;
//fflush(stdout);
if (lista.size==0){
size=0;
head=NULL;
}
else
{
size=0;
head=NULL;
element* tmp=lista.head;
while(tmp!=NULL){
cout << tmp->number << " ";
fflush(stdout);
this->addToList(tmp->number);
tmp=tmp->next;
}
}
}
~List(){
if (head!=NULL){
element* tmp=head;
element *temp;
while(tmp!=NULL){
temp=tmp->next;
delete tmp;
tmp=temp;
}
head=NULL;
}
}
void addToList(int data){
element* newNode=new element(data);
newNode->next=NULL;
element *tmp=head;
if (tmp!=NULL){
while(tmp->next!=NULL){
tmp=tmp->next;
}
tmp->next=newNode;
}
else{
head=newNode;
}
size++;
}
List& operator=(const List& lista){
if (&lista==this) return *this;
if (this->head!=NULL){
element* tmp=head;
element *temp;
while(tmp!=NULL){
temp=tmp->next;
delete tmp;
tmp=temp;
}
head=NULL;
}
if (lista.size==0){
size=0;
head=NULL;
}
else
{
size=0;
head=NULL;
element* tmp=lista.head;
while(tmp!=NULL){
this->addToList(tmp->number);
tmp=tmp->next;
}
}
return *this;
}
List operator+(const List &lista){
List newList;
element *tmp=this->head;
while (tmp!=NULL){
newList.addToList(tmp->number);
tmp=tmp->next;
}
tmp=lista.head;
while (tmp!=NULL){
newList.addToList(tmp->number);
tmp=tmp->next;
}
return newList;
}
};
istream & operator>>(istream &str, List &lists){
int data;
str >> data;
lists.addToList(data);
return str;
}
ostream & operator<<(ostream &str, List &lists){
element*tmp=lists.head;
if (tmp==NULL){
str << "List is empty" << endl;
}
else{
while(tmp!=NULL){
str << tmp->number << "--";
tmp=tmp->next;
}
str << "NULL" << endl << "Size of lsit: " << lists.size << endl;
}
return str;
}
int main(){
List lista;
cin >> lista;
cin >> lista;
List list2=lista;
cout << lista;
cout << list2;
List c;
//cout << list2+lista; CANT DO THAT, WHY?
c=list2+lista;
cout << c;
return 0;
}
#DrewDormann Here is error:
lista.cpp: In function ‘int main()’:
lista.cpp:167:7: error: no match for ‘operator<<’ (operand types are ‘std::ostream {aka std::basic_ostream<char>}’ and ‘List’)
cout << lista+list2;
^
lista.cpp:167:7: note: candidates are:
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:108:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ostream_type& (*)(std::basic_ostream<_CharT, _Traits>::__ostream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(__ostream_type& (*__pf)(__ostream_type&))
^
/usr/include/c++/4.8/ostream:108:7: note: no known conversion for argument 1 from ‘List’ to ‘std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&) {aka std::basic_ostream<char>& (*)(std::basic_ostream<char>&)}’
/usr/include/c++/4.8/ostream:117:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ios_type& (*)(std::basic_ostream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>; std::basic_ostream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
operator<<(__ios_type& (*__pf)(__ios_type&))
^
/usr/include/c++/4.8/ostream:117:7: note: no known conversion for argument 1 from ‘List’ to ‘std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}’
/usr/include/c++/4.8/ostream:127:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(ios_base& (*__pf) (ios_base&))
^
/usr/include/c++/4.8/ostream:127:7: note: no known conversion for argument 1 from ‘List’ to ‘std::ios_base& (*)(std::ios_base&)’
/usr/include/c++/4.8/ostream:166:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long __n)
^
/usr/include/c++/4.8/ostream:166:7: note: no known conversion for argument 1 from ‘List’ to ‘long int’
/usr/include/c++/4.8/ostream:170:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long __n)
^
/usr/include/c++/4.8/ostream:170:7: note: no known conversion for argument 1 from ‘List’ to ‘long unsigned int’
/usr/include/c++/4.8/ostream:174:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(bool __n)
^
/usr/include/c++/4.8/ostream:174:7: note: no known conversion for argument 1 from ‘List’ to ‘bool’
In file included from /usr/include/c++/4.8/ostream:609:0,
from /usr/include/c++/4.8/iostream:39,
from lista.cpp:1:
/usr/include/c++/4.8/bits/ostream.tcc:91:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.8/bits/ostream.tcc:91:5: note: no known conversion for argument 1 from ‘List’ to ‘short int’
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:181:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned short __n)
^
/usr/include/c++/4.8/ostream:181:7: note: no known conversion for argument 1 from ‘List’ to ‘short unsigned int’
In file included from /usr/include/c++/4.8/ostream:609:0,
from /usr/include/c++/4.8/iostream:39,
from lista.cpp:1:
/usr/include/c++/4.8/bits/ostream.tcc:105:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.8/bits/ostream.tcc:105:5: note: no known conversion for argument 1 from ‘List’ to ‘int’
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:192:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned int __n)
^
/usr/include/c++/4.8/ostream:192:7: note: no known conversion for argument 1 from ‘List’ to ‘unsigned int’
/usr/include/c++/4.8/ostream:201:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long long __n)
^
/usr/include/c++/4.8/ostream:201:7: note: no known conversion for argument 1 from ‘List’ to ‘long long int’
/usr/include/c++/4.8/ostream:205:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long long __n)
^
/usr/include/c++/4.8/ostream:205:7: note: no known conversion for argument 1 from ‘List’ to ‘long long unsigned int’
/usr/include/c++/4.8/ostream:220:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(double __f)
^
/usr/include/c++/4.8/ostream:220:7: note: no known conversion for argument 1 from ‘List’ to ‘double’
/usr/include/c++/4.8/ostream:224:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(float __f)
^
/usr/include/c++/4.8/ostream:224:7: note: no known conversion for argument 1 from ‘List’ to ‘float’
/usr/include/c++/4.8/ostream:232:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long double __f)
^
/usr/include/c++/4.8/ostream:232:7: note: no known conversion for argument 1 from ‘List’ to ‘long double’
/usr/include/c++/4.8/ostream:245:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(const void* __p)
^
/usr/include/c++/4.8/ostream:245:7: note: no known conversion for argument 1 from ‘List’ to ‘const void*’
In file included from /usr/include/c++/4.8/ostream:609:0,
from /usr/include/c++/4.8/iostream:39,
from lista.cpp:1:
/usr/include/c++/4.8/bits/ostream.tcc:119:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.8/bits/ostream.tcc:119:5: note: no known conversion for argument 1 from ‘List’ to ‘std::basic_ostream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}’
lista.cpp:141:12: note: std::ostream& operator<<(std::ostream&, List&)
ostream & operator<<(ostream &str, List &lists){
^
lista.cpp:141:12: note: no known conversion for argument 2 from ‘List’ to ‘List&’
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:548:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*)
operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
^
/usr/include/c++/4.8/ostream:548:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: cannot convert ‘List::operator+(const List&)((*(const List*)(& list2)))’ (type ‘List’) to type ‘const unsigned char*’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:543:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*)
operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
^
/usr/include/c++/4.8/ostream:543:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: cannot convert ‘List::operator+(const List&)((*(const List*)(& list2)))’ (type ‘List’) to type ‘const signed char*’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:530:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*)
operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
^
/usr/include/c++/4.8/ostream:530:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: cannot convert ‘List::operator+(const List&)((*(const List*)(& list2)))’ (type ‘List’) to type ‘const char*’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/ostream:609:0,
from /usr/include/c++/4.8/iostream:39,
from lista.cpp:1:
/usr/include/c++/4.8/bits/ostream.tcc:321:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s)
^
/usr/include/c++/4.8/bits/ostream.tcc:321:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: cannot convert ‘List::operator+(const List&)((*(const List*)(& list2)))’ (type ‘List’) to type ‘const char*’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:513:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
^
/usr/include/c++/4.8/ostream:513:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: mismatched types ‘const _CharT*’ and ‘List’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:493:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char)
operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
^
/usr/include/c++/4.8/ostream:493:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: cannot convert ‘List::operator+(const List&)((*(const List*)(& list2)))’ (type ‘List’) to type ‘unsigned char’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:488:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char)
operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
^
/usr/include/c++/4.8/ostream:488:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: cannot convert ‘List::operator+(const List&)((*(const List*)(& list2)))’ (type ‘List’) to type ‘signed char’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:482:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char)
operator<<(basic_ostream<char, _Traits>& __out, char __c)
^
/usr/include/c++/4.8/ostream:482:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: cannot convert ‘List::operator+(const List&)((*(const List*)(& list2)))’ (type ‘List’) to type ‘char’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:476:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char)
operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
^
/usr/include/c++/4.8/ostream:476:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: cannot convert ‘List::operator+(const List&)((*(const List*)(& list2)))’ (type ‘List’) to type ‘char’
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from lista.cpp:1:
/usr/include/c++/4.8/ostream:471:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT)
operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
^
/usr/include/c++/4.8/ostream:471:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: deduced conflicting types for parameter ‘_CharT’ (‘char’ and ‘List’)
cout << lista+list2;
^
In file included from /usr/include/c++/4.8/string:52:0,
from /usr/include/c++/4.8/bits/locale_classes.h:40,
from /usr/include/c++/4.8/bits/ios_base.h:41,
from /usr/include/c++/4.8/ios:42,
from /usr/include/c++/4.8/ostream:38,
from /usr/include/c++/4.8/iostream:39,
from lista.cpp:1:
/usr/include/c++/4.8/bits/basic_string.h:2753:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
operator<<(basic_ostream<_CharT, _Traits>& __os,
^
/usr/include/c++/4.8/bits/basic_string.h:2753:5: note: template argument deduction/substitution failed:
lista.cpp:167:16: note: ‘List’ is not derived from ‘const std::basic_string<_CharT, _Traits, _Alloc>’
cout << lista+list2;
I know that this is when i'm trying to use operaotr without overloading, but here problem is that operator << is overloaded.

Yes, it is possible.
For example: Imagine that both + and = operators also invert a number. If you invert twice - you get correct result. But if you invert it only once (e.g. using non-overloaded = operator) you get an unexpected result.
What is happening in your case - I have no idea. You provide not enough data for a more concrete and useful answer.

Related

c++: compilation errors with std::endl and operator>>

I was writing a simple piece of c++ code to print out input till the input is not 42. Here is my code:
#include <iostream>
using namespace std;
int main(){
while(true){
int inp;
cin >> inp >> endl;
if(inp == 42){
break;
}
cout << inp << endl;
}
return 0;
}
However when I compile it ,I get a list of errors:
testlife.cpp: In function ‘int main()’:
testlife.cpp:9:14: error: no match for ‘operator>>’ (operand types are ‘std::basic_istream<char>::__istream_type {aka std::basic_istream<char>}’ and ‘<unresolved overloaded function type>’)
cin >> inp >> endl;
~~~~~~~~~~~^~~~~~~
In file included from /usr/include/c++/6/iostream:40:0,
from testlife.cpp:2:
/usr/include/c++/6/istream:120:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(__istream_type& (*__pf)(__istream_type&))
^~~~~~~~
/usr/include/c++/6/istream:120:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&) {aka std::basic_istream<char>& (*)(std::basic_istream<char>&)}’
/usr/include/c++/6/istream:124:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__ios_type& (*)(std::basic_istream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>; std::basic_istream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
operator>>(__ios_type& (*__pf)(__ios_type&))
^~~~~~~~
/usr/include/c++/6/istream:124:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}’
/usr/include/c++/6/istream:131:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(ios_base& (*__pf)(ios_base&))
^~~~~~~~
/usr/include/c++/6/istream:131:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘std::ios_base& (*)(std::ios_base&)’
/usr/include/c++/6/istream:168:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(bool& __n)
^~~~~~~~
/usr/include/c++/6/istream:168:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘bool&’
/usr/include/c++/6/istream:172:7: note: candidate: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char; _Traits = std::char_traits<char>]
operator>>(short& __n);
^~~~~~~~
/usr/include/c++/6/istream:172:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘short int&’
/usr/include/c++/6/istream:175:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(unsigned short& __n)
^~~~~~~~
/usr/include/c++/6/istream:175:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘short unsigned int&’
/usr/include/c++/6/istream:179:7: note: candidate: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char; _Traits = std::char_traits<char>]
operator>>(int& __n);
^~~~~~~~
/usr/include/c++/6/istream:179:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘int&’
/usr/include/c++/6/istream:182:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(unsigned int& __n)
^~~~~~~~
/usr/include/c++/6/istream:182:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘unsigned int&’
/usr/include/c++/6/istream:186:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(long& __n)
^~~~~~~~
/usr/include/c++/6/istream:186:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long int&’
/usr/include/c++/6/istream:190:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(unsigned long& __n)
^~~~~~~~
/usr/include/c++/6/istream:190:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long unsigned int&’
/usr/include/c++/6/istream:195:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(long long& __n)
^~~~~~~~
/usr/include/c++/6/istream:195:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long long int&’
/usr/include/c++/6/istream:199:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(unsigned long long& __n)
^~~~~~~~
/usr/include/c++/6/istream:199:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long long unsigned int&’
/usr/include/c++/6/istream:214:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(float&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(float& __f)
^~~~~~~~
/usr/include/c++/6/istream:214:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘float&’
/usr/include/c++/6/istream:218:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(double&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(double& __f)
^~~~~~~~
/usr/include/c++/6/istream:218:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘double&’
/usr/include/c++/6/istream:222:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long double&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(long double& __f)
^~~~~~~~
/usr/include/c++/6/istream:222:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long double&’
/usr/include/c++/6/istream:235:7: note: candidate: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>]
operator>>(void*& __p)
^~~~~~~~
/usr/include/c++/6/istream:235:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘void*&’
/usr/include/c++/6/istream:259:7: note: candidate: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_istream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
operator>>(__streambuf_type* __sb);
^~~~~~~~
/usr/include/c++/6/istream:259:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘std::basic_istream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}’
In file included from /usr/include/c++/6/string:53:0,
from /usr/include/c++/6/bits/locale_classes.h:40,
from /usr/include/c++/6/bits/ios_base.h:41,
from /usr/include/c++/6/ios:42,
from /usr/include/c++/6/ostream:38,
from /usr/include/c++/6/iostream:39,
from testlife.cpp:2:
/usr/include/c++/6/bits/basic_string.tcc:1437:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)
operator>>(basic_istream<_CharT, _Traits>& __in,
^~~~~~~~
/usr/include/c++/6/bits/basic_string.tcc:1437:5: note: template argument deduction/substitution failed:
testlife.cpp:9:17: note: couldn't deduce template parameter ‘_Alloc’
cin >> inp >> endl;
^~~~
In file included from /usr/include/c++/6/iostream:40:0,
from testlife.cpp:2:
/usr/include/c++/6/istream:799:5: note: candidate: std::basic_istream<_CharT2, _Traits2>& std::operator>>(std::basic_istream<_CharT2, _Traits2>&, _CharT2*) [with _CharT2 = char; _Traits2 = std::char_traits<char>; _CharT = char; _Traits = std::char_traits<char>]
operator>>(basic_istream<char>& __in, char* __s);
^~~~~~~~
/usr/include/c++/6/istream:799:5: note: no known conversion for argument 2 from ‘<unresolved overloaded function type>’ to ‘char*’
In file included from /usr/include/c++/6/istream:934:0,
from /usr/include/c++/6/iostream:40,
from testlife.cpp:2:
/usr/include/c++/6/bits/istream.tcc:923:5: note: candidate: std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT&) [with _CharT = char; _Traits = std::char_traits<char>]
operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c)
^~~~~~~~
/usr/include/c++/6/bits/istream.tcc:923:5: note: no known conversion for argument 2 from ‘<unresolved overloaded function type>’ to ‘char&’
In file included from /usr/include/c++/6/iostream:40:0,
from testlife.cpp:2:
/usr/include/c++/6/istream:756:5: note: candidate: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char&)
operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c)
^~~~~~~~
/usr/include/c++/6/istream:756:5: note: template argument deduction/substitution failed:
testlife.cpp:9:17: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘unsigned char&’
cin >> inp >> endl;
^~~~
In file included from /usr/include/c++/6/iostream:40:0,
from testlife.cpp:2:
/usr/include/c++/6/istream:761:5: note: candidate: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char&)
operator>>(basic_istream<char, _Traits>& __in, signed char& __c)
^~~~~~~~
/usr/include/c++/6/istream:761:5: note: template argument deduction/substitution failed:
testlife.cpp:9:17: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘signed char&’
cin >> inp >> endl;
^~~~
In file included from /usr/include/c++/6/iostream:40:0,
from testlife.cpp:2:
/usr/include/c++/6/istream:803:5: note: candidate: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char*)
operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s)
^~~~~~~~
/usr/include/c++/6/istream:803:5: note: template argument deduction/substitution failed:
testlife.cpp:9:17: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘unsigned char*’
cin >> inp >> endl;
^~~~
In file included from /usr/include/c++/6/iostream:40:0,
from testlife.cpp:2:
/usr/include/c++/6/istream:808:5: note: candidate: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*)
operator>>(basic_istream<char, _Traits>& __in, signed char* __s)
^~~~~~~~
/usr/include/c++/6/istream:808:5: note: template argument deduction/substitution failed:
testlife.cpp:9:17: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘signed char*’
cin >> inp >> endl;
^~~~
In file included from /usr/include/c++/6/iostream:40:0,
from testlife.cpp:2:
/usr/include/c++/6/istream:924:5: note: candidate: template<class _CharT, class _Traits, class _Tp> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&&, _Tp&)
operator>>(basic_istream<_CharT, _Traits>&& __is, _Tp& __x)
^~~~~~~~
/usr/include/c++/6/istream:924:5: note: template argument deduction/substitution failed:
testlife.cpp:9:17: note: couldn't deduce template parameter ‘_Tp’
cin >> inp >> endl;
I have never encountered such error before nor I am unable to debug it given the simple block of code I am writing. I am using g++ compiler installed on ubuntu system.
Remove the endl from the cin statement:
cin >> inp;
Instead of:
cin >> inp >> endl;
There's no overload of the std::endl I/O manipulator for std::istream as the error message clearly states.
Also you should handle errors when taking input, otherwise your loop will run forever:
int main(){
while(true){
int inp;
if(cin >> inp && inp == 42) {
break;
}
else {
cin.clear();
cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
continue;
}
cout << inp << endl;
}
return 0;
}

trying to use vector<vector<int>> in a class

starting to learn classes in c++ and i came across a simple board game... but i got this insane amount of error that i cant solve.
if i shouldn't post this kind of question here, please advise me.
Board.h:
#include<vector>
using namespace std;
class Board{
int largura;
int altura;
public:
Board(int x,int y) : largura(x), altura(y) {}
vector<vector<int> > mat();
void printa();
};
Board.cpp:
#include "Board.h"
#include <vector>
#include <iostream>
using namespace std;
vector<vector<int> > Board::mat() {
vector<vector<int> > v(altura, vector<int>(largura,1));
return v;
}
void Board::printa() {
auto matriz = mat();
vector<int> vec(largura,0);
for(;;) {
for (auto i:vec) {
for (auto j:vec) {
cout << matriz[i,j];
}
cout << "\n";
}
}
}
main.cpp:
#include<iostream>
#include "Board.h"
#include <vector>
using namespace std;
int main(){
Board tela(5, 5);
tela.mat();
tela.printa();
return 0;
}
the error:
[Rafael#localhost untitled]$ g++ -std=c++17 main.cpp Board.cpp -o board
Board.cpp: In member function ‘void Board::printa()’:
Board.cpp:22:22: error: no match for ‘operator<<’ (operand types are ‘std::ostream {aka std::basic_ostream<char>}’ and ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’)
cout << matriz[i,j];
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:108:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ostream_type& (*)(std::basic_ostream<_CharT, _Traits>::__ostream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(__ostream_type& (*__pf)(__ostream_type&))
^~~~~~~~
/usr/include/c++/6.3.1/ostream:108:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&) {aka std::basic_ostream<char>& (*)(std::basic_ostream<char>&)}’
/usr/include/c++/6.3.1/ostream:117:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ios_type& (*)(std::basic_ostream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>; std::basic_ostream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
operator<<(__ios_type& (*__pf)(__ios_type&))
^~~~~~~~
/usr/include/c++/6.3.1/ostream:117:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}’
/usr/include/c++/6.3.1/ostream:127:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(ios_base& (*__pf) (ios_base&))
^~~~~~~~
/usr/include/c++/6.3.1/ostream:127:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘std::ios_base& (*)(std::ios_base&)’
/usr/include/c++/6.3.1/ostream:166:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long __n)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:166:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘long int’
/usr/include/c++/6.3.1/ostream:170:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long __n)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:170:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘long unsigned int’
/usr/include/c++/6.3.1/ostream:174:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(bool __n)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:174:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘bool’
In file included from /usr/include/c++/6.3.1/ostream:638:0,
from /usr/include/c++/6.3.1/iostream:39,
from Board.cpp:7:
/usr/include/c++/6.3.1/bits/ostream.tcc:91:5: note: candidate: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/6.3.1/bits/ostream.tcc:91:5: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘short int’
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:181:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned short __n)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:181:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘short unsigned int’
In file included from /usr/include/c++/6.3.1/ostream:638:0,
from /usr/include/c++/6.3.1/iostream:39,
from Board.cpp:7:
/usr/include/c++/6.3.1/bits/ostream.tcc:105:5: note: candidate: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/6.3.1/bits/ostream.tcc:105:5: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘int’
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:192:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned int __n)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:192:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘unsigned int’
/usr/include/c++/6.3.1/ostream:201:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long long __n)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:201:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘long long int’
/usr/include/c++/6.3.1/ostream:205:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long long __n)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:205:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘long long unsigned int’
/usr/include/c++/6.3.1/ostream:220:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(double __f)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:220:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘double’
/usr/include/c++/6.3.1/ostream:224:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(float __f)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:224:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘float’
/usr/include/c++/6.3.1/ostream:232:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long double __f)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:232:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘long double’
/usr/include/c++/6.3.1/ostream:245:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(const void* __p)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:245:7: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘const void*’
In file included from /usr/include/c++/6.3.1/ostream:638:0,
from /usr/include/c++/6.3.1/iostream:39,
from Board.cpp:7:
/usr/include/c++/6.3.1/bits/ostream.tcc:119:5: note: candidate: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
basic_ostream<_CharT, _Traits>::
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/6.3.1/bits/ostream.tcc:119:5: note: no known conversion for argument 1 from ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ to ‘std::basic_ostream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}’
In file included from /usr/include/c++/6.3.1/string:52:0,
from /usr/include/c++/6.3.1/bits/locale_classes.h:40,
from /usr/include/c++/6.3.1/bits/ios_base.h:41,
from /usr/include/c++/6.3.1/ios:42,
from /usr/include/c++/6.3.1/ostream:38,
from /usr/include/c++/6.3.1/iostream:39,
from Board.cpp:7:
/usr/include/c++/6.3.1/bits/basic_string.h:5325:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)
operator<<(basic_ostream<_CharT, _Traits>& __os,
^~~~~~~~
/usr/include/c++/6.3.1/bits/basic_string.h:5325:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’ is not derived from ‘const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/bits/ios_base.h:46:0,
from /usr/include/c++/6.3.1/ios:42,
from /usr/include/c++/6.3.1/ostream:38,
from /usr/include/c++/6.3.1/iostream:39,
from Board.cpp:7:
/usr/include/c++/6.3.1/system_error:209:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::error_code&)
operator<<(basic_ostream<_CharT, _Traits>& __os, const error_code& __e)
^~~~~~~~
/usr/include/c++/6.3.1/system_error:209:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘const std::error_code&’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:497:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT)
operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:497:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: deduced conflicting types for parameter ‘_CharT’ (‘char’ and ‘std::vector<int>’)
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:502:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char)
operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:502:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘char’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:508:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char)
operator<<(basic_ostream<char, _Traits>& __out, char __c)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:508:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘char’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:514:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char)
operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:514:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘signed char’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:519:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char)
operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:519:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘unsigned char’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:539:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:539:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: mismatched types ‘const _CharT*’ and ‘std::vector<int>’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/ostream:638:0,
from /usr/include/c++/6.3.1/iostream:39,
from Board.cpp:7:
/usr/include/c++/6.3.1/bits/ostream.tcc:321:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s)
^~~~~~~~
/usr/include/c++/6.3.1/bits/ostream.tcc:321:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘const char*’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:556:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*)
operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:556:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘const char*’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:569:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*)
operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:569:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘const signed char*’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:574:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*)
operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:574:5: note: template argument deduction/substitution failed:
Board.cpp:22:35: note: cannot convert ‘matriz.std::vector<_Tp, _Alloc>::operator[]<std::vector<int>, std::allocator<std::vector<int> > >(((void)0, ((std::vector<std::vector<int> >::size_type)j)))’ (type ‘__gnu_cxx::__alloc_traits<std::allocator<std::vector<int> > >::value_type {aka std::vector<int>}’) to type ‘const unsigned char*’
cout << matriz[i,j];
^
In file included from /usr/include/c++/6.3.1/iostream:39:0,
from Board.cpp:7:
/usr/include/c++/6.3.1/ostream:628:5: note: candidate: std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&&, const _Tp&) [with _CharT = char; _Traits = std::char_traits<char>; _Tp = std::vector<int>] <near match>
operator<<(basic_ostream<_CharT, _Traits>&& __os, const _Tp& __x)
^~~~~~~~
/usr/include/c++/6.3.1/ostream:628:5: note: conversion of argument 1 would be ill-formed:
Board.cpp:22:35: error: cannot bind ‘std::ostream {aka std::basic_ostream<char>}’ lvalue to ‘std::basic_ostream<char>&&’
cout << matriz[i,j];
[i,j] is a trap. It's the same thing as [j]. What you want is matriz[i][j];, not matriz[i,j].
(You should also avoid using directives in header files, but that's purely cosmetic. Your problem is the [i,j] part.)

overload ostream::<< to print vector of vectors

Working off Chris's answer in this post How to print out the contents of a vector? I am trying to overload ostream << to print a vector vectors. Here's what I'm reading in from a file, where each line becomes a vector:
1, 2, 3
4, 4, 4, 4, 4
7, 7
41, 52, 632
So the structure looks something like
v[0] = [1, 2, 3]
and so on.
I thought Chris's solution should apply perfectly to this situation, and it certainly works for a 1d vector, but I'm trying to understand why it doesn't work for a 2d vector. The code's below:
template <typename T>
std::ostream& operator << (std::ostream& out, const std::vector<T>& v){
if(! v.empty()){
std::cout<< '[';
std::copy(v.begin(), v.end(), std::ostream_iterator<T>(std::cout, " "));
std::cout<< ']' << std::endl;
}
else{
std::cout << "[ ]" << std::endl;
}
}
I'm thinking I need to replace the function in std::ostream_iterator to be << since that is what I am overriding in the first place, but I have tried << and ostream::<< and std:: << and these all yield compile-time errors. What would be the proper way to do this?
If I try to run the code above as is on a vector of vectors of ints, I have the following compile-time error:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h: In instantiation of ‘std::ostream_iterator<_Tp, _CharT, _Traits>& std::ostream_iterator<_Tp, _CharT, _Traits>::operator=(const _Tp&) [with _Tp = std::vector<int>; _CharT = char; _Traits = std::char_traits<char>]’:
/usr/include/c++/4.9/bits/stl_algobase.h:336:18: required from ‘static _OI std::__copy_move<false, false, std::random_access_iterator_tag>::__copy_m(_II, _II, _OI) [with _II = const std::vector<int>*; _OI = std::ostream_iterator<std::vector<int>, char, std::char_traits<char> >]’
/usr/include/c++/4.9/bits/stl_algobase.h:396:70: required from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = const std::vector<int>*; _OI = std::ostream_iterator<std::vector<int>, char, std::char_traits<char> >]’
/usr/include/c++/4.9/bits/stl_algobase.h:434:38: required from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = __gnu_cxx::__normal_iterator<const std::vector<int>*, std::vector<std::vector<int> > >; _OI = std::ostream_iterator<std::vector<int>, char, std::char_traits<char> >]’
/usr/include/c++/4.9/bits/stl_algobase.h:466:17: required from ‘_OI std::copy(_II, _II, _OI) [with _II = __gnu_cxx::__normal_iterator<const std::vector<int>*, std::vector<std::vector<int> > >; _OI = std::ostream_iterator<std::vector<int>, char, std::char_traits<char> >]’
ctest.cpp:15:75: required from ‘std::ostream& operator<<(std::ostream&, const std::vector<T>&) [with T = std::vector<int>; std::ostream = std::basic_ostream<char>]’
ctest.cpp:70:18: required from here
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: error: no match for ‘operator<<’ (operand types are ‘std::ostream_iterator<std::vector<int>, char, std::char_traits<char> >::ostream_type {aka std::basic_ostream<char>}’ and ‘const std::vector<int>’)
*_M_stream << __value;
^
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: candidates are:
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:108:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ostream_type& (*)(std::basic_ostream<_CharT, _Traits>::__ostream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(__ostream_type& (*__pf)(__ostream_type&))
^
/usr/include/c++/4.9/ostream:108:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&) {aka std::basic_ostream<char>& (*)(std::basic_ostream<char>&)}’
/usr/include/c++/4.9/ostream:117:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ios_type& (*)(std::basic_ostream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>; std::basic_ostream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
operator<<(__ios_type& (*__pf)(__ios_type&))
^
/usr/include/c++/4.9/ostream:117:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}’
/usr/include/c++/4.9/ostream:127:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(ios_base& (*__pf) (ios_base&))
^
/usr/include/c++/4.9/ostream:127:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘std::ios_base& (*)(std::ios_base&)’
/usr/include/c++/4.9/ostream:166:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long __n)
^
/usr/include/c++/4.9/ostream:166:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘long int’
/usr/include/c++/4.9/ostream:170:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long __n)
^
/usr/include/c++/4.9/ostream:170:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘long unsigned int’
/usr/include/c++/4.9/ostream:174:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(bool __n)
^
/usr/include/c++/4.9/ostream:174:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘bool’
In file included from /usr/include/c++/4.9/ostream:612:0,
from /usr/include/c++/4.9/iostream:39,
from ctest.cpp:1:
/usr/include/c++/4.9/bits/ostream.tcc:91:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.9/bits/ostream.tcc:91:5: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘short int’
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:181:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned short __n)
^
/usr/include/c++/4.9/ostream:181:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘short unsigned int’
In file included from /usr/include/c++/4.9/ostream:612:0,
from /usr/include/c++/4.9/iostream:39,
from ctest.cpp:1:
/usr/include/c++/4.9/bits/ostream.tcc:105:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.9/bits/ostream.tcc:105:5: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘int’
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:192:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned int __n)
^
/usr/include/c++/4.9/ostream:192:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘unsigned int’
/usr/include/c++/4.9/ostream:201:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long long __n)
^
/usr/include/c++/4.9/ostream:201:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘long long int’
/usr/include/c++/4.9/ostream:205:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long long __n)
^
/usr/include/c++/4.9/ostream:205:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘long long unsigned int’
/usr/include/c++/4.9/ostream:220:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(double __f)
^
/usr/include/c++/4.9/ostream:220:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘double’
/usr/include/c++/4.9/ostream:224:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(float __f)
^
/usr/include/c++/4.9/ostream:224:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘float’
/usr/include/c++/4.9/ostream:232:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long double __f)
^
/usr/include/c++/4.9/ostream:232:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘long double’
/usr/include/c++/4.9/ostream:245:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(const void* __p)
^
/usr/include/c++/4.9/ostream:245:7: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘const void*’
In file included from /usr/include/c++/4.9/ostream:612:0,
from /usr/include/c++/4.9/iostream:39,
from ctest.cpp:1:
/usr/include/c++/4.9/bits/ostream.tcc:119:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.9/bits/ostream.tcc:119:5: note: no known conversion for argument 1 from ‘const std::vector<int>’ to ‘std::basic_ostream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}’
In file included from /usr/include/c++/4.9/string:52:0,
from /usr/include/c++/4.9/bits/locale_classes.h:40,
from /usr/include/c++/4.9/bits/ios_base.h:41,
from /usr/include/c++/4.9/ios:42,
from /usr/include/c++/4.9/ostream:38,
from /usr/include/c++/4.9/iostream:39,
from ctest.cpp:1:
/usr/include/c++/4.9/bits/basic_string.h:2772:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
operator<<(basic_ostream<_CharT, _Traits>& __os,
^
/usr/include/c++/4.9/bits/basic_string.h:2772:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: ‘const std::vector<int>’ is not derived from ‘const std::basic_string<_CharT, _Traits, _Alloc>’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:471:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT)
operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
^
/usr/include/c++/4.9/ostream:471:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: deduced conflicting types for parameter ‘_CharT’ (‘char’ and ‘std::vector<int>’)
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:476:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char)
operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
^
/usr/include/c++/4.9/ostream:476:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: cannot convert ‘__value’ (type ‘const std::vector<int>’) to type ‘char’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:482:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char)
operator<<(basic_ostream<char, _Traits>& __out, char __c)
^
/usr/include/c++/4.9/ostream:482:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: cannot convert ‘__value’ (type ‘const std::vector<int>’) to type ‘char’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:488:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char)
operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
^
/usr/include/c++/4.9/ostream:488:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: cannot convert ‘__value’ (type ‘const std::vector<int>’) to type ‘signed char’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:493:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char)
operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
^
/usr/include/c++/4.9/ostream:493:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: cannot convert ‘__value’ (type ‘const std::vector<int>’) to type ‘unsigned char’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:513:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
^
/usr/include/c++/4.9/ostream:513:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: mismatched types ‘const _CharT*’ and ‘std::vector<int>’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/ostream:612:0,
from /usr/include/c++/4.9/iostream:39,
from ctest.cpp:1:
/usr/include/c++/4.9/bits/ostream.tcc:321:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s)
^
/usr/include/c++/4.9/bits/ostream.tcc:321:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: cannot convert ‘__value’ (type ‘const std::vector<int>’) to type ‘const char*’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:530:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*)
operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
^
/usr/include/c++/4.9/ostream:530:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: cannot convert ‘__value’ (type ‘const std::vector<int>’) to type ‘const char*’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:543:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*)
operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
^
/usr/include/c++/4.9/ostream:543:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: cannot convert ‘__value’ (type ‘const std::vector<int>’) to type ‘const signed char*’
*_M_stream << __value;
^
In file included from /usr/include/c++/4.9/iostream:39:0,
from ctest.cpp:1:
/usr/include/c++/4.9/ostream:548:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*)
operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
^
/usr/include/c++/4.9/ostream:548:5: note: template argument deduction/substitution failed:
In file included from /usr/include/c++/4.9/iterator:66:0,
from ctest.cpp:6:
/usr/include/c++/4.9/bits/stream_iterator.h:198:13: note: cannot convert ‘__value’ (type ‘const std::vector<int>’) to type ‘const unsigned char*’
*_M_stream << __value;
^
And this is the full file:
template <typename T>
std::ostream& operator << (std::ostream& out, const std::vector<T>& v){
if(! v.empty()){
std::cout<< '[';
std::copy(v.begin(), v.end(), std::ostream_iterator<T>(std::cout, " "));
std::cout<< ']' << std::endl;
}
else{
std::cout << "[ ]" << std::endl;
}
}
int main()
{
std::ifstream infile("filetest.txt");
std::string output;
std::string line;
std::vector<std::vector<int> > vec;
while(std::getline(infile, line))
{
std::vector<int> subvec;
int i;
std::istringstream iss(line);
while(iss >> i)
{
subvec.push_back(i);
if(iss.peek()==','|| iss.peek()== ' ')
iss.ignore();
}
std::cout << subvec;
vec.push_back(subvec);
}
std::cout << vec;
}
It depends heavily upon how you want your output formatted. You can just use the operator as-is, and it'll work (though you may or may not like the formatting):
#include <vector>
using std::vector;
#include <iostream>
using std::ostream;
template<typename T>
ostream& operator<< (ostream& out, const vector<T>& v) {
out << "[";
size_t last = v.size() - 1;
for (size_t i = 0; i < v.size(); ++i) {
out << v[i];
if (i != last)
out << ", ";
}
out << "]";
return out;
}
int main() {
std::vector<std::vector<int> > x { { 1, 2, 3 }, { 4, 5, 6 } };
std::cout << x;
}
Produces:
[[1, 2, 3], [4, 5, 6]]
Things only get more difficult if you need/want to change the formatting between one instance and another, such as having commas between the numbers, and new-lines between the rows. This is somewhat non-trivial to solve well, but I'll leave it at this for now, since it's not at all clear you really even want that.
This idea uses std::enable_if to iterate through members of what we choose to define as is_container. I wrote the code more out of curiosity than out of practicality though.
#include <iostream>
#include <type_traits>
#include <vector>
// by default you declare that no type is a container
template<typename T>
struct is_container {
static constexpr bool value = false;
};
// then you specify which types are actually containers.. I'm just declaring
// std::vector<T, A>, but you could make a similar declaration for list, array,
// and so on.
template<typename T, typename Allocator>
struct is_container<std::vector<T, Allocator> > {
static constexpr bool value = true;
};
// then you enable a print function to print all elements in a container (you
// can modify the actual formatting to your liking)
template<typename T>
typename std::enable_if<
is_container<T>::value,
std::ostream& >::type
inline operator<<(std::ostream& os, const T& container) {
const auto N = container.size();
std::size_t current = 0;
os << "[";
for(const auto & item : container) {
const char* separator = current++ == N - 1 ? "" : ", ";
os << item << separator;
}
os << "]";
return os;
}
// then the code will work for any level of nesting
int main() {
int scalar = 1;
std::cout << "Scalar: " << scalar << std::endl;
std::vector<int> vector {1, 2, 3, 4};
std::cout << "Vector: " << vector << std::endl;
std::vector< std::vector<int> > vvector {
{1, 2, 3, 4},
{5, 6, 7},
{8, 9, 10, 11, 12}
};
std::cout << "Vector<Vector>: " << vvector << std::endl;
std::vector< std::vector< std::vector<int> > > vvvector {
{
{1, 2, 3, 4},
{5, 6, 7},
{8, 9, 10, 11, 12}
},
{
{-1, -2, -3, -4},
{-5, -6, -7},
{-8, -9, -10}
}
};
std::cout << "Vector<Vector<Vector>>: " << vvvector << std::endl;
// you get the idea...
return 0;
}
Sample run:
$ g++ example.cpp -std=c++14 -Wall -Wextra -O3
$ ./a.out
Scalar: 1
Vector: [1, 2, 3, 4]
Vector<Vector>: [[1, 2, 3, 4], [5, 6, 7], [8, 9, 10, 11, 12]]
Vector<Vector<Vector>>: [[[1, 2, 3, 4], [5, 6, 7], [8, 9, 10, 11, 12]], [[-1, -2, -3, -4], [-5, -6, -7], [-8, -9, -10]]]

Why this template recursion won't compile?

I am attempting to print out the numbers from 1 to 1000 in C++ without any control statements or conditionals. I have found this question + answer on SO, but I cannot compile it on Linux with gcc 4.8. Any ideas why this is not working?
This is the code I'm trying:
#include <iostream>
template<int N>
struct NumberGeneration{
static void out(std::ostream& os)
{
NumberGeneration<N-1>::out(os);
os << N << std::endl;
}
};
template<>
struct NumberGeneration<1>{
static void out(std::ostream& os)
{
os << 1 << std::endl;
}
};
int main(){
NumberGeneration<1000>::out(std::cout);
}
The error I get is this:
main2.cpp:9:34: error: template instantiation depth exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum) instantiating ‘struct NumberGeneration<100>’
NumberGeneration<N-1>::out(os);
^
main2.cpp:9:34: recursively required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 999; std::ostream = std::basic_ostream<char>]’
main2.cpp:9:34: required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 1000; std::ostream = std::basic_ostream<char>]’
main2.cpp:21:28: required from here
main2.cpp:9:34: error: incomplete type ‘NumberGeneration<100>’ used in nested name specifier
main2.cpp:10:8: error: template instantiation depth exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting ‘template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char) [with _CharT = char; _Traits = std::char_traits<char>]’
os << N << std::endl;
^
main2.cpp:9:34: recursively required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 999; std::ostream = std::basic_ostream<char>]’
main2.cpp:9:34: required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 1000; std::ostream = std::basic_ostream<char>]’
main2.cpp:21:28: required from here
main2.cpp:10:8: error: template instantiation depth exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting ‘template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char) [with _Traits = std::char_traits<char>]’
main2.cpp:9:34: recursively required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 999; std::ostream = std::basic_ostream<char>]’
main2.cpp:9:34: required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 1000; std::ostream = std::basic_ostream<char>]’
main2.cpp:21:28: required from here
main2.cpp:10:8: error: template instantiation depth exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting ‘template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char) [with _Traits = std::char_traits<char>]’
main2.cpp:9:34: recursively required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 999; std::ostream = std::basic_ostream<char>]’
main2.cpp:9:34: required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 1000; std::ostream = std::basic_ostream<char>]’
main2.cpp:21:28: required from here
main2.cpp:10:8: error: template instantiation depth exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting ‘template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char) [with _Traits = std::char_traits<char>]’
main2.cpp:9:34: recursively required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 999; std::ostream = std::basic_ostream<char>]’
main2.cpp:9:34: required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 1000; std::ostream = std::basic_ostream<char>]’
main2.cpp:21:28: required from here
main2.cpp:10:13: error: template instantiation depth exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting ‘template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT) [with _CharT = char; _Traits = std::char_traits<char>]’
os << N << std::endl;
^
main2.cpp:9:34: recursively required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 999; std::ostream = std::basic_ostream<char>]’
main2.cpp:9:34: required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 1000; std::ostream = std::basic_ostream<char>]’
main2.cpp:21:28: required from here
main2.cpp:10:13: error: template instantiation depth exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting ‘template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>]’
main2.cpp:9:34: recursively required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 999; std::ostream = std::basic_ostream<char>]’
main2.cpp:9:34: required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 1000; std::ostream = std::basic_ostream<char>]’
main2.cpp:21:28: required from here
main2.cpp:10:13: error: template instantiation depth exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting ‘template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::endl(std::basic_ostream<_CharT, _Traits>&) [with _CharT = char; _Traits = std::char_traits<char>]’
main2.cpp:9:34: recursively required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 999; std::ostream = std::basic_ostream<char>]’
main2.cpp:9:34: required from ‘static void NumberGeneration<N>::out(std::ostream&) [with int N = 1000; std::ostream = std::basic_ostream<char>]’
main2.cpp:21:28: required from here
main2.cpp:10:13: error: no match for ‘operator<<’ (operand types are ‘std::basic_ostream<char>’ and ‘<unresolved overloaded function type>’)
main2.cpp:10:13: note: candidates are:
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:108:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ostream_type& (*)(std::basic_ostream<_CharT, _Traits>::__ostream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(__ostream_type& (*__pf)(__ostream_type&))
^
/usr/include/c++/4.8/ostream:108:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&) {aka std::basic_ostream<char>& (*)(std::basic_ostream<char>&)}’
/usr/include/c++/4.8/ostream:117:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ios_type& (*)(std::basic_ostream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>; std::basic_ostream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
operator<<(__ios_type& (*__pf)(__ios_type&))
^
/usr/include/c++/4.8/ostream:117:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}’
/usr/include/c++/4.8/ostream:127:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(ios_base& (*__pf) (ios_base&))
^
/usr/include/c++/4.8/ostream:127:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘std::ios_base& (*)(std::ios_base&)’
/usr/include/c++/4.8/ostream:166:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long __n)
^
/usr/include/c++/4.8/ostream:166:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long int’
/usr/include/c++/4.8/ostream:170:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long __n)
^
/usr/include/c++/4.8/ostream:170:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long unsigned int’
/usr/include/c++/4.8/ostream:174:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(bool __n)
^
/usr/include/c++/4.8/ostream:174:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘bool’
In file included from /usr/include/c++/4.8/ostream:609:0,
from /usr/include/c++/4.8/iostream:39,
from main2.cpp:1:
/usr/include/c++/4.8/bits/ostream.tcc:91:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.8/bits/ostream.tcc:91:5: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘short int’
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:181:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned short __n)
^
/usr/include/c++/4.8/ostream:181:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘short unsigned int’
In file included from /usr/include/c++/4.8/ostream:609:0,
from /usr/include/c++/4.8/iostream:39,
from main2.cpp:1:
/usr/include/c++/4.8/bits/ostream.tcc:105:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.8/bits/ostream.tcc:105:5: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘int’
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:192:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned int __n)
^
/usr/include/c++/4.8/ostream:192:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘unsigned int’
/usr/include/c++/4.8/ostream:201:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long long __n)
^
/usr/include/c++/4.8/ostream:201:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long long int’
/usr/include/c++/4.8/ostream:205:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long long __n)
^
/usr/include/c++/4.8/ostream:205:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long long unsigned int’
/usr/include/c++/4.8/ostream:220:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(double __f)
^
/usr/include/c++/4.8/ostream:220:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘double’
/usr/include/c++/4.8/ostream:224:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(float __f)
^
/usr/include/c++/4.8/ostream:224:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘float’
/usr/include/c++/4.8/ostream:232:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long double __f)
^
/usr/include/c++/4.8/ostream:232:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘long double’
/usr/include/c++/4.8/ostream:245:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(const void* __p)
^
/usr/include/c++/4.8/ostream:245:7: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘const void*’
In file included from /usr/include/c++/4.8/ostream:609:0,
from /usr/include/c++/4.8/iostream:39,
from main2.cpp:1:
/usr/include/c++/4.8/bits/ostream.tcc:119:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
basic_ostream<_CharT, _Traits>::
^
/usr/include/c++/4.8/bits/ostream.tcc:119:5: note: no known conversion for argument 1 from ‘<unresolved overloaded function type>’ to ‘std::basic_ostream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}’
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:548:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*)
operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
^
/usr/include/c++/4.8/ostream:548:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘const unsigned char*’
os << N << std::endl;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:543:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*)
operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
^
/usr/include/c++/4.8/ostream:543:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘const signed char*’
os << N << std::endl;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:530:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*)
operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
^
/usr/include/c++/4.8/ostream:530:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘const char*’
os << N << std::endl;
^
In file included from /usr/include/c++/4.8/ostream:609:0,
from /usr/include/c++/4.8/iostream:39,
from main2.cpp:1:
/usr/include/c++/4.8/bits/ostream.tcc:321:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s)
^
/usr/include/c++/4.8/bits/ostream.tcc:321:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘const char*’
os << N << std::endl;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:513:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
^
/usr/include/c++/4.8/ostream:513:5: note: substitution of deduced template arguments resulted in errors seen above
/usr/include/c++/4.8/ostream:493:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char)
operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
^
/usr/include/c++/4.8/ostream:493:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘unsigned char’
os << N << std::endl;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:488:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char)
operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
^
/usr/include/c++/4.8/ostream:488:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘signed char’
os << N << std::endl;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:482:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char)
operator<<(basic_ostream<char, _Traits>& __out, char __c)
^
/usr/include/c++/4.8/ostream:482:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘char’
os << N << std::endl;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:476:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char)
operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
^
/usr/include/c++/4.8/ostream:476:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: cannot convert ‘std::endl’ (type ‘<unresolved overloaded function type>’) to type ‘char’
os << N << std::endl;
^
In file included from /usr/include/c++/4.8/iostream:39:0,
from main2.cpp:1:
/usr/include/c++/4.8/ostream:471:5: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT)
operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
^
/usr/include/c++/4.8/ostream:471:5: note: substitution of deduced template arguments resulted in errors seen above
In file included from /usr/include/c++/4.8/string:52:0,
from /usr/include/c++/4.8/bits/locale_classes.h:40,
from /usr/include/c++/4.8/bits/ios_base.h:41,
from /usr/include/c++/4.8/ios:42,
from /usr/include/c++/4.8/ostream:38,
from /usr/include/c++/4.8/iostream:39,
from main2.cpp:1:
/usr/include/c++/4.8/bits/basic_string.h:2753:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
operator<<(basic_ostream<_CharT, _Traits>& __os,
^
/usr/include/c++/4.8/bits/basic_string.h:2753:5: note: template argument deduction/substitution failed:
main2.cpp:10:13: note: couldn't deduce template parameter ‘_Alloc’
os << N << std::endl;
^
And when I increase template instantiation depth I get :
$ gcc -Wall -ftemplate-depth=1100 -omain2 main2.cpp
/tmp/ccI81cmF.o: In function `main':
main2.cpp:(.text+0x5): undefined reference to `std::cout'
/tmp/ccI81cmF.o: In function `__static_initialization_and_destruction_0(int, int)':
main2.cpp:(.text+0x38): undefined reference to `std::ios_base::Init::Init()'
main2.cpp:(.text+0x47): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccI81cmF.o: In function `NumberGeneration<1>::out(std::ostream&)':
main2.cpp:(.text._ZN16NumberGenerationILi1EE3outERSo[_ZN16NumberGenerationILi1EE3outERSo]+0x19): undefined reference to `std::ostream::operator<<(int)'
main2.cpp:(.text._ZN16NumberGenerationILi1EE3outERSo[_ZN16NumberGenerationILi1EE3outERSo]+0x1e): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
main2.cpp:(.text._ZN16NumberGenerationILi1EE3outERSo[_ZN16NumberGenerationILi1EE3outERSo]+0x26): undefined reference to `std::ostream::operator<<(std::ostream& (*)(std::ostream&))'
/tmp/ccI81cmF.o: In function `NumberGeneration<1000>::out(std::ostream&)':
main2.cpp:(.text._ZN16NumberGenerationILi1000EE3outERSo[_ZN16NumberGenerationILi1000EE3outERSo]+0x25): undefined reference to `std::ostream::operator<<(int)'
main2.cpp:(.text._ZN16NumberGenerationILi1000EE3outERSo[_ZN16NumberGenerationILi1000EE3outERSo]+0x2a): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
main2.cpp:(.text._ZN16NumberGenerationILi1000EE3outERSo[_ZN16NumberGenerationILi1000EE3outERSo]+0x32): undefined reference to `std::ostream::operator<<(std::ostream& (*)(std::ostream&))'
As state in the comment, you reach the template depth limit, and use the wrong compiler:
so use a C++ compiler as g++
And then you may pass this argument to increase depth limit -depth=1000
or you may instantiate intermediate template as
template struct NumberGeneration<500>;
or rewrite your template to not use a depth linear with N
something like the following
// index_sequence and make_index_sequence available in C++14, but not in C++11
template <std::size_t...> struct index_sequence {};
namespace detail
{
template <typename, typename> struct concat;
template <std::size_t... Is1, std::size_t... Is2>
struct concat<index_sequence<Is1...>, index_sequence<Is2...>> :
index_sequence<Is1..., (sizeof...(Is1) + Is2)...>
{
using type = index_sequence<Is1..., (sizeof...(Is1) + Is2)...>;
};
}
template <std::size_t N>
struct make_index_sequence :
detail::concat<typename make_index_sequence<N / 2>::type,
typename make_index_sequence<N - N / 2>::type>::type
{
using type = typename
detail::concat<typename make_index_sequence<N / 2>::type,
typename make_index_sequence<N - N / 2>::type>::type;
};
template <>
struct make_index_sequence<1u> : index_sequence<0u> {
using type = index_sequence<0u>;
};
template <>
struct make_index_sequence<0u> : index_sequence<> {
using type = index_sequence<>;
};
And then with variadic template:
template<int N>
struct NumberGeneration{
static void out(std::ostream& os)
{
out(make_index_sequence<N>(), os);
}
private:
template<std::size_t ...Is>
static void out(index_sequence<Is...>, std::ostream& os)
{
std::initializer_list<int>{ ((os << (1 + Is) << std::endl), void(), 0)...};
}
};
Live example
The big problem is that it is really bad C++. It has a 1000 deep template instantiation depth, and the C++11 standard only advises 900. What more, there is little to no need for something that deep to do such a simple task.
Most compilers have template instantiation depth modification flags that make it larger. That is, however, a patch over the problem. The right way to fix that code is to either not write it, or decrease the depth.
#include <iostream>
template<int Max, unsigned Count=Max>
struct NumberGeneration{
void operator()(std::ostream& os) const
{
NumberGeneration<Max, (Count+1)/2>()(os);
NumberGeneration<Max-(Count+1)/2, (Count)/2>()(os);
}
};
template<int Max>
struct NumberGeneration<Max, 1>{
void operator()(std::ostream& os) const
{
os << Max << std::endl;
}
};
// not required:
template<int Max>
struct NumberGeneration<Max, 0>{
void operator()(std::ostream& os) const
{}
};
int main(){
NumberGeneration<1000>()(std::cout);
}
This now has a recursive template instantiation depth of about 10 instead of 1000, and is nearly as simple as the original version. I simply replaced single recursion with divide-and-conquer.
In C++14, efficient lists of integers via std::integral_sequence exist, and allow the above kind of thing even easier.
I also made NumberGeneration<X> into a stateless invokable type instead of having a static void out() method.

Compile error Message [duplicate]

This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Boolean and Void problem
So I have this code that has a sum function that sums n elements in a vector
C++ Syntax (Toggle Plain Text)
#include <iostream>
#include <vector> // need this in order to use vectors in the program
using namespace std;
void computeSum (vector<int> &Vec, int howMany, int total, bool success)
//the computeSum function that will sum positive numbers in a vector
{
int j;
total=0;
for(j=0;j < howMany;j++)
if (Vec[j] > 0){
total+=Vec[j];
} else {
total+=Vec[j+1];
}
if (howMany > Vec[j])
success = false;
else
success = true;
if (total != 0)
success = true;
if (success=true){
cout << total;
} else {
cout << "Oops! Appears you cannot add up these numbers!";
}
}
int main()
{
vector<int> dataVec;
bool success;
int i, n, howMany, total;
cout << "How many numbers would you like to put into the vector? \n";
cin >> n;
dataVec.resize(n);
for(vector<int>::size_type i=0;i < n;i++)
{
cout << "Enter your number for " << i+1 << ": \n";
cin >> dataVec[i];
}
cout << "How many POSITIVE numbers would you like to sum? \n";
cin >> howMany;
cout << "Your total is " << computeSum(dataVec, howMany, total, success);
}
Now before I added the
C++ Syntax (Toggle Plain Text)
bool success;
in the main() - the only error I had was success not declared in main - so now I declared it and I get this...
g++ -I/usr/local/include/bjarne/GUI -I -Wall -O3 -DNDEBUG -Wno-deprecated proj1.cc -o proj1
proj1.cc: In function ‘int main()’:
proj1.cc:59:76: error: no match for ‘operator<<’ in ‘std::operator<< [with _Traits = std::char_traits<char>]((* & std::cout), ((const char*)"Your total is ")) << computeSum((* & dataVec), howMany, total, ((int)success))’
proj1.cc:59:76: note: candidates are:
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:110:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ostream_type& (*)(std::basic_ostream<_CharT, _Traits>::__ostream_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:110:7: note: no known conversion for argument 1 from ‘void’ to ‘std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&)’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:119:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ios_type& (*)(std::basic_ostream<_CharT, _Traits>::__ios_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>, std::basic_ostream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:119:7: note: no known conversion for argument 1 from ‘void’ to ‘std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&)’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:129:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:129:7: note: no known conversion for argument 1 from ‘void’ to ‘std::ios_base& (*)(std::ios_base&)’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:167:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:167:7: note: no known conversion for argument 1 from ‘void’ to ‘long int’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:171:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:171:7: note: no known conversion for argument 1 from ‘void’ to ‘long unsigned int’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:175:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:175:7: note: no known conversion for argument 1 from ‘void’ to ‘bool’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:93:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:93:5: note: no known conversion for argument 1 from ‘void’ to ‘short int’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:182:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:182:7: note: no known conversion for argument 1 from ‘void’ to ‘short unsigned int’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:107:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char, _Traits = std::char_traits<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:107:5: note: no known conversion for argument 1 from ‘void’ to ‘int’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:193:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:193:7: note: no known conversion for argument 1 from ‘void’ to ‘unsigned int’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:202:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:202:7: note: no known conversion for argument 1 from ‘void’ to ‘long long int’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:206:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:206:7: note: no known conversion for argument 1 from ‘void’ to ‘long long unsigned int’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:211:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:211:7: note: no known conversion for argument 1 from ‘void’ to ‘double’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:215:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:215:7: note: no known conversion for argument 1 from ‘void’ to ‘float’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:223:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:223:7: note: no known conversion for argument 1 from ‘void’ to ‘long double’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:227:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:227:7: note: no known conversion for argument 1 from ‘void’ to ‘const void*’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:121:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:121:5: note: no known conversion for argument 1 from ‘void’ to ‘std::basic_ostream<char>::__streambuf_type*’
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/basic_string.h:2694:59: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:451:65: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:456:63: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:462:61: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:468:68: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:473:70: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:493:72: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/bits/ostream.tcc:323:70: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:510:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:523:75: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*)
/usr/lib/gcc/i686-redhat-linux/4.6.0/../../../../include/c++/4.6.0/ostream:528:77: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*)
make: *** [proj1] Error 1
....What?
**I even added a return at the end of the int main (( return 0;)) and still am getting the am error
You are trying to cout the return value of computeSum which is void. You can't cout << void.
/* computeSum returns void! */
cout << "Your total is " << computeSum(dataVec, howMany, total, success);
There are quite a few issues with the program as it turns out. I tried to cover everything, but I may have missed some. And because I blabber on and on it's a bit long.
The issue that's giving you the error message is to do with the return type of computeSum(). Right now the return type of computeSum() is void (ie it won't return anything), but in the line where the error occurs you are trying to print whatever is returned by computeSum().
It seems to me like you want 'total' to be returned by computeSum(), not given as a parameter. To do that, instead of making 'total' a parameter declare it at the start of computeSum(), and at the very end of the function add the line
return total;
So computeSum() should look like this:
int computeSum(vector<int> &Vec, int howMany, bool success)
{
int total = 0;
//...
return total;
}
There is also a logic error with the adding up part - think what happens when there are two negative numbers in a row for example.
Here is a better version:
int total = 0;
int i = 0; //the index of the current item being looked at
int numAddedUp = 0; //the number of positive numbers seen
//loop while need to add up more numbers AND i is within the bounds of Vect
//so stop upon reaching end of Vect even if not added up 'howMany' items yet.
while (numAdded < howMany && i < Vect.size())
{
if (Vect[i] > 0)
{
//if it's positive, add it
total += Vect[i];
numAddedUp++;
}
i++;
}
The logic of 'success' seems flimsy to me. If you use the while loop I suggested, you can use this instead:
if (numAddedUp == howMany)
{
success = true;
}
else
{
success = false;
}
or more briefly,
success = (numAddedUp == howMany);
You could extend the check for detecting special cases such as when howMany is less than one. The following line checks that howMany is valid AND the number of items added up matches howMany:
success = (howMany >= 1) && (numAddedUp == howMany);
Also watch out for the line
if (success=true){
which is assigning (=) the value true to 'success', but what you want to do is check for equality (==).
Finally, think about the way you are printing the output. Right now both main() and computeSum() are printing stuff. Ideally, computeSum() wouldn't print anything and the total would be returned along with a bool indicating success/failure. However, a much easier (but not good practice) approach would be to have computeSum() print the output and not even bother returning anything. The main() method would simply have to call the function like this:
computeSum(dataVec, howMany);
as the output will be printed in computeSum() along with nice, detailed, user-friendly error messages such as "The program is not working. Live with it." or "You broke the program!".