I can use array pointers as iterators in for_each but when I try to do the same using distance, the Solaris 12.4 compiler complains about not finding a match.
Here is my code:
#include <iterator>
#include <algorithm>
#include <iostream>
#include <iomanip>
using std::cout;
using std::endl;
using std::hex;
struct Bob {
char q[16];
};
Bob stuff[16];
void DoBob(Bob& bob) {
cout << "BOB! " << hex << &bob << endl;
}
int main() {
// int ret = std::distance(&stuff[0], &stuff[3]);
// The line above causes the Solaris C++ compiler to complain:
//"main.cc", line 22: Error: Could not find a match for std::distance<_ForwardIterator, _Distance>(Bob*, Bob*) needed in main().
std::for_each(&stuff[0], &stuff[3], DoBob);
return 0;
}
I tend not to like to blame the compiler. Am I doing something wrong or is this a problem with the Solaris compiler?
Related
I have received the following error for the following code on Visual Studio Code for Mac.
ArrayStudy.cpp:21:19: error: cannot deduce type of initializer list because std::initializer_list was not found; include <initializer_list>
for (auto x : {10,21,32,43,54,65})
I included #include <initializer_list> after noting it was absent, but continued to receive the error. I'm using Apple clang version 13.0.0 (clang-1300.0.29.30).
At this point I am stumped. Can someone help me get this code running with a short explanation of what I missed?
#include <iostream>
#include <string>
#include <fstream>
#include <initializer_list>
void print();
int main(){
print();
}
void print() {
int v[] = {0,1,2,3,4,5,6,7,8,9};
for (auto x : v)
cout << x << '\n';
for (auto x : {10,21,32,43,54,65})
cout << x << '\n';
}
I have a number of strings and their bitset equivalents. I need to be able to look up equivalents in both directions, i.e. "str to bitset" and "bitset to str". I believe boost-bimap would be the right container for this job.
I managed to get this to work with strings and integers but my string / bitset bimap does not compile. I am using VS2019 with the latest boost release.
Integer example works:
#include <boost/bimap.hpp>
#include <string>
#include <iostream>
int main()
{
typedef boost::bimap<std::string, int> bimap_str_int_t;
bimap_str_int_t bimap1;
bimap1.insert(bimap_str_int_t::value_type("A", 1));
std::cout << bimap1.left.at("A") << '\n'; //prints 1
std::cout << bimap1.right.at(1) << '\n'; // prints A
}
Bitset example fails to compile:
#include <boost/bimap.hpp>
#include <string>
#include <iostream>
#include <bitset>
int main()
{
typedef std::bitset<3> bitset_t;
typedef boost::bimap<std::string, bitset_t> bimap_str_bitset_t;
bimap_str_bitset_t bimap2;
bitset_t bits{ "010" };
bimap2.insert(bimap_str_bitset_t::value_type("A", bits));
std::cout << bimap2.left.at("A") << '\n';
std::cout << bimap2.right.at(bits) << '\n';
}
The bitset example creates the following compiler error:
boost_test.cpp(20): message : see reference to class template instantiation 'boost::bimaps::bimap' being compiled
I am not sure how to fix this and would greatly appreciate any hints.
The issue is that std::bitset has no operator< - one of the requirements of any STL-like ordered collection.
To fix this, you need to supply a comparison function - here's one way you might try:
#include <boost/bimap.hpp>
#include <string>
#include <iostream>
#include <bitset>
typedef std::bitset<3> bitset_t;
struct compare_bitset {
bool operator()(const bitset_t& x, const bitset_t& y) const {
return x.to_ulong() < y.to_ulong();
}
};
int main()
{
using bitset_set = boost::bimaps::set_of<bitset_t, compare_bitset>;
typedef boost::bimap < std::string, bitset_set> bimap_str_bitset_t;
bimap_str_bitset_t bimap2;
bitset_t bits{ "010" };
bimap2.insert(bimap_str_bitset_t::value_type("A", bits));
std::cout << bimap2.left.at("A") << '\n';
std::cout << bimap2.right.at(bits) << '\n';
}
Whenever I use std::string to declare a string variable in c++ it prevents the program from outputting anything. for example:
#include <cstdlib>
#include <iostream>
#include <string>
int main() {
std::cout << "Hello";
// std::string s;
return 0;
}
This will output Hello to the command-line as it should do.
#include <cstdlib>
#include <iostream>
#include <string>
int main() {
std::cout << "Hello";
std::string s;
return 0;
}
This will not output anything (and no errors) since i'm declaring a variable using std::string
I'm using the minGW compiler on a Windows 10 64bit machine
I am trying to learn C++, however, the parameter to a method I have in my own class is misbehaving. When it uses a dataType of 'int', it works fine with no errors, but when I attempt to change it to a 'string' dataType, the program crashes with this error.
Error 1 error C2061: syntax error : identifier 'string' in temp.h ln
8 col 1
The classes I am using are as follows:
WORKING CODE
TesterClass.cpp // Entry Point
#include "stdafx.h"
#include "Temp.h"
int _tmain(int argc, _TCHAR* argv[])
{
Temp tmp;
tmp.doSomething(7);
return 0;
}
Temp.h
#pragma once
class Temp
{
public:
Temp();
void doSomething(int blah);
};
Temp.cpp
#include "stdafx.h"
#include "Temp.h"
#include <iostream>
#include <string>
using std::string;
Temp::Temp()
{
std::cout << "Entry" << std::endl;
string hi;
std::cin >> hi;
std::cout << hi << std::endl;
}
void Temp::doSomething(int blah)
{
std::cout << blah;
}
BROKEN CODE
Temp.h
#pragma once
class Temp
{
public:
Temp();
void doSomething(string blah);
};
Temp.cpp
#include "stdafx.h"
#include "Temp.h"
#include <iostream>
#include <string>
using std::string;
Temp::Temp()
{
std::cout << "Entry" << std::endl;
string hi;
std::cin >> hi;
std::cout << hi << std::endl;
}
void Temp::doSomething(string blah)
{
std::cout << blah;
}
When I adjust the parameter 'blah' to be a string, in both the .h and .cpp file, the problem occurs.
I have looked around, but none of the answers seem to solve my problem. I would greatly love help on this an I am out of ideas. I have tried reinstalling C++, messing with:
using namepace std;
using std::string;
std::string instead of string
etc.
If you know how to solve my problem I would love to hear from you. I am more than happy to provide more information.
C++ performs single-pass compilation, so std::string needs to be declared before you use it at all - including in the header file.
// Temp.h
#pragma once
#include <string>
class Temp
{
public:
Temp();
void doSomething(std::string blah);
};
I would encourage you to be specific in your header files when specifying classes like this, because you might easily come across another library that defines it's own string and then you would run into naming conflicts. Save the using import statements for your cpp files.
πάντα ῥεῖ had the write answer, thankyou!
They said to use std::string when needed, and to also #include <string> in the header file.
The following code causes a C1001 internal error in Visual Studio 2013 (v12.0.30501.00 Update 2) - should I expect it to work? (downloadable here)
I was expecting to be able to call the func function without a vals argument and have the default of {10.0} used.
Any help appreciated!
C.hpp:
#include <string>
#include <initializer_list>
#pragma once
class C {
public:
void func(std::string str, std::initializer_list<double> vals = { 10.0 });
};
C.cpp:
#include "stdafx.h"
#include "C.hpp"
#include <iostream>
using namespace std;
void C::func(std::string str, std::initializer_list<double> vals){
cout << "str is " << str << endl;
for (double v : vals){
cout << v << endl;
}
}
initializer_list_default_parameter.cpp:
#include "stdafx.h"
#include "C.hpp"
int _tmain(int argc, _TCHAR* argv[])
{
C inst;
inst.func("name"); // this line causes a C1001 error with MSVC 2013
//inst.func("name", { 4.3 }); this line compiles
return 0;
}
Yes, initializer_list parameters can have default values, but there's a bug in the MSVC 2013 x86 compiler meaning they're not supported (http://connect.microsoft.com/VisualStudio/Feedback/details/925540).