How would one would approach a situation where you want to output character per character in a C++ Program, to simulate a typing action?
Try this: (C++11)
#include <iostream>
#include <thread>
#include <chrono>
int main() {
std::string s = "Hello!";
for (const auto c : s) {
std::cout << c << std::flush;
std::this_thread::sleep_for(std::chrono::milliseconds(500));
}
std::cout << std::endl;
}
You can still use the usleep(ms) function from lib C, between each character you want to write. It works.
Related
An assignment wants me to make a function that makes all lowercase characters uppercase.
Here's my code:
main.cpp:
#include <iostream>
#include "Function.h"//Includes function file in main file
using namespace std;
int main(){
char a;
cout<<"Enter some words:";
cin.get(a);//Collects info from user
strcap(a);
cout<<a;
}
function.cpp:
#include <iostream>
#include "Function.h"
using namespace std;
char strcap(char a){
while (a!='\n'){
if (a>='a' && a<='z'){
a-=32;//
}
cin.get(a); //get the next letter
}
}
function.h:
#include <iostream>
char strcap(char a);
While the approach you have taken approximates a standard C approach, you have not provided adequate storage to read more than a single character. You could wrap your cin.get(a); strcap(a); cout << a; in a while loop, that would be an approach that is about a decade out of place in C++. Using std::basic::string provides automatic memory management for your input and std::transform makes it simple to apply a transformation to all elements of a container.
The example for std::transform provides exactly what you need, but it doesn't explain how to split the operation up into a separate header and source file. If after reading the documentation you are still stuck, the you can do something similar to the following.
Your header for function.h as you have it simply needs to provide for the declaration of strcap, e.g.
#include <string>
void strcap (std::string& s);
Your implementation for function.cpp likewise just needs to provide for the definition of strcap:
#include <cctype>
#include <algorithm>
#include "function.h"
void strcap (std::string& s)
{
std::transform (s.begin(), s.end(), s.begin(),
[](unsigned char c) -> unsigned char { return std::toupper(c); });
}
(note: the trailing-return-type "-> unsigned char" can be omitted above and it will be deduced properly)
Your main.cpp would then be:
#include <iostream>
#include "function.h"
int main (void) {
std::string s;
std::cout << "enter string: ";
if (getline (std::cin, s)) {
strcap(s);
std::cout << s << '\n';
}
}
Example Use/Output
Compile as you normally would, but you will require the language standard of at least -std=c++11, and then, e.g.
$ ./main
enter string: My dog has fleas
MY DOG HAS FLEAS
Also note, if you do not want to use std::transform, you can use a range-based-for loop to iterate over each character in your string converting to uppercase as well. Your strcap() function would then be:
void strcap (std::string& s)
{
for (auto& c : s)
c = toupper(c);
}
And if for some reason your compiler doesn't support the range-based for loop, then you can also use basic std::string:iterator to iterate over the string providing the conversion, e.g.
void strcap (std::string& s)
{
for (std::string::iterator it = s.begin(); it != s.end(); it++)
*it = toupper(*it);
}
There are several different approaches you can take.
Look things over and let me know if you have any further questions.
Code::Blocks Compiler Options
Just to make sure we are on the same sheet of paper, you should see:
My code is as follows.
#include "test.h"
#include "string"
#include "iostream"
using namespace std::string::find;
test::test(){
string str ("ffs test ffs");
string str2 ("test");
if (str.find(str2) != std::string::npos) {
std::cout << "found" << "\n";
} else {
std::cout << "not found" << "\n";
}
}
the issue I'm having is this, when trying to define a string in the C++ file qt states "unknown type name 'string'". Also on line 4 my 'import' highlights string as if it doesn't exist, despite it being an option the editor suggests to me while I'm typing it. What am I doing wrong here? Everything I find is to try and fix issues passing stuff to QStrings and nothing related to my issue as far as I can tell. I've tried both types of importing #include <thing> and #include "thing" on all the imports it doesn't seem to make a difference.
Use std::string instead of string.
#include "test.h"
#include <string>
#include <iostream>
test::test(){
std::string str ("ffs test ffs");
std::string str2 ("test");
if (str.find(str2) != std::string::npos) {
std::cout << "found" << "\n";
} else {
str::cout << "not found" << "\n";
}
}
Don't use using namespace (of course in your case, it wasn't a namespace, so that's another error), use <> for system headers.
After inclusion of the appropriate headers iostream, string etc, you can write:
using std::string;
This will bring in only string from the namespace std into your program.
And you can do this if you want to avoid typing std::string everywhere. You can do this for stream objects like cout, cin as well.
using std::cout;
using std::cin;
Use Scope operator :: in Your Code and Access manually to std class
std::string
it will help you !
So I recently discovered the use of map and vectors, however, I'm having trouble of trying to figure a way to loop through a vector containing strings.
Here's what I've tried:
#include <string>
#include <vector>
#include <stdio>
using namespace std;
void main() {
vector<string> data={"Hello World!","Goodbye World!"};
for (vector<string>::iterator t=data.begin(); t!=data.end(); ++t) {
cout<<*t<<endl;
}
}
and when I try to compile it, I get this error:
cd C:\Users\Jason\Desktop\EXB\Win32
wmake -f C:\Users\Jason\Desktop\EXB\Win32\exbint.mk -h -e
wpp386 ..\Source\exbint.cpp -i="C:\WATCOM/h;C:\WATCOM/h/nt" -w4 -e25 -zq -od -d2 -6r -bt=nt -fo=.obj -mf -xs -xr
..\Source\exbint.cpp(59): Error! E157: col(21) left expression must be integral
..\Source\exbint.cpp(59): Note! N717: col(21) left operand type is 'std::ostream watcall (lvalue)'
..\Source\exbint.cpp(59): Note! N718: col(21) right operand type is 'std::basic_string<char,std::char_traits<char>,std::allocator<char>> (lvalue)'
Error(E42): Last command making (C:\Users\Jason\Desktop\EXB\Win32\exbint.obj) returned a bad status
Error(E02): Make execution terminated
Execution complete
I tried the same method using map and it worked. The only difference was I changed the cout line to:
cout<<t->first<<" => "<<t->last<<endl;
Add iostream header file and change stdio to cstdio.
#include <iostream>
#include <string>
#include <vector>
#include <cstdio>
using namespace std;
int main()
{
vector<string> data={"Hello World!","Goodbye World!"};
for (vector<string>::iterator t=data.begin(); t!=data.end(); ++t)
{
cout<<*t<<endl;
}
return 0;
}
#include <iostream>
#include <vector>
#include <string>
int main()
{
std::vector<std::string> data = {"Hello World!", "Goodbye World!"};
for (std::vector<std::string>::iterator t = data.begin(); t != data.end(); t++) {
std::cout << *t << std::endl;
}
return 0;
}
Or with C++11 (or higher):
#include <iostream>
#include <vector>
#include <string>
typedef std::vector<std::string> STRVEC;
int main()
{
STRVEC data = {"Hello World!", "Goodbye World!"};
for (auto &s: data) {
std::cout << s << std::endl;
}
return 0;
}
From the Open Watcom V2 Fork-Wiki on the C++ Library Status page:
<string>
Mostly complete. Although there are no I/O operators, all other member functions and string operations are available.
A workaround (besides implementing the << operator) would be asking the string instances for the C string:
for (vector<string>::iterator t = data.begin(); t != data.end(); ++t) {
cout << t->c_str() << endl;
}
This of course only works as long as the strings don't contain zero byte values.
When I compile your code, I get:
40234801.cpp:3:17: fatal error: stdio: No such file or directory
#include <stdio>
^
You clearly have a header called "stdio" in your include path that you haven't shown us.
If you change that line to the standard #include <iostream>, then the only reported error is that you wrote void main() instead of int main(). Fix that, and it will build and run.
In passing, note also that using namespace should be avoided.
I found a solution to my own issue. Instead of using a c_str, I used std::string and switched to using the G++ compiler instead of Open Watcom
Instead of having:
char *someString="Blah blah blah";
I instead replaced it with:
string someString="Blah blah blah";
This way is much more efficient and easier.
I was trying to play around with Strings in a Hangman program that I'm writing and couldn't get them to work so tried working with them on a simpler basis and I'm still having no luck.
As far as I've read online in the references and what other people have said this code should work:
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;
int main (int argc, char** argv){
string word = {"Hello"};
int length = strlen(word);
}
But I get this compiler error:
'string' was not declared in this scope
and consequently, 'word' is also not declared in scope.
Can anyone see what I'm doing wrong? I'm using the g++ compiler on Ubuntu if that makes a difference, no idea which version though.
You are confusing C and C++.
You included only C libraries, whereas std::string comes from the C++ header string. You'd have to write:
#include <string>
to use it. However, you'd then have to make other changes, such as not using strlen.
You should learn from your C++ book, not random posts on the internet (#lolirony)
C version
#include <string.h>
int main(void)
{
const char* word = "Hello";
const size_t length = strlen(word); // `size_t` is more appropriate than `int`
return 0;
}
C-like C++ version
#include <cstring>
using namespace std;
int main()
{
const char* word = "Hello";
const size_t length = strlen(word);
}
Idiomatic C++ version (recommended)
#include <string>
int main()
{
const std::string word = "Hello";
const std::size_t length = word.size();
}
'string' was not declared in this scope
You need to include the header <string> and refer to it as std::string. Also, strlen does not understand std::string or any user defined types, but you can use the size() method instead:
#include <string>
int main()
{
std::string word = "Hello";
size_t length = word.size();
}
<cstring> is the header for C++ support of C-style null-terminated strings. You should include <string>.
You haven't included the C++ string header in your project.
#include <string>
The libraries that you've included are all plain-C headers.
Additionally, strlen() doesn't work with a c++ string; you should use word.size() instead.
string is a specialization of standard class std::basic_string . It is declared in header <string>
So if you want "to play around with standard class std::string:" you need to include directive
#include <string>
Header <cstring> is not the same as header <string> and contains declarations of standard C functions such as strlen.
However there is no any sense to apply function strlen to an object of type std::string The compiler in this case will issue an error.
I advice you to play with the following code that to see the difference
#include <iostream>
#include <string>
#include <cstring>
int main (int argc, char** argv)
{
std::string word = "Hello";
std::string::size_type length = word.length();
std::cout << "Object word of type std::string has value "
<< word << " with length of " << length
<< std::endl;
std::cout << "The size of the object itself is " << sizeof( word ) << std::endl;
char another_word[] = "Hello";
size_t another_length = std::strlen( another_word );
std::cout << "Object another_word of type char [6] has value "
<< another_word << " with length of " << another_length
<< std::endl;
std::cout << "The size of the object itself is " << sizeof( another_word ) << std::endl;
}
I have a std::string such as 20040531, I want to format this as 2004.05.31.
Apart from the straight forward way of doing an std::insert at respective locations, is there a better way to do this using Boost?
PS. I cannot use other Boost calls to get date/time as this string is returned via a custom API. So this question is reduced to basic string formatting which may not sound exciting, but I am trying to learn Boost.
You could use boost::format...
#include <string>
#include "boost/format.hpp"
#include <iostream>
int main()
{
std::string a("20040531");
std::cout << boost::format("%1%.%2%.%3%")
% a.substr(0,4) % a.substr(4,2) % a.substr(6,2);
}
You specifically asked about doing this using Boost, but if you wanted to do this in C++ without introducing a dependency on Boost then you could just use a stream to achieve the same thing:
#include <sstream>
#include <string>
#include <iostream>
int main()
{
std::stringstream s;
std::string a("20040531");
s << a.substr(0,4) << '.' << a.substr(4,2) << '.' << a.substr(6,2);
std::cout << s.str();
}