where is cout in Qt Creator

[hqking1988]

hi,i'm new in Qt.i use Qt Creator on Windows,but i get a problem here:
After i type in : cout << "hello world",where did it come out? i can't see it.why didn't it like visual c++ just poping a window which claimed "hello world" cheerfully?

[saa7_go]

You can replace cout with qDebug(),

#include <QDebug>
 
qDebug() << "Hello World";

#include <QDebug>

qDebug() << "Hello World";

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The output will be showed in the Application Output.

[tbscope]

No, that won't work either. All output is directed to stdout (or stderr), but a Qt Windows program never opens a console window unless you add a configuration option.

Add CONFIG += console in your .pro file
This will open a console window when you start your program.

[saa7_go]

No, that won't work either. All output is directed to stdout (or stderr), but a Qt Windows program never opens a console window unless you add a configuration option.

If you use gui module, and include QApplication header, the output from qDebug() will be showed in the Application Output (in Qt Creator).

Add CONFIG += console in your .pro file
This will open a console window when you start your program.

The problem is when you don't use event loop, console window will close immediately (when using Qt Creator). In windows, i usually add CONFIG += console in my .pro and the following line

#include <iostream>
#include <cstdlib>
 
using namespace std;
 
int main(int argc, char *argv[])
{
    cout << "Hello World!" << endl;
    system("PAUSE"); // <---
    return 0;
}

#include <iostream>
#include <cstdlib>

using namespace std;

int main(int argc, char *argv[])
{
    cout << "Hello World!" << endl;
    system("PAUSE"); // <---
    return 0;
}

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[pervlad]

QTextStream can be used too.

QTextStream out(stdout);
out << QString("Some text");

QTextStream out(stdout);
out << QString("Some text");

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[hqking1988]

thank you for your advice,it works out

[Ahmed Abdellatif]

it depending on what is the type of your app, console app or gui app. if it was console it would be appeared on console application but if you were using a gui, it should be appeared in the application output only when using

qDebug()<<"hello world";

[RandyBonnette]

Hello,

I've been using Qt4 and C++ for making programs in computer graphics, now switching to Gt5. How can I use 'cout' to print the variables in the console at run-time? It doesn't work, even when I add the libraries. Here's the error message: error: ‘cout’ was not declared in this scope



https://stackoverflow.com/questions/3886105/how-to-print-to-console-when-using-qt https://writemyessaytoday.net/write-my-essay-in-6-hours https://www.qtcentre.org/threads/33506-where-is-cout-in-Qt-Creator

[d_stranz]

cout is declared in the C++ Standard Library. You need to #include <iostream> and preface cout with the std:: scope:

std::cout << "Hello world!" <<std::endl;

std::cout << "Hello world!" <<std::endl;

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Or (bad practice) add a "using namespace std;" declaration after including iostream.