Qt Console Application - Print colored text

AliReza Beytari

Hey guys!
I want to print colored text in a Qt Console Application. This is what I wrote:

main.cpp:

#include <QCoreApplication>
#include "helper.h"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    Helper h;

    h.print("print: Hello World\n");
    h.printInfo("printInfo: Hello World\n");
    h.printWarning("printWarning: Hello World\n");
    h.printError("printError: Hello World\n");

    return a.exec();
}

helper.h:

#ifndef HELPER_H
#define HELPER_H

#include <QDebug>
#include <QTextStream>

class Helper
{
public:
    Helper();
    void print(QString str);
    void printInfo(QString str);
    void printWarning(QString str);
    void printError(QString str);
};

#endif // HELPER_H

helper.cpp:

#include "helper.h"

Helper::Helper()
{

}

void Helper::print(QString str)
{
    QTextStream out(stdout);
    out << str;
}

void Helper::printInfo(QString str)
{
    print("\033[90m" + str + "\033[0m");
}

void Helper::printWarning(QString str)
{
    print("\033[93m" + str + "\033[0m");
}

void Helper::printError(QString str)
{
    print("\033[91m" + str + "\033[0m");
}

But the output is like this:

print: Hello World
[90mprintInfo: Hello World
[0m[93mprintWarning: Hello World
[0m[91mprintError: Hello World
[0m

? Offline

Hi! Works for me. What's your operating system?

AliReza Beytari

@Wieland Windows 10.0.10586

? Offline

@AliReza-Beytari Ah, ok. I'm on Linux. Where did you read about the terminal codes? My strong guess would be, that these are codes for a Linux terminal emulator.

AliReza Beytari

@Wieland I had used these ascii codes in one of my Python applications and it worked for windows and linux.

mrjj

@AliReza-Beytari
but dont python comes with its own shell? (or command prompt)

Anyway, you can hax the prompt to support colors
https://web.liferay.com/web/igor.spasic/blog/-/blogs/enable-ansi-colors-in-windows-command-prompt

not tried in win 10. only win 7.
I know its not what u wanted so just considered it a note :)

AliReza Beytari

@mrjj I couldn't use that!! :(

mrjj

@AliReza-Beytari
didnt work on win 10 or what you mean?

AliReza Beytari

@mrjj I just need a very simple code for printing a colored text!! :)

mrjj

@AliReza-Beytari
yes but its not really supported in windows anymore.
In command prompt i mean.
in ooooold times ansi.sys gave us colors. :)

mrjj

update
using native api, there are colors to some degree :)
https://msdn.microsoft.com/en-us/library/windows/desktop/ms682073(v=vs.85).aspx
check out
https://github.com/mattn/ansicolor-w32.c

but your app is then tied to windows :(

AlgorithMan

Yes, the code you have there uses VT100 Escape Codes (note that \033 is the octal representation of character 27=escape. You could also use the hexadecimal \x1b instead), see http://en.wikipedia.org/wiki/ANSI_escape_code

These require a terminal emulator that supports VT100, which almost all linux terminal emulators do. Windows Command Prompt doesn't support them by default, but at the bottom of https://docs.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences there is some code that shows how to turn that on (it's only a few lines of additional code that you only need to run once at the beginning - I would put it into an #ifdef __WIN32 #endif for platform independence.)
I haven't actually tried that though and I'm not sure on which versions of windows it works.

Regarding python: python doesn't natively support VT100 either, but the colorama package https://pypi.org/project/colorama/ enables them (to my knowledge, it replaces the print or write methods with something that extracts the escape codes and does the manipulations via calls to kernel32.dll methods).