[c++] How do I output coloured text to a Linux terminal?

How do I print coloured characters to a Linux terminal that supports it?

How do I tell whether the terminal supports colour codes?

As others have stated, you can use escape characters. You can use my header in order to make it easier:

#ifndef _COLORS_
#define _COLORS_

/* FOREGROUND */
#define RST  "\x1B[0m"
#define KRED  "\x1B[31m"
#define KGRN  "\x1B[32m"
#define KYEL  "\x1B[33m"
#define KBLU  "\x1B[34m"
#define KMAG  "\x1B[35m"
#define KCYN  "\x1B[36m"
#define KWHT  "\x1B[37m"

#define FRED(x) KRED x RST
#define FGRN(x) KGRN x RST
#define FYEL(x) KYEL x RST
#define FBLU(x) KBLU x RST
#define FMAG(x) KMAG x RST
#define FCYN(x) KCYN x RST
#define FWHT(x) KWHT x RST

#define BOLD(x) "\x1B[1m" x RST
#define UNDL(x) "\x1B[4m" x RST

#endif  /* _COLORS_ */

An example using the macros of the header could be:

#include <iostream>
#include "colors.h"
using namespace std;

int main()
{
    cout << FBLU("I'm blue.") << endl;
    cout << BOLD(FBLU("I'm blue-bold.")) << endl;
    return 0;
}

Basics

I have written a C++ class which can be used to set the foreground and background color of output. This sample program serves as an example of printing This ->word<- is red. and formatting it so that the foreground color of word is red.

#include "colormod.h" // namespace Color
#include <iostream>
using namespace std;
int main() {
    Color::Modifier red(Color::FG_RED);
    Color::Modifier def(Color::FG_DEFAULT);
    cout << "This ->" << red << "word" << def << "<- is red." << endl;
}

Source

#include <ostream>
namespace Color {
    enum Code {
        FG_RED      = 31,
        FG_GREEN    = 32,
        FG_BLUE     = 34,
        FG_DEFAULT  = 39,
        BG_RED      = 41,
        BG_GREEN    = 42,
        BG_BLUE     = 44,
        BG_DEFAULT  = 49
    };
    class Modifier {
        Code code;
    public:
        Modifier(Code pCode) : code(pCode) {}
        friend std::ostream&
        operator<<(std::ostream& os, const Modifier& mod) {
            return os << "\033[" << mod.code << "m";
        }
    };
}

Advanced

You may want to add additional features to the class. It is, for example, possible to add the color magenta and even styles like boldface. To do this, just an another entry to the Code enumeration. This is a good reference.

Before you going to output any color you need make sure you are in a terminal:

[ -t 1 ] && echo 'Yes I am in a terminal'  # isatty(3) call in C

Then you need to check terminal capability if it support color

on systems with terminfo (Linux based) you can obtain quantity of supported colors as

Number_Of_colors_Supported=$(tput colors)

on systems with termcap (BSD based) you can obtain quantity of supported colors as

Number_Of_colors_Supported=$(tput Co)

Then make you decision:

[ ${Number_Of_colors_Supported} -ge 8 ] && {
    echo 'You are fine and can print colors'
} || {
    echo 'Terminal does not support color'
}

BTW, do not use coloring as it was suggested before with ESC characters. Use standard call to terminal capability that will assign you CORRECT colors that particular terminal support.

fg_black="$(tput AF 0)"
fg_red="$(tput AF 1)"
fg_green="$(tput AF 2)"
fg_yellow="$(tput AF 3)"
fg_blue="$(tput AF 4)"
fg_magenta="$(tput AF 5)"
fg_cyan="$(tput AF 6)"
fg_white="$(tput AF 7)"
reset="$(tput me)"

fg_black="$(tput setaf 0)"
fg_red="$(tput setaf 1)"
fg_green="$(tput setaf 2)"
fg_yellow="$(tput setaf 3)"
fg_blue="$(tput setaf 4)"
fg_magenta="$(tput setaf 5)"
fg_cyan="$(tput setaf 6)"
fg_white="$(tput setaf 7)"
reset="$(tput sgr0)"

echo -e "${fg_red}  Red  ${fg_green} Bull ${reset}"

on OSX shell, this works for me (including 2 spaces in front of "red text"):

$ printf "\e[033;31m  red text\n"
$ echo "$(tput setaf 1)  red text"

You can use escape sequences, if your terminal supports it. For example:

echo \[\033[32m\]Hello, \[\033[36m\]colourful \[\033[33mworld!\033[0m\]

I wrote a cross-platform library color_ostream for this, with the support of ANSI color, 256 color and true color, all you have to do is directly including it and changing cout to rd_cout like this.
| std | basic color | 256 color | true color | | :----: | :----: | :----: | :----: | | std::cout | color_ostream::rd_cout | color_ostream::rd256_cout | color_ostream::rdtrue_cout | | std::wcout | color_ostream::rd_wcout | color_ostream::rd256_wcout | color_ostream::rdtrue_wcout | | std::cerr | color_ostream::rd_cerr | color_ostream::rd256_cerr | color_ostream::rdtrue_cerr | | std::wcerr | color_ostream::rd_wcerr | color_ostream::rd256_wcerr | color_ostream::rdtrue_wcerr | | std::clog | color_ostream::rd_clog | color_ostream::rd256_clog | color_ostream::rdtrue_clog | | std::wclog | color_ostream::rd_wclog | color_ostream::rd256_wclog | color_ostream::rdtrue_wclog |
Here is an simple example:

//hello.cpp
#include "color_ostream.h"

using namespace color_ostream;

int main([[maybe_unused]] int argc, [[maybe_unused]] char *argv[]) {
    rd_wcout.imbue(std::locale(std::locale(),"",LC_CTYPE));
    rd_wcout << L"Hello world\n";
    rd_wcout << L"Hola Mundo\n";
    rd_wcout << L"Bonjour le monde\n";

    rd256_wcout << L"\n256 color" << std::endl;
    rd256_wcout << L"Hello world\n";
    rd256_wcout << L"Hola Mundo\n";
    rd256_wcout << L"Bonjour le monde\n";

    rdtrue_wcout << L"\ntrue color" << std::endl;
    rdtrue_wcout << L"Hello world\n";
    rdtrue_wcout << L"Hola Mundo\n";
    rdtrue_wcout << L"Bonjour le monde\n";
    return 0;
}

You can use ANSI colour codes.

use these functions.

enum c_color{BLACK=30,RED=31,GREEN=32,YELLOW=33,BLUE=34,MAGENTA=35,CYAN=36,WHITE=37};
enum c_decoration{NORMAL=0,BOLD=1,FAINT=2,ITALIC=3,UNDERLINE=4,RIVERCED=26,FRAMED=51};
void pr(const string str,c_color color,c_decoration decoration=c_decoration::NORMAL){
  cout<<"\033["<<decoration<<";"<<color<<"m"<<str<<"\033[0m";
}

void prl(const string str,c_color color,c_decoration decoration=c_decoration::NORMAL){
   cout<<"\033["<<decoration<<";"<<color<<"m"<<str<<"\033[0m"<<endl;
}

An expanded version of gon1332's header:

//
//  COLORS.h
//
//  Posted by Gon1332 May 15 2015 on StackOverflow
//  https://stackoverflow.com/questions/2616906/how-do-i-output-coloured-text-to-a-linux-terminal#2616912
//
//  Description: An easy header file to make colored text output to terminal second nature.
//  Modified by Shades Aug. 14 2018

// PLEASE carefully read comments before using this tool, this will save you a lot of bugs that are going to be just about impossible to find.
#ifndef COLORS_h
#define COLORS_h

/* FOREGROUND */
// These codes set the actual text to the specified color
#define RESETTEXT  "\x1B[0m" // Set all colors back to normal.
#define FOREBLK  "\x1B[30m" // Black
#define FORERED  "\x1B[31m" // Red
#define FOREGRN  "\x1B[32m" // Green
#define FOREYEL  "\x1B[33m" // Yellow
#define FOREBLU  "\x1B[34m" // Blue
#define FOREMAG  "\x1B[35m" // Magenta
#define FORECYN  "\x1B[36m" // Cyan
#define FOREWHT  "\x1B[37m" // White

/* BACKGROUND */
// These codes set the background color behind the text.
#define BACKBLK "\x1B[40m"
#define BACKRED "\x1B[41m"
#define BACKGRN "\x1B[42m"
#define BACKYEL "\x1B[43m"
#define BACKBLU "\x1B[44m"
#define BACKMAG "\x1B[45m"
#define BACKCYN "\x1B[46m"
#define BACKWHT "\x1B[47m"

// These will set the text color and then set it back to normal afterwards.
#define BLK(x) FOREBLK x RESETTEXT
#define RED(x) FORERED x RESETTEXT
#define GRN(x) FOREGRN x RESETTEXT
#define YEL(x) FOREYEL x RESETTEXT
#define BLU(x) FOREBLU x RESETTEXT
#define MAG(x) FOREMAG x RESETTEXT
#define CYN(x) FORECYN x RESETTEXT
#define WHT(x) FOREWHT x RESETTEXT

// Example usage: cout << BLU("This text's color is now blue!") << endl;

// These will set the text's background color then reset it back.
#define BackBLK(x) BACKBLK x RESETTEXT
#define BackRED(x) BACKRED x RESETTEXT
#define BackGRN(x) BACKGRN x RESETTEXT
#define BackYEL(x) BACKYEL x RESETTEXT
#define BackBLU(x) BACKBLU x RESETTEXT
#define BackMAG(x) BACKMAG x RESETTEXT
#define BackCYN(x) BACKCYN x RESETTEXT
#define BackWHT(x) BACKWHT x RESETTEXT

// Example usage: cout << BACKRED(FOREBLU("I am blue text on a red background!")) << endl;

// These functions will set the background to the specified color indefinitely.
// NOTE: These do NOT call RESETTEXT afterwards. Thus, they will set the background color indefinitely until the user executes cout << RESETTEXT
// OR if a function is used that calles RESETTEXT i.e. cout << RED("Hello World!") will reset the background color since it calls RESETTEXT.
// To set text COLOR indefinitely, see SetFore functions below.
#define SetBackBLK BACKBLK
#define SetBackRED BACKRED
#define SetBackGRN BACKGRN
#define SetBackYEL BACKYEL
#define SetBackBLU BACKBLU
#define SetBackMAG BACKMAG
#define SetBackCYN BACKCYN
#define SetBackWHT BACKWHT

// Example usage: cout << SetBackRED << "This text's background and all text after it will be red until RESETTEXT is called in some way" << endl;

// These functions will set the text color until RESETTEXT is called. (See above comments)
#define SetForeBLK FOREBLK
#define SetForeRED FORERED
#define SetForeGRN FOREGRN
#define SetForeYEL FOREYEL
#define SetForeBLU FOREBLU
#define SetForeMAG FOREMAG
#define SetForeCYN FORECYN
#define SetForeWHT FOREWHT

// Example usage: cout << SetForeRED << "This text and all text after it will be red until RESETTEXT is called in some way" << endl;

#define BOLD(x) "\x1B[1m" x RESETTEXT // Embolden text then reset it.
#define BRIGHT(x) "\x1B[1m" x RESETTEXT // Brighten text then reset it. (Same as bold but is available for program clarity)
#define UNDL(x) "\x1B[4m" x RESETTEXT // Underline text then reset it.

// Example usage: cout << BOLD(BLU("I am bold blue text!")) << endl;

// These functions will embolden or underline text indefinitely until RESETTEXT is called in some way.

#define SetBOLD "\x1B[1m" // Embolden text indefinitely.
#define SetBRIGHT "\x1B[1m" // Brighten text indefinitely. (Same as bold but is available for program clarity)
#define SetUNDL "\x1B[4m" // Underline text indefinitely.

// Example usage: cout << setBOLD << "I and all text after me will be BOLD/Bright until RESETTEXT is called in some way!" << endl;

#endif /* COLORS_h */

As you can see, it has more capabilities such as the ability to set background color temporarily, indefinitely, and other features. I also believe it is a bit more beginner friendly and easier to remember all of the functions.

#include <iostream>
#include "COLORS.h"

int main() {
  std::cout << SetBackBLU << SetForeRED << endl;
  std::cout << "I am red text on a blue background! :) " << endl;
  return 0;
}

Simply include the header file in your project and you're ready to rock and roll with the colored terminal output.

This is an old topic, but I wrote a class with nested subclasses and static members for colors defined by simple C macros.

I got the color function from this post Color Text In C Programming in dreamincode.net by user no2pencil.

I made it this way so to be able to use the static constants in std::cout stream like this:

cout << zkr::cc::fore::red << "This is red text. " 
     << zkr::cc::console << "And changing to console default colors, fg, bg."
     << endl;

The class and a test program source code can be downloaded here.

cc::console will reset to console default colors and attributes, cc::underline will underline the text, which works on putty which I've tested the test program.

Colors:

black
blue
red
magenta
green
cyan
yellow
white

lightblack
lightblue
lightred
lightmagenta
lightgreen
lightcyan
lightyellow
lightwhite

Which can be used with both fore and back static subclasses of the cc static class.

EDIT 2017

I'm just adding the class code here to be more practical.

The color code macros:

#define CC_CONSOLE_COLOR_DEFAULT "\033[0m"
#define CC_FORECOLOR(C) "\033[" #C "m"
#define CC_BACKCOLOR(C) "\033[" #C "m"
#define CC_ATTR(A) "\033[" #A "m"

and the main color function that defines a color or an attribute to the screen:

char *cc::color(int attr, int fg, int bg)
{
    static char command[13];

    /* Command is the control command to the terminal */
    sprintf(command, "%c[%d;%d;%dm", 0x1B, attr, fg + 30, bg + 40);
    return command;
}

ccolor.h

#include <stdio.h>

#define CC_CONSOLE_COLOR_DEFAULT "\033[0m"
#define CC_FORECOLOR(C) "\033[" #C "m"
#define CC_BACKCOLOR(C) "\033[" #C "m"
#define CC_ATTR(A) "\033[" #A "m"

namespace zkr
{
    class cc
    {
    public:

        class fore
        {
        public:
            static const char *black;
            static const char *blue;
            static const char *red;
            static const char *magenta;
            static const char *green;
            static const char *cyan;
            static const char *yellow;
            static const char *white;
            static const char *console;

            static const char *lightblack;
            static const char *lightblue;
            static const char *lightred;
            static const char *lightmagenta;
            static const char *lightgreen;
            static const char *lightcyan;
            static const char *lightyellow;
            static const char *lightwhite;
        };

        class back
        {
        public:
            static const char *black;
            static const char *blue;
            static const char *red;
            static const char *magenta;
            static const char *green;
            static const char *cyan;
            static const char *yellow;
            static const char *white;
            static const char *console;

            static const char *lightblack;
            static const char *lightblue;
            static const char *lightred;
            static const char *lightmagenta;
            static const char *lightgreen;
            static const char *lightcyan;
            static const char *lightyellow;
            static const char *lightwhite;
        };

        static char *color(int attr, int fg, int bg);
        static const char *console;
        static const char *underline;
        static const char *bold;
    };
}

ccolor.cpp

#include "ccolor.h"

using namespace std;

namespace zkr
{
    enum Color
    {
        Black,
        Red,
        Green,
        Yellow,
        Blue,
        Magenta,
        Cyan,
        White,
        Default = 9
    };

    enum Attributes
    {
        Reset,
        Bright,
        Dim,
        Underline,
        Blink,
        Reverse,
        Hidden
    };

    char *cc::color(int attr, int fg, int bg)
    {
        static char command[13];
        /* Command is the control command to the terminal */
        sprintf(command, "%c[%d;%d;%dm", 0x1B, attr, fg + 30, bg + 40);
        return command;
    }

    const char *cc::console = CC_CONSOLE_COLOR_DEFAULT;
    const char *cc::underline = CC_ATTR(4);
    const char *cc::bold = CC_ATTR(1);

    const char *cc::fore::black = CC_FORECOLOR(30);
    const char *cc::fore::blue = CC_FORECOLOR(34);
    const char *cc::fore::red = CC_FORECOLOR(31);
    const char *cc::fore::magenta = CC_FORECOLOR(35);
    const char *cc::fore::green = CC_FORECOLOR(92);
    const char *cc::fore::cyan = CC_FORECOLOR(36);
    const char *cc::fore::yellow = CC_FORECOLOR(33);
    const char *cc::fore::white = CC_FORECOLOR(37);
    const char *cc::fore::console = CC_FORECOLOR(39);

    const char *cc::fore::lightblack = CC_FORECOLOR(90);
    const char *cc::fore::lightblue = CC_FORECOLOR(94);
    const char *cc::fore::lightred = CC_FORECOLOR(91);
    const char *cc::fore::lightmagenta = CC_FORECOLOR(95);
    const char *cc::fore::lightgreen = CC_FORECOLOR(92);
    const char *cc::fore::lightcyan = CC_FORECOLOR(96);
    const char *cc::fore::lightyellow = CC_FORECOLOR(93);
    const char *cc::fore::lightwhite = CC_FORECOLOR(97);

    const char *cc::back::black = CC_BACKCOLOR(40);
    const char *cc::back::blue = CC_BACKCOLOR(44);
    const char *cc::back::red = CC_BACKCOLOR(41);
    const char *cc::back::magenta = CC_BACKCOLOR(45);
    const char *cc::back::green = CC_BACKCOLOR(42);
    const char *cc::back::cyan = CC_BACKCOLOR(46);
    const char *cc::back::yellow = CC_BACKCOLOR(43);
    const char *cc::back::white = CC_BACKCOLOR(47);
    const char *cc::back::console = CC_BACKCOLOR(49);

    const char *cc::back::lightblack = CC_BACKCOLOR(100);
    const char *cc::back::lightblue = CC_BACKCOLOR(104);
    const char *cc::back::lightred = CC_BACKCOLOR(101);
    const char *cc::back::lightmagenta = CC_BACKCOLOR(105);
    const char *cc::back::lightgreen = CC_BACKCOLOR(102);
    const char *cc::back::lightcyan = CC_BACKCOLOR(106);
    const char *cc::back::lightyellow = CC_BACKCOLOR(103);
    const char *cc::back::lightwhite = CC_BACKCOLOR(107);
}

I use the following solution, it's quite simple and elegant, can be easily pasted into source, and works on Linux/Bash:

const std::string red("\033[0;31m");
const std::string green("\033[1;32m");
const std::string yellow("\033[1;33m");
const std::string cyan("\033[0;36m");
const std::string magenta("\033[0;35m");
const std::string reset("\033[0m");

std::cout << "Measured runtime: " << yellow << timer.count() << reset << std::endl;

The best way is to use the ncurses library - though this might be a sledgehammer to crack a nut if you just want to output a simple coloured string

From my understanding, a typical ANSI color code

"\033[{FORMAT_ATTRIBUTE};{FORGROUND_COLOR};{BACKGROUND_COLOR}m{TEXT}\033[{RESET_FORMATE_ATTRIBUTE}m"

is composed of (name and codec)

• FORMAT ATTRIBUTE

  { "Default", "0" },
  { "Bold", "1" },
  { "Dim", "2" },
  { "Underlined", "3" },
  { "Blink", "5" },
  { "Reverse", "7" },
  { "Hidden", "8" }
  

• FORGROUND COLOR

  { "Default", "39" },
  { "Black", "30" },
  { "Red", "31" },
  { "Green", "32" },
  { "Yellow", "33" },
  { "Blue", "34" },
  { "Magenta", "35" },
  { "Cyan", "36" },
  { "Light Gray", "37" },
  { "Dark Gray", "90" },
  { "Light Red", "91" },
  { "Light Green", "92" },
  { "Light Yellow", "93" },
  { "Light Blue", "94" },
  { "Light Magenta", "95" },
  { "Light Cyan", "96" },
  { "White", "97" }
  

• BACKGROUND COLOR

  { "Default", "49" },
  { "Black", "40" },
  { "Red", "41" },
  { "Green", "42" },
  { "Yellow", "43" },
  { "Blue", "44" },
  { "Megenta", "45" },
  { "Cyan", "46" },
  { "Light Gray", "47" },
  { "Dark Gray", "100" },
  { "Light Red", "101" },
  { "Light Green", "102" },
  { "Light Yellow", "103" },
  { "Light Blue", "104" },
  { "Light Magenta", "105" },
  { "Light Cyan", "106" },
  { "White", "107" }
  

• TEXT

• RESET FORMAT ATTRIBUTE

  { "All", "0" },
  { "Bold", "21" },
  { "Dim", "22" },
  { "Underlined", "24" },
  { "Blink", "25" },
  { "Reverse", "27" },
  { "Hidden", "28" }
  

With this information, it is easy to colorize a string "I am a banana!" with forground color "Yellow" and background color "Green" like this

"\033[0;33;42mI am a Banana!\033[0m"

Or with a C++ library colorize

auto const& colorized_text = color::rize( "I am a banana!", "Yellow", "Green" );
std::cout << colorized_text << std::endl;

More examples with FORMAT ATTRIBUTE here

try my header here for a quick and easy way to color text: Aedi's Color Header

Escape-Sequence-Color-Header

Color Your Output in Unix using C++!!

Text Attribute Options:

ATTRIBUTES_OFF, BOLD, UNDERSCORE, BLINK, REVERSE_VIDEO, CONCEALED

Color Options:

BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE

Format:

General Format, include value you want in $variable$

COLOR_$Foreground_Color$_$Background_Color$
COLOR_$Text_Attribute$_$Foreground_Color$_$Background_Color$
COLOR_NORMAL  // To set color to default

e.g.

COLOR_BLUE_BLACK // Leave Text Attribute Blank if no Text Attribute appied
COLOR_UNDERSCORE_YELLOW_RED
COLOR_NORMAL

Usage:

Just use to stream the color you want before outputting text and use again to set the color to normal after outputting text.

cout << COLOR_BLUE_BLACK << "TEXT" << COLOR_NORMAL << endl;
cout << COLOR_BOLD_YELLOW_CYAN << "TEXT" << COLOR_NORMAL << endl;