stdlib and colored output in C

Question

I am making a simple application which requires colored output. How can I make my output colored like emacs and bash do?

I don't care about Windows, as my application is only for UNIX systems.

Answer 1

All modern terminal emulators use ANSI escape codes to show colours and other things.
Don't bother with libraries, the code is really simple.

More info is here.

Example in C:

#include <stdio.h>

#define ANSI_COLOR_RED     "\x1b[31m"
#define ANSI_COLOR_GREEN   "\x1b[32m"
#define ANSI_COLOR_YELLOW  "\x1b[33m"
#define ANSI_COLOR_BLUE    "\x1b[34m"
#define ANSI_COLOR_MAGENTA "\x1b[35m"
#define ANSI_COLOR_CYAN    "\x1b[36m"
#define ANSI_COLOR_RESET   "\x1b[0m"

int main (int argc, char const *argv[]) {

  printf(ANSI_COLOR_RED     "This text is RED!"     ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_GREEN   "This text is GREEN!"   ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_YELLOW  "This text is YELLOW!"  ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_BLUE    "This text is BLUE!"    ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_MAGENTA "This text is MAGENTA!" ANSI_COLOR_RESET "\n");
  printf(ANSI_COLOR_CYAN    "This text is CYAN!"    ANSI_COLOR_RESET "\n");

  return 0;
}

Answer 2

Dealing with colour sequences can get messy and different systems might use different Colour Sequence Indicators.

I would suggest you try using ncurses. Other than colour, ncurses can do many other neat things with console UI.

Answer 3

You can assign one color to every functionality to make it more useful.

#define Color_Red "\33[0:31m\\]" // Color Start
#define Color_end "\33[0m\\]" // To flush out prev settings
#define LOG_RED(X) printf("%s %s %s",Color_Red,X,Color_end)

foo()
{
LOG_RED("This is in Red Color");
}

Like wise you can select different color codes and make this more generic.

Answer 4

You can output special color control codes to get colored terminal output, here's a good resource on how to print colors.

For example:

printf("\033[22;34mHello, world!\033[0m");  // shows a blue hello world

EDIT: My original one used prompt color codes, which doesn't work :( This one does (I tested it).

Answer 5

#include <stdio.h>

#define BLUE(string) "\x1b[34m" string "\x1b[0m"
#define RED(string) "\x1b[31m" string "\x1b[0m"

int main(void)
{
    printf("this is " RED("red") "!\n");

    // a somewhat more complex ...
    printf("this is " BLUE("%s") "!\n","blue");

    return 0;
}

reading Wikipedia:

• \x1b[0m resets all attributes
• \x1b[31m sets foreground color to red
• \x1b[44m would set the background to blue.
• both : \x1b[31;44m
• both but inversed : \x1b[31;44;7m
• remember to reset afterwards \x1b[0m ...

Answer 6

If you use same color for whole program , you can define printf() function.

   #include<stdio.h>
   #define ah_red "\e[31m"
   #define printf(X) printf(ah_red "%s",X);
   #int main()
   {
        printf("Bangladesh");
        printf("\n");
        return 0;
   }

Answer 7

Because you can't print a character with string formating. You can also think of adding a format with something like this

#define PRINTC(c,f,s) printf ("\033[%dm" f "\033[0m", 30 + c, s)

f is format as in printf

PRINTC (4, "%s\n", "bar")

will print blue bar

PRINTC (1, "%d", 'a')

will print red 97

Answer 8

Expanding on the answer of @AndrejsCainikovs, here is a code that works for 24-bits rgb code (both for font and background color) with terminals that supports such code (Xterm, KDE's Konsole, and iTerm, as well as all libvte based terminals, including GNOME Terminal according to https://en.wikipedia.org/wiki/ANSI_escape_code#Colors):

#include <stdio.h>

#define ANSI_FONT_COL_RESET     "\x1b[0m"
#define FONT_COL_CUSTOM_RED     "\e[38;2;200;0;0m" // where rrr;ggg;bbb in 38;2;rrr;ggg;bbbm can go from 0 to 255 respectively
#define FONT_COL_CUSTOM_GREEN   "\e[38;2;0;200;0m" // where rrr;ggg;bbb in 38;2;rrr;ggg;bbbm can go from 0 to 255 respectively
#define FONT_COL_CUSTOM_BLUE    "\e[38;2;0;0;200m" // where rrr;ggg;bbb in 38;2;rrr;ggg;bbbm can go from 0 to 255 respectively
#define BCKGRD_COL_CUSTOM_RED   "\e[48;2;200;0;0m" // where rrr;ggg;bbb in 48;2;rrr;ggg;bbbm can go from 0 to 255 respectively
#define BCKGRD_COL_CUSTOM_GREEN "\e[48;2;0;200;0m" // where rrr;ggg;bbb in 48;2;rrr;ggg;bbbm can go from 0 to 255 respectively
#define BCKGRD_COL_CUSTOM_BLUE  "\e[48;2;0;0;200m" // where rrr;ggg;bbb in 48;2;rrr;ggg;bbbm can go from 0 to 255 respectively

int main (int argc, char const *argv[]) {

  printf(FONT_COL_CUSTOM_RED     "This font color is CUSTOM_RED!"           ANSI_FONT_COL_RESET "\n");
  printf(FONT_COL_CUSTOM_GREEN   "This font color is CUSTOM_GREEN!"         ANSI_FONT_COL_RESET "\n");
  printf(FONT_COL_CUSTOM_BLUE    "This font color is CUSTOM_BLUE!"          ANSI_FONT_COL_RESET "\n");
  printf(BCKGRD_COL_CUSTOM_RED   "This background color is CUSTOM_RED!"     ANSI_FONT_COL_RESET "\n");
  printf(BCKGRD_COL_CUSTOM_GREEN "This background color is CUSTOM_GREEN!"   ANSI_FONT_COL_RESET "\n");
  printf(BCKGRD_COL_CUSTOM_BLUE  "This background color is CUSTOM_BLUE!"    ANSI_FONT_COL_RESET "\n");
  printf(FONT_COL_CUSTOM_GREEN BCKGRD_COL_CUSTOM_RED "This font color is CUSTOM_GREEN with background CUSTOM_RED!"    ANSI_FONT_COL_RESET "\n");
  printf(                        "This font color is NORMAL!\n");

  return 0;
}