cncursesansi-colorsterminfotput

Terminal-agnostic color printing in C without using ncurses


I'm writing a C program that outputs test results, and I'd like it to print them in color so it's easier to scan through the results. I initially just used ANSI color codes (per https://stackoverflow.com/a/23657072/4954731), but a code reviewer wanted it to be more terminal-independent and suggested using ncurses instead.

The problem with using ncurses is that the test results outputted by my C program are interspersed with other test results from bash scripts. Something like this:

Test Name            | Result
------------------------------
1+1 == 2             | PASS     <-- outputted by a C executable
!(!true) == true     | PASS     <-- outputted by a bash script
0+0 == 0             | PASS     <-- outputted by a C executable
...

So I can't use a regular ncurses screen - I have to play nicely with other output.

The bash scripts use tput and setaf to print with color, but I'm not sure if there's a way to use these tools in a C context without directly finding and calling the tput executable...

Is there some way I can do terminal-agnostic color printing in C without using ncurses?


Solution

  • Guess what, tput is actually part of the underlying ncurses C library!

    Here's an example of printing colored text using tput. Don't forget to compile with -lncurses.

    #include <stdio.h>
    #include <curses.h>
    #include <term.h>
    
    int main() 
    {
      // first you need to initialize your terminal
      int result = setupterm(0, 1, 0); 
      if (result != 0) {
        return result;
      }
      printf("%-62.62s  ", "1+1 == 2");
    
      // set color to green. You can pass a different function instead
      // of putchar if you want to, say, set the stderr color
      tputs(tparm(tigetstr("setaf"), COLOR_GREEN), 1, putchar);
    
      // set text to bold
      tputs(tparm(tigetstr("bold")), 1, putchar);
    
      // this text will be printed as green and bold
      printf("PASS\n");
    
      // reset text attributes
      tputs(tparm(tigetstr("sgr0")), 1, putchar);
    
      // now this text won't be green and bold
      printf("Done\n");
    }
    

    As you can see, you can freely mix-and-match tput stuff with regular printf output. There's no need to create a curses screen.

    More information about tputs, tparm, etc here: https://invisible-island.net/ncurses/man/curs_terminfo.3x.html

    Here's a list of what tigetstr capabilities your terminal may have available: https://invisible-island.net/ncurses/man/terminfo.5.html#h3-Predefined-Capabilities