ANSI Color Codes

Question

When I ran this command on linux $ gcc, it gave me an output like this:

gcc: fatal error: no input files
compilation terminated.

Where, gcc was in bold white color and fatal error: was in bold red color.

And then I ran this command $ gcc &> err.txt and the content of err.txt was:

gcc: fatal error: no input files
compilation terminated.

With no ANSI color codes, just the plain text.

But with my program written in C++, the text file's content was:

[1;91merr:[0m no arguments were passed, try using '--help'

Where err: was in bold red color with showed up in terminal but the file too contains those characters.

My sample code is:

if (argc == 1)
{
    std::fprintf(stderr, "\033[1;91merr:\033[0m no arguments were passed, try using '--help'\n");
    return EXIT_FAILURE;
}

My Question:

1. How does gcc and other linux programs prints colored text on terminal without using ANSI color codes?
2. Are there any other methods to print colored output on terminal except ANSI color codes?
3. Are there any cross-platform libraries todo so?