Colored output in C++

Question

Is there a way to print colored output using iostream and Xcode? I\'d like to be able to, for example, print Hello World! with Hello red,

Answer 1

Use {fmt} library, which is being slowly absorbed into C++ standard, starting with C++20 in header. Text colors and styles are not in the standard yet, AFAIK, but you can get them with the version on github, where you can find this example:

#include <fmt/color.h>

int main() {
  fmt::print(fg(fmt::color::crimson) | fmt::emphasis::bold,
             "Hello, {}!\n", "world");
  fmt::print(fg(fmt::color::floral_white) | bg(fmt::color::slate_gray) |
             fmt::emphasis::underline, "Hello, {}!\n", "мир");
  fmt::print(fg(fmt::color::steel_blue) | fmt::emphasis::italic,
             "Hello, {}!\n", "世界");
}

Answer 2

You need the terminal color codes. For linux it's the following (your system might be different, look it up):

//the following are UBUNTU/LINUX, and MacOS ONLY terminal color codes.
#define RESET   "\033[0m"
#define BLACK   "\033[30m"      /* Black */
#define RED     "\033[31m"      /* Red */
#define GREEN   "\033[32m"      /* Green */
#define YELLOW  "\033[33m"      /* Yellow */
#define BLUE    "\033[34m"      /* Blue */
#define MAGENTA "\033[35m"      /* Magenta */
#define CYAN    "\033[36m"      /* Cyan */
#define WHITE   "\033[37m"      /* White */
#define BOLDBLACK   "\033[1m\033[30m"      /* Bold Black */
#define BOLDRED     "\033[1m\033[31m"      /* Bold Red */
#define BOLDGREEN   "\033[1m\033[32m"      /* Bold Green */
#define BOLDYELLOW  "\033[1m\033[33m"      /* Bold Yellow */
#define BOLDBLUE    "\033[1m\033[34m"      /* Bold Blue */
#define BOLDMAGENTA "\033[1m\033[35m"      /* Bold Magenta */
#define BOLDCYAN    "\033[1m\033[36m"      /* Bold Cyan */
#define BOLDWHITE   "\033[1m\033[37m"      /* Bold White */

This allows you to do the following:

std::cout << RED << "hello world" << RESET << std::endl;

Note: If you don't use RESET the color will remain changed until the next time you use a color code.

Answer 3

In a more c++ way for an ANSI capable terminal, it is possible to write your own ansi stream manipulators like std::endl but for handling ansi escape code.

Code for doing so can look like this for basic raw implementation:

namespace ansi {
  template < class CharT, class Traits >
  constexpr
  std::basic_ostream< CharT, Traits > & reset( std::basic_ostream< CharT, Traits > &os )
  {
     return os << "\033[0m";
  }

  template < class CharT, class Traits >
  constexpr
  std::basic_ostream< CharT, Traits > & foreground_black( std::basic_ostream< CharT, Traits > &os )
  {
     return os << "\033[30m";
  }

  template < class CharT, class Traits >
  constexpr
  std::basic_ostream< CharT, Traits > & foreground_red( std::basic_ostream< CharT, Traits > &os )
  {
     return os << "\033[31m";
  }
  ...
 } // ansi

And it can be used in a code like this:

std::cout << ansi::foreground_red << "in red" << ansi::reset << std::endl;