C extern keyword correct use

I'm writing a simple library to colorize the terminal's text, but maybe i'm doing it wrong.

colors.h:

extern enum col;
extern char* colors[8];
extern char* bold_colors[8];

void printColor(char* color, char* str);

colors.c:

#include <stdio.h>
#include <string.h>
#include <colors.h>

enum col {
    BLACK, RED, GREEN, BLUE, YELLOW, PURPLE, CYAN, WHITE, MAX_VALUE
};

char* colors[8] = {
    [BLACK] = "\033[0;30m",
    [RED] = "\033[0;31m",
    [GREEN] = "\033[0;32m",
    [YELLOW] = "\033[0;33m",
    [BLUE] = "\033[0;34m",
    [PURPLE] = "\033[0;35m",
    [CYAN] = "\033[0;36m",
    [WHITE] = "\033[0;37m"
};

char* bold_colors[8] = {
    [BLACK] = "\033[1;30m",
    [RED] = "\033[1;31m",
    [GREEN] = "\033[1;32m",
    [YELLOW] = "\033[1;33m",
    [BLUE] = "\033[1;34m",
    [PURPLE] = "\033[1;35m",
    [CYAN] = "\033[1;36m",
    [WHITE] = "\033[1;37m"
};

void printColor(char* color, char* str) {
    printf("\033[0;37m");
    printf(color);
    printf(str);
    printf("\033[0;37m");
}

main.c

#include "colors.h"

printColor(colors[GREEN], "text");

The error: identifier "GREEN" is undefinedC/C++(20)

it should share the colors arrays across the files (multiple) but returns an error.

You probably want to move your enum to a header file and include that in both colors.c and main.c

– Allan Wind

I agree with this.

Programming in C includes compilation and linkage.

At compilation stage, declarations in h-files have effect in c-files, but c-files don't affect each other. Your problem happens here. You fix it by placing all used declarations in your h-file.

At linkage stage, compiled c-files are linked together. Your extern declarations take effect here. However, they are needed in the compilation stage too, so it's correct to put them in h-files.