Why do I get a implicit declaration of function 'cambiar_color' is invalid in C99 error

Question

So I included in my header

#include <stdio.h>
#include "colores.h"

...

    do{
        tablero[gusano.posFila][gusano.posColumna] = '@';
        for(int i=0; i<FILAS; i++){
            for(int j=0; j<COL; j++){
                if(tablero[i][j] == '#')
                    cambiar_color(WHITE);
                else if(tablero[i][j] == '@')
                    cambiar_color(GREEN);
                else if(tablero[i][j] == '%')
                    cambiar_color(RED);
                printf("%c", tablero[i][j]);
            }
            printf("\n");
        }
        usleep(1000000);
    }while(tablero[gusano.posFila][gusano.posColumna] != '#');
    
    return 0;
}

This part is the only part where i wrote anything related to the colores.h header

I compiled the program using gcc myfile.c colores.c -o myfile but I get this error. (I used cambiar_color(WHITE) as an example in the program

Answer 1

You get an implicit declaration error because cambiar_color() is not declared in your program. Check your header file for the declaration of the function, and if there is no declaration, add one.