índice.c

int indiceDeCaracterEnCadena(char *cadena, char caracter)
{
    int indice = 0;
    while (cadena[indice] != '\0')
    {
        char actual = cadena[indice];
        if (actual == caracter)
        {
            return indice;
        }
        indice++;
    }
    return -1;
}