That's because you are using string constants "r", "g" and "b" when you want character constants 'r', 'g', and 'b'. Since parameter[0] is a character you can't compare it to a string (character pointer).
That's because you are using string constants "r", "g" and "b" when you want character constants 'r', 'g', and 'b'. Since parameter[0] is a character you can't compare it to a string (character pointer).