if (colour == 'r') {
   printf("Red");
} else if (colour == 'g') {
   printf("Green");
} else if (colour == 'b') {
   printf("Blue");
}
else {
   printf("Invalid Colour");
}

switch (colour) {
case 'r':
   printf("Red"); break;
case 'g':
   printf("Green"); break;
case 'b':
   printf("Blue"); break;
default:
   printf("Invalid Colour");
}