Оператор goto case

//C has no goto case: without break
//the execution falls through into the next case,
//and C23 [[fallthrough]] marks it as intended
int firstNumber = 1;
char numbers[16] = "";
switch (firstNumber) {
    case 1:
        strcat(numbers, "1");
        [[fallthrough]];
    case 2:
        strcat(numbers, "-2");
        [[fallthrough]];
    case 3:
        strcat(numbers, "-3");
        break;
}
//numbers is "1-2-3"

printf("numbers is %s\n", numbers);