This is just a quick video that I am doing to show that you can have negative numbers in a switch/case statement, inside of a C program. The only requirement that I know of is that you must be using GCC to compile (which sensible person doesn't), because the GNU programmers obviously realised that they can't be in a position where their compiler is saying that they are not allowed to do something that is very useful. If GCC did not support this feature, then I would have to resort to typing a whole lot more unnecessary code.

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
	int x = atoi(argv[1]);
        switch(x) {
		case -80 ... -51:
			printf("Number is in between -80 to -51\n");
			break;			
		case -50 ... 32:
			printf("Number is in between -50 to 32\n");
			break;			
		case 33 ... 66:
			printf("Number is in between 33 to 66\n");
			break;			
		case 67 ... 100:
			printf("Number is in between 67 to 100\n");
			break;			
		//default case
		default:
			printf("Number is out of range!!!\n");
			break;							
	}
}</stdlib.h></stdio.h>