C Program to find number of days in a month using switch case

#include <stdio.h>

int main()
{
	int month;
	int days;
	
	printf("Enter month: ");
	scanf("%d",&month);
	
	switch(month)
	{
		case  4:
		case  6:
		case  9:
		case 11:
			days=30;
			break;
		case  1:
		case  3:
		case  5:
		case  7:
		case  8:
		case 10:
		case 12:
			days=31;
			break;
			
		case 2:
			days=28;
			break;
		
		default:
			days=0;
			break;		
	}
	
	if(days)
		printf("Number of days in %d month is: %d\n",month,days);
	else
		printf("You have entered an invalid month!!!\n");
	
	return 0;
	
}