C Program to check if a number is prime number or not

Program

#include<stdio.h>
void main()
{
	int i, flag, n;
	flag = 0;
	printf("Enter the number:\t");
	scanf("%d", &n);
	for(i = 2; i <= n/2; i++)
	{
		if(n % i == 0)
		{
			flag = 1;
			break;
		}
	}
	if(flag == 0)
		printf("%d is a prime number\n", n);
	else
		printf("%d is not a prime number\n", n);
}

Output 1

Enter the number:	56
56 is not a prime number

Output 2

Enter the number:	17
17 is a prime number