Program to Check Whether a Number is Prime or Not

#include<stdio.h>

#include<math.h>

int isPrime(int n)
{
    int root,i;
    //Calculating square root of n
     root=sqrt(n);
    /*  check n against all numbers from 2 to square root of n,
        whether n is divisible by the number */
    for(i=2;i<=root;i++)
    {
    //if divisible, not prime (return zero)
       if(n%i==0)
          return 0;
    }
    return 1;
}

void main()
{
    int input;
    printf("\nEnter the number\n");
    scanf("%d",&input);
    if(isPrime(input))
         printf("\nIt is prime\n");
    else
        printf("\nIt is not prime\n");
}