Command Line Program to Check if a Number is Prime or Not

It is highly advisable to go through Command Line Arguments Post before even looking at the code. Please study this for TCS and come back to this post later

#include <stdio.h>

int main(int argc, char *argv[])

{

             int n, i, flag = 0;

             n = atol(argv[1]);

            for(i=2; i<=n/2; ++i)

   {

            if(n%i==0)

      {

            flag=1;

            break;

      }

   }

   if (flag==0)

            printf("%d is a prime number.",n);

   else

            printf("%d is not a prime number.",n);

   return 0;

}

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