/*

* prime.c

* This program read and integer number and checks whether it is prime.

*/

#include <stdio.h>

int main ()

{

int n;

int is_prime = 1;

int i;

/* Read the number. */

printf ("Please enter a positive integer: ");

scanf ("%d", &n);

/* Check the input. */

if (n <= 0)

{

printf ("Illegal input!\n");

return (1);

}

/* Check if any of the numbers 2, ... , n-1 divide it. */

for (i = 2; i < n; i++)

{

if (n % i == 0)

{

is_prime = 0;

break;

}

}

/* Print the result. */

if (is_prime)

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

else

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

return (0);

}