Question

To Check Whether the Given Number is Prime Number or Not
Write a program to check whether the given number is prime number or not.

Answer 1

#include<stdio.h>
void main()
{
   int a,i;
   clrscr();
   printf("given number:");
   scanf("%d",&a);
     for(i=2;i<a;i++)
      {
         if(a%i==0)
          {
               printf("%d is not prime number",a);
               break;
          }
      }
          if(a==i)
              printf("%d is prime number",a);
     getch();
}
output of the above program is 
given number:13
13 is prime number

Answer 2

Answer:

import java.util.*;

class abc

int main()

{

   int n, i, flag = 0;

   printf("Enter a positive integer: ");

   scanf("%d", &n);

   for (i = 2; i <= n / 2; ++i) {

       // condition for non-prime

       if (n % i == 0) {

           flag = 1;

           break;

       }

   }

   if (n == 1) {

       printf("1 is neither prime nor composite.");

   }

   else {

       if (flag == 0)

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

       else

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

   }

   return 0;

}