Circular Prime

 /* C code to check whether a number obtained by circularly shifting its digits is prime or not*/
#include <stdio.h>
//function for finding the number of digits in a given number
int get_num_digits(n)
{
    int k = 0;
    while (n!=0)
    {
        n = n/10;
        k++;
    }
    return k;
}

//function for finding a circular number
int get_shifted_num(n)
{

    int i , d, k = 1 , last_digit , new_num;

    d= get_num_digits(n);

    for (i=1 ; i<=(d-1); i++)
        k = k*10;

    last_digit = n/k;

    new_num = (n - last_digit*k)*10 + last_digit;
    return new_num;
}

//function to check whether a number is prime or not
 is_prime(n)
{
    int  i , circular_num =n;   
    for (i=1; i<=circular_num/2 ; i++)
        if (circular_num%(i+1) == 0)
                return  0 ;
    return 1;           
}

int main ()
{
    int i , n , d ,  circular_num , z;

    printf("enter a number : ");
    scanf("%d", &n);

    d = get_num_digits(n);
   
    circular_num =n;

    for (i = 1; i<=d ; i++)
    {
        printf ("shifted no. is  : %d\n", circular_num);
        z = is_prime(circular_num);

        if (z==1)
            printf ("%d is prime\n\n", circular_num);
        else
            printf ("%d is not prime: \n\n" , circular_num);

        circular_num = get_shifted_num(circular_num);
    }
    return 0;
}