C Program to Find whether a Number is Prime or Not using Recursion

#include < stdio.h>
 
int primeno(int, int);
 
int main()
{
    int num, check;
    printf("Enter a number: ");
    scanf("%d", &num);
    check = primeno(num, num / 2);
    if (check == 1)
    {
        printf("%d is a prime number\n", num);
    }
    else
    {
        printf("%d is not a prime number\n", num);
    }
    return 0;
}
 
int primeno(int num, int i)
{
    if (i == 1)
    {
        return 1;
    }
    else
    {
       if (num % i == 0)
       {
         return 0;
       }
       else
       {
         return primeno(num, i - 1);
       }       
    }
}

Output

 Enter a number:  456 
 456  is not a prime number
 
   
Enter a number:  89 
 89  is a prime number

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