#include<stdio.h>
void main()
{
    int num;
    int prime = 1;
    printf("Enter a number = ");
    scanf("%d",&num);


    for(int i = 2; i < num; i++)
    {
        if(num % i == 0)
        {
            prime = 0;
            break;
        }
    }
    if(prime == 1 && num>0 && num !=1)
    {
        printf("%d is a prime number.", num);
    }
    else
    {
        printf("%d isn't a prime number.", num);
    }
}

#include<stdio.h>
void main(){
    int num, i;
    int cp = 1;
    printf("Enter a number = ");
    scanf("%d",&num);

    if(num > 0){
        for(i = 2; i < num; i++){
            if(num % i == 0){
                cp = 0;
            }
        }
        if(cp == 1){
            printf("%d is a prime number.", num);
        }
        else{
            printf("%d isn't a prime number.", num);
        }
    }
}

int isPrime(int n) {
  for (int i = 2; i < n; i++) if (n % i == 0) return 0; 
  return 1;
}