prime number in c
#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);
}
}
}