This is a code for find a number whether it's prime or not. Is this code incorrect ???? Thank you. 😊

Question

#include <stdio.h>

void main() {
int a , count = 0;
printf ("enter a number\n");
scanf("%d",&a);

for(int i=1;i<=a;i++) {
if((a%i==0) && (a%1==0))
count++;
}

if((count == 2) || (count == 1))
printf("%d is a prime number\n" , a);

else
printf("%d this is not a prime number\n" , a );

}

Answer 1

Yes it works but try it yourself in the code playground.

Answer 2

You can improve it a little more. Looping upto sqrt(a) is enough, no need to loop upto full a.