Write a program to find a prime number between 2 numbers using call function

Question

#include <iostream>
using namespace std;

bool isPrime(int num){
for(int i=2;i<=num;i++){
if(num%i==0){
return false;
}
}
return true;
}

int main() {
int a,b;
cin>>a>>b;
for(int i=a;i<=b;i++){
if(isPrime(i)){
cout<<i<<endl;
}
}
return 0;
}

Answer 1

In you isPrime() function, you are iterating till the number itself, and (num%num) will always equate to zero.

Simple fix
Change "<= num" to "< num" to get desired output
https://code.sololearn.com/c3bonIZTGz87/?ref=app

optimised fix:
you don't even have to iterate till num-1 to check if the number is prime or not, you can also check untill (num/2) or better (sqrt(num))

Answer 2

Yeah it's working thanks 😁