Cpp program to check whether it is a prime number or not using for loop

Write a cpp code to input a number and check whether it is a prime number or not.

#include<iostream>
using namespace std;
int main(){
     int num,a;
     bool isPrime = true;
     cout<<"Enter any positive integer number";
     cin>>num;
	if(num==1){
	cout<	}
     for(a=2;a<=num/2;a++){
        if(num%a==0)
        {
            isPrime=false;
            break;
        }
     }
     if (isPrime) {
        cout << num << " is a prime number" << endl;
    } else {
       cout << num << " is not a prime number" << endl;
    }
     return 0; 
}

Output:

Enter any positive integer number 12

12 is not a prime number