C++ Program to Check a Number is Prime Number or not

In this program, the user is ask to enter a number, then that number is determined whether it is Prime or not.

Prime numbers are special numbers, greater than 1, that have exactly two factors, themselves and 1.

19 is a prime number. It can only be divided by 1 and 19.

The prime numbers below 20 are: 2, 3, 5, 7, 11, 13, 17, 19. ...

Source Code

#include <iostream>
using namespace std;

int main()
{
    int no, i, isPrime = 1;
    cout<<"Enter the number : ";
    cin>> no;

    for (i = 2; i <= no/2; i++)
    {
        if (no  % i == 0)
        {
            isPrime = 0;
            break;
        }
    }
    if (isPrime == 1)
    {
        cout<<"Prime number" << no;
    }
    else
    {
        cout<<"Not a Prime number" << no;
    }
    return 0;
}

Output

Enter the number : 17
Prime number

Enter the number : 74
Not a Prime number