Program to check whether the number is prime or not

0 Suresh Chand March 28, 2021

In this article, We will check whether number is prime is not.

Prime Numbers are those numbers which is divisible by 1 and itself. Eg: 2,3,5,7,11 etc.

We will check the prime number by simply dividing all the number below that number. Suppose, If we have to check the 5 then we will divide 5 by 2,3 and 4. If the anyone gives remainder 0 then that is not a prime.

Let’s look and example to make clear concepts

using namespace std;

int main()
    int num, i, flag = 0;

    cout << "Enter a Number: ";
    cin >> num;

    for( i = 2; i < num; i++)
        if( num % i == 0)
            flag = 1;
    if( flag == 0 )
        cout << "\nIt is a Prime Number" << endl;
        cout << "\nIt is not a Prime Number" << endl;
    return 0;

The output of above program is

Enter a number : 5
It is a Prime Number

Enter a number : 6
It is not a Prime Number

Let’s understand how program working:

  • Step 1: First we will initialize variables num, i and flag = 1
  • Step 2: We will read the number
  • Step 3: We will loop from 2 to that number. If any number gives remainder while dividing then we will set flag = 1
  • Step 4: After loop end, We will change whether flag value is o or 1. If flag value has initial value then number is prime else number is not prime.
Notify of
Inline Feedbacks
View all comments

Join Our Newsletter Now

Get the latest tutorials, examples and projects updates.



Ads Blocker Detected!!!

We have detected that you are using extensions to block ads. Please support us by disabling these ads blocker.

Disable Ad Block

Want Same System