Program to check prime number using Functions

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

To understand this example, You must have knowledge in following topics

• For Loop
• Functions

Lets look a code

#include <iostream>
using namespace std;

bool isPrimeNumber(int);

int main() {
    int n;

    cout << "Enter a positive  integer: ";
    cin >> n;

    if (isPrimeNumber(n))
        cout << n << " is a prime number.";
    else
        cout << n << " is not a prime number.";
    return 0;
}

bool isPrimeNumber(int n) {
    bool isPrime = true;

    // Since, 0 and 1 are not prime
    if (n == 0 || n == 1) {
        isPrime = false;
    }
    else {
        for (int i = 2; i <= n / 2; ++i) {
            if (n % i == 0) {
                isPrime = false;
                break;
            }
        }
    }
    return isPrime;
}

The output of above code is

Enter a positive  integer: 12
12 is not a prime number.

Enter a positive  integer: 5
5 is a prime number.

In this example, We have create one function isPrimeNumber() which return Boolean value.

It accepts one number and return Boolean(true or false) value. It return true if number passed is prime number and false it number passed is not prime number.

To know the detail about the program to check prime number.

• Program to check whether the number is prime or not

Please check that example for detail explanation to check the prime number using C++ programming language.