C++ Program to Check Whether a Number is Prime or Not

In this tutorial you will learn about the C++ Program to Check Whether a Number is Prime or Not and its application with practical example.

In this tutorial, we will learn to create a C++ program that will Check Whether a Number is Prime or Not using C++ programming.

Table Of Contents−

Prerequisites

Before starting with this tutorial we assume that you are best aware of the following C++ programming topics:

Operators in C++ Programming.

Basic Input and Output function in C++ Programming.
Basic C++ programming.
For loop in C++ programming.

Conditional Statements in C++ programming.
Arithmetic operations in C++ Programming.

Program to Check Whether a Number is Prime or Not:-

In c++ programming, it is possible to take numerical input from the user and check if that number is Prime Number or not. The prime number means a number that is only divisible by itself.

With the help of this program, we can Check Whether a Number is Prime or Not.

Algorithm:-

1. Declaring the variables for the program.

2. Taking the input number from the user.

3. Calculating the number is a prime number or not.

4. Printing the result.

5. End the program.

1. Declaring the variables for the program.

2. Taking the input number from the user.

3. Calculating the number is a prime number or not.

4. Printing the result.

5. End the program.

Program to Check Whether a Number is Prime or Not:-

#include <iostream>
using namespace std;

bool checkPrimeNumber(int);

int main() 
{
    //declaring the variables for the program
    int n;
  
    //taking the input from the user 
    cout << "Enter a positive  integer: ";
    cin >> n;
   
    //Printing the number is prime or not 
    if (checkPrimeNumber(n))
        cout << n << " is a prime number.";
    else
        cout << n << " is not a prime number.";
    return 0;
}

bool checkPrimeNumber(int n) 
{
    //checking the [prime number]
    bool isPrime = true;

    // 0 and 1 are not prime numbers
    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;
}

#include <iostream>

using namespace std;

bool checkPrimeNumber(int);

int main()

{

//declaring the variables for the program

int n;

//taking the input from the user

cout << "Enter a positive integer: ";

cin >> n;

//Printing the number is prime or not

if (checkPrimeNumber(n))

cout << n << " is a prime number.";

else

cout << n << " is not a prime number.";

return 0;

}

bool checkPrimeNumber(int n)

{

//checking the [prime number]

bool isPrime = true;

// 0 and 1 are not prime numbers

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;

}

Output:-

In the above program, we have first initialized the required variable.

no= it will hold the integer value of the input.

i = it will hold the integer value.
flag = it will hold the integer value.

Input message for the user for the integer value.

Program Logic Code.

Printing output prime number or not.

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C++ Program to Check Whether a Number is Prime or Not