Find the Prime Number in C++ (using "cmath" library)

#include <iostream>

#include <cmath>

bool isPrime(int n) {

    if (n <= 1) return false;

    if (n <= 3) return true;

    if (n % 2 == 0 || n % 3 == 0) return false;

    for (int i = 5; i * i <= n; i += 6) {

        if (n % i == 0 || n % (i + 2) == 0) return false;

    }

    return true;

}

int main() {

    while (true) {

        int n;

        std::cout << "Enter a number (or a negative number to exit): ";

        std::cin >> n;

        if (n < 0) {

            std::cout << "Exiting...\n";

            break;

        }

        if (isPrime(n)) {

            std::cout << n << " is a prime number.\n";

        } else {

            std::cout << n << " is not a prime number.\n";

        }

        std::cout << '\n';

    }

    return 0;

}

Check for Prime Number in C++

This program checks if a given number is prime.

#include <iostream>

int main() {

    int n, i;

    bool isPrime = true;

 

    std::cout << "Enter a positive integer: ";

    std::cin >> n;

 

    if (n == 0 || n == 1) {

        isPrime = false;

    } else {

        for (i = 2; i <= n / 2; ++i) {

            if (n % i == 0) {

                isPrime = false;

                break;

            }

        }

    }

 

    if (isPrime)

        std::cout << n << " is a prime number." << std::endl;

    else

        std::cout << n << " is not a prime number." << std::endl;

 

    return 0;

}

Check for Prime Number in C

This program checks if a given number is prime.

#include <stdio.h>

#include <stdbool.h>

 int main() {

    int n, i;

    bool isPrime = true;

    printf("Enter a positive integer: ");

    scanf("%d", &n);

    if (n == 0 || n == 1) {

        isPrime = false;

    } else {

        for (i = 2; i <= n / 2; ++i) {

            if (n % i == 0) {

                isPrime = false;

                break;

            }

        }

    }

    if (isPrime)

        printf("%d is a prime number.\n", n);

    else

        printf("%d is not a prime number.\n", n);

    return 0;

}

Find the prime number in Python

 import math

def is_prime(n):

    if n <= 1:

        return False

    if n <= 3:

        return True

    if n % 2 == 0 or n % 3 == 0:

        return False

    i = 5

    while i * i <= n:

        if n % i == 0 or n % (i + 2) == 0:

            return False

        i += 6

    return True

def main():

    while True:

        n = int(input("Enter a number (or a negative number to exit): "))

        

        if n < 0:

            print("Exiting...")

            break

        if is_prime(n):

            print(f"{n} is a prime number.")

        else:

            print(f"{n} is not a prime number.")

        print()

if __name__ == "__main__":

    main()