Answer to Question #345235 in C++ for Ali

Question

Input a positive integer from the user and determine whether the number is a prime number or not.

Answer 1

#include <iostream>


int main()
{
	int num;
	std::cout << "Enter a positive integer: ";
	std::cin >> num;
	
	bool is_prime = true;
	if (num < 2)
	{
		is_prime = false; // 0 and 1 are not prime
	}
	else
	{
		for (int i = 2; i <= num / 2; ++i)
		{
			if (num % i == 0)
			{
				is_prime = false;
				break;
			}
		}
	}

	if (is_prime)
		std::cout << num << " is a prime number";
	else
		std::cout << num << " is not a prime number";

	return 0;
}