Prime Number Generator in C++

Introduction

Prime numbers are numbers greater than 1 that have no divisors other than 1 and themselves. Generating prime numbers is a fundamental concept in computer science and mathematics. This program demonstrates how to generate a list of prime numbers up to a given limit using C++ programming language.

Objective

The objective of this program is to generate a list of prime numbers up to a specified limit input by the user. The program will utilize a straightforward algorithm that checks each number for primality and outputs all prime numbers in the given range.

Prime Number Generator Code in C++

#include 
#include 
using namespace std;

// Function to check whether a number is prime
bool isPrime(int num) {
    if (num <= 1) return false;
    for (int i = 2; i <= sqrt(num); ++i) {
        if (num % i == 0) return false;
    }
    return true;
}

// Function to generate and print prime numbers up to the given limit
void generatePrimes(int limit) {
    cout << "Prime numbers up to " << limit << " are:\n";
    for (int i = 2; i <= limit; ++i) {
        if (isPrime(i)) {
            cout << i << " ";
        }
    }
    cout << endl;
}

int main() {
    int limit;

    // Ask user for the limit
    cout << "Enter the limit up to which you want to generate prime numbers: "; cin >> limit;

    // Generate primes up to the specified limit
    generatePrimes(limit);

    return 0;
}

Explanation of the Program Structure

This C++ program consists of the following key components:

• isPrime Function: This function takes an integer as input and checks whether it is a prime number. It does so by attempting to divide the number by all integers from 2 up to the square root of the number. If any division results in a remainder of zero, the number is not prime.
• generatePrimes Function: This function iterates through numbers from 2 to the user-specified limit and calls the isPrime function for each number. If the number is prime, it is printed.
• main Function: The main function asks the user to enter a limit for prime number generation, then calls the generatePrimes function to display the primes up to that limit.

How to Run the Program

Follow these steps to run the program:

1. Copy the provided code into a new C++ file (e.g., prime_generator.cpp).
2. Open a terminal or command prompt and navigate to the folder where your file is located.
3. Compile the program using a C++ compiler. For example, if you’re using g++, run the command:

   g++ prime_generator.cpp -o prime_generator

4. Run the compiled program:

   ./prime_generator

5. The program will ask you to enter a limit, and it will then display all prime numbers up to that limit.