C++ Random Number Generator Guide

Random Number Generator Function in C++

This document will guide you through creating a function in C++ that generates N random numbers. We will include all necessary imports, documentation blocks, input validation, and commentary to ensure the code follows best practices.

Necessary Imports

In C++, you typically need to include the following libraries for random number generation and standard I/O operations:

• <iostream> for input and output stream.
• <cstdlib> for the rand() function.
• <ctime> to seed the random number generator with the current time.

Function Definition

#include 
#include 
#include 

/**
 * @brief Generates a list of N random integers.
 * 
 * This function generates N random integers between a specified range.
 * 
 * @param N The number of random integers to generate.
 * @param lower_bound The lower bound of the random number range (inclusive).
 * @param upper_bound The upper bound of the random number range (inclusive).
 * @return std::vector A vector containing N random integers.
 * 
 * @throws std::invalid_argument if N is non-positive or if lower_bound is greater than upper_bound.
 */
std::vector generate_random_numbers(int N, int lower_bound = 0, int upper_bound = 100) {
    // Validate input parameters
    if (N <= 0) {
        throw std::invalid_argument("N must be a positive integer.");
    }
    if (lower_bound > upper_bound) {
        throw std::invalid_argument("lower_bound cannot be greater than upper_bound.");
    }

    // Initialize random seed
    std::srand(std::time(0));

    // Vector to store random numbers
    std::vector random_numbers;
    random_numbers.reserve(N);

    // Generate N random numbers in the provided range
    for (int i = 0; i < N; ++i) {
        int random_num = lower_bound + std::rand() % (upper_bound - lower_bound + 1);
        random_numbers.push_back(random_num);
    }

    return random_numbers;
}

Example Usage

This is a practical example of how the function can be used to generate and display N random numbers.

int main() {
    try {
        int N;
        std::cout << "Enter the number of random numbers to generate: ";
        std::cin >> N;
        
        // Optional: specify the lower and upper bounds for the random numbers
        int lower_bound = 1, upper_bound = 50; 

        std::vector random_numbers = generate_random_numbers(N, lower_bound, upper_bound);

        std::cout << "Generated " << N << " random numbers: ";
        for (int number : random_numbers) {
            std::cout << number << " ";
        }
        std::cout << std::endl;
        
    } catch (const std::invalid_argument &e) {
        std::cerr << "Error: " << e.what() << std::endl;
    }

    return 0;
}

Commentary

1. Input Validation:

   • The function checks if N is a positive integer.
   • Validates that the lower_bound is not greater than the upper_bound.

2. Random Seed Initialization:

   • std::srand(std::time(0)) seeds the random number generator to ensure different outcomes in different executions.

3. Random Number Generation:

   • std::rand() % (upper_bound - lower_bound + 1) generates a random number in the specified range.

By following this approach, you can generate random numbers efficiently and handle potential errors gracefully. For continued learning and more sophisticated use cases, consider exploring more advanced courses and resources available on the Enterprise DNA Platform.