How to Generate Truly Random Numbers in C : Is `rand()` Enough?

How to Generate Truly Random Numbers in C

When developing applications that require the generation of random numbers, such as in dice-rolling games, it's crucial to ensure that the numbers produced are truly random and not biased towards certain values.

The code snippet presented in the question uses the rand() function to generate random numbers within a given range. However, as observed in the output, the same number was generated repeatedly, indicating a lack of randomness.

Issue:

The issue arises from the use of the modulo operator (%) to map the random number to a specific range. While this approach may appear convenient, it can introduce bias depending on the random number generator implementation.

Solution:

To address this issue and generate truly random numbers in C , it's recommended to utilize features introduced in C 11. The following code demonstrates an alternative approach:

#include <random>
#include <iostream>

int main() {
    std::random_device dev;
    std::mt19937 rng(dev());
    std::uniform_int_distribution<std::mt19937::result_type> dist6(1, 6);  // distribution in range [1, 6]

    std::cout << dist6(rng) << std::endl;
}

In this code, the std::random_device class provides a source of entropy to initialize the Mersenne Twister random number generator (std::mt19937). The std::uniform_int_distribution class creates a distribution object within the desired range ([1, 6] in this case).

When calling dist6(rng), a truly random integer within the specified range is generated. By embracing these C 11 features, developers can achieve more randomness and avoid biased results in their applications.

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