How can I generate truly uniform random numbers within a specific range in C ?

Generate Random Numbers Uniformly Over an Entire Range

To generate random numbers within a specified interval [min, max] uniformly, the following guidelines should be considered:

Avoid Using rand() and Modulo Operator

Using rand() and the modulo operator, as demonstrated in the given code snippet, may not produce uniformly distributed random numbers. It depends on the range and the value of RAND_MAX.

C 11 Uniform Integer Distribution

With C 11, you can utilize std::uniform_int_distribution to generate random numbers within a range:

#include <iostream>
#include <random>

int main() {
    const int range_from = 0;
    const int range_to = 1000;
    std::random_device rand_dev;
    std::mt19937 generator(rand_dev());
    std::uniform_int_distribution<int> distr(range_from, range_to);

    std::cout << distr(generator) << '\n';
}

Other Random Number Generators

C 11 provides additional random number generators with various distributions, such as Bernoulli, Poisson, and normal.

Shuffling Containers

To shuffle a container randomly, use std::shuffle:

#include <iostream>
#include <random>
#include <vector>

int main() {
    std::vector<int> vec = {4, 8, 15, 16, 23, 42};

    std::random_device random_dev;
    std::mt19937 generator(random_dev());

    std::shuffle(vec.begin(), vec.end(), generator);
    std::for_each(vec.begin(), vec.end(), [](auto i){std::cout << i << '\n';});
}

Boost.Random

If C 11 is not available, you can use Boost.Random, which offers an interface similar to C 11's random number generation facilities.

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