# <random>

**[<random>](https://en.cppreference.com/w/cpp/header/random)** provides random number engines (`std::mt19937`, `std::random_device`) and distributions (`std::uniform_int_distribution`, `std::normal_distribution`). Engine and distribution are separate to allow reusing an engine with different distributions.

Always seed with a good entropy source: `std::random_device()` for unpredictable values, or a fixed seed for reproducibility.

## Example

This example generates a random die roll and a normally-distributed random value using different distributions with the same engine.

```cpp
// compile: g++ -std=c++11 -o randomexample randomexample.cpp
// run: ./randomexample
// description: random integers and normal distribution

#include <random>
#include <iostream>

int main() {
    std::mt19937 gen(std::random_device{}());
    std::uniform_int_distribution<int> dist(1, 6);
    
    std::cout << "die roll: " << dist(gen) << "\n";
    
    std::normal_distribution<double> normal(0.0, 1.0);
    std::cout << "normal: " << normal(gen) << "\n";
    
    return 0;
}
```