In C++, what is #include <random>?

In C++, #include <random> is a header file that provides facilities for generating random numbers. It offers a powerful and flexible framework for generating various types of random sequences, addressing the limitations of the older rand() function.

Key components of <random>:

1. Engines:

   • Generate sequences of pseudo-random numbers, acting as the base for random number production.
   • Examples:
     • std::mt19937: Mersenne Twister engine (widely used, good quality)
     • std::minstd_rand: Minimal Standard engine (smaller and faster, but lower quality)
     • std::random_device: Non-deterministic engine for seeding other engines (uses hardware sources for randomness)

2. Distributions:

   • Shape the raw output of engines into specific probability distributions.
   • Examples:
     • std::uniform_int_distribution: Generates uniformly distributed integers within a range
     • std::uniform_real_distribution: Generates uniformly distributed real numbers within a range
     • std::normal_distribution: Generates normally distributed real numbers
     • std::bernoulli_distribution: Generates Boolean values (true or false) with a specified probability
     • And more...

Basic usage:

1. Include the header:

   C++

   #include <random>
   

    

2. Create an engine:

   C++

   std::mt19937 engine;  // Mersenne Twister engine
   

    

3. Seed the engine (for non-deterministic results):

   C++

   std::random_device rd;
   engine.seed(rd());
   

    

4. Create a distribution:

   C++

   std::uniform_int_distribution<int> dist(1, 6);  // Generate integers from 1 to 6
   

    

5. Generate random numbers:

   C++

   int random_number = dist(engine);
   

    

Advantages over rand():

• More flexible: Offers a variety of engines and distributions for different needs.
• Better quality: Produces higher-quality random sequences compared to rand().
• Non-deterministic: Can be seeded with non-deterministic sources for true randomness.
• Extensible: Allows for custom engines and distributions.

Remember:

• Use #include <random> instead of rand() for modern C++ random number generation.
• Choose the appropriate engine and distribution based on your specific requirements.
• Seed the engine properly for non-deterministic results.