Random number remarks

Random number remarks
c Standard library
stdlib.h
srand: Set random number seed
rand: Parameter random number Range 0~32767

c++ Standard library

<random>
default_random_engine

example ：

void testrandom()
{
    
  // In this case, no random seed is set , The values generated during each run are the same 
  std::default_random_engine random;
  std::cout << random() << std::endl;

  // When setting random seeds , Each run does not produce the same value 
  unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
  random.seed(seed);
  std::cout << random() << std::endl;
}

minstd_rand yes minstd_rand0 Improved version Range 1~2147483646
minstd_rand0 Range 1~2147483646
mt19937 Range 0~4294967295 40 More than
mt19937_64 64 position
…
minstd_rand0 minstd_rand default_random_engine All random generators , Generating random numbers .

Generates a random number in a specified range
uniform_int_distribution Can only be int、unsigned、short、unsigned short、long、unsigned long、long long、unsigned long long One of the
uniform_real_distribution The optional type is float、double、long double

Distribution probability
bernoulli_distribution Is a distribution class , But it's not a template class . Its constructor has only one parameter ,
Indicates that this class returns true Probability , This parameter defaults to 0.5 , Return true and false The probability is equal .

The above usage is the following pattern

void testrandom2()
{
    
    // return [0,9]
    unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
    std::default_random_engine random(seed);

    std::uniform_int_distribution<int> distribution(0,9);
    std::cout << distribution(random) << std::endl;
}

More on <random>

boost library ：
Example ：

boost::random::mt19937 rng;         // produces randomness out of thin air
                                    // see pseudo-random number generators
boost::random::uniform_int_distribution<> six(1,6);
                                    // distribution that maps to 1..6
                                    // see random number distributions
int x = six(rng);                   // simulate rolling a die
#include <random>
using namespace std;
int main()
{
    
    //  Random number seed 
	unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
    mt19937 rand_num(seed);	 //  Large random number 
	cout << rand_num() << endl;
	return 0;
}

More on boost::random library