C++随机数生成器mt19937生成随机数的用法

下面的代码来自官方示例：

// mersenne_twister_engine constructor
#include <iostream>
#include <chrono>
#include <random>
#include <string>

using namespace std;

int main()
{
// obtain a seed from the system clock:
unsigned seed1 = std::chrono::system_clock::now().time_since_epoch().count();

// obtain a seed from the user:
std::string str;
std::cout << "Please, enter a seed: ";
std::getline(std::cin, str);
std::seed_seq seed2(str.begin(), str.end());

std::mt19937 g1(seed1); // mt19937 is a standard mersenne_twister_engine
std::cout << "A time seed produced: " << g1() << std::endl;
std::cout << typeid(g1()).name() << endl;
std::mt19937 g2(seed2);
std::cout << "Your seed produced: " << g2() << std::endl;

return 0;
}