C++11随机数_c++ rd()-优快云博客

本文链接：https://blog.youkuaiyun.com/kinly_jiang/article/details/50469658

本文介绍了一个使用C++11标准库实现的随机数生成器类。该类利用了std::default_random_engine, std::mt19937_64以及std::random_device等组件，并提供了通用的接口来生成指定范围内的随机整数和浮点数。

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#pragma once

#include <random>

// C++11随机数
class random_help
{
private:
	std::default_random_engine _engine;
	std::mt19937_64 _mt19937_gen;
	std::random_device _rd;
private:
	// noncopyable
	random_help(random_help&&)=delete;
	random_help& operator=(random_help&&)=delete;
	random_help(random_help const&)=delete;
	random_help& operator=(random_help const&)=delete;
public:
	random_help()
		:_mt19937_gen(_rd())
	{}
	~random_help()
	{}
	template<class _Ty1, class _Ty2, typename std::enable_if<std::is_integral<_Ty1>::value && std::enable_if<std::is_integral<_Ty1>::value, bool>::type = true>
	auto operator()(_Ty1 min_, _Ty2 max_)->decltype(min_ + max_)
	{
		if (min_ == max_)
			return min_;
		using _Ty = decltype(min_ + max_);
		_Ty _min = static_cast<_Ty>(min_);
		_Ty _max = static_cast<_Ty>(max_);

		if (_min > _max)
		{
			std::swap(_min, _max);
		}
		return std::uniform_int_distribution<_Ty>(_min, _max)(_mt19937_gen);
	}
	template<class _Ty1, class _Ty2, typename std::enable_if<std::is_floating_point<_Ty1>::value && std::enable_if<std::is_floating_point<_Ty1>::value, bool>::type = true>
	auto operator()(_Ty1 min_, _Ty2 max_)->decltype(min_ + max_)
	{
		if (min_ == max_)
			return min_;
		using _Ty = decltype(min_ + max_);
		_Ty _min = static_cast<_Ty>(min_);
		_Ty _max = static_cast<_Ty>(max_);

		if (_min > _max)
		{
			std::swap(_min, _max);
		}
		// uniform_real_distribution 是 [ )，用std::nextafter修正使取到[ ]
		if (std::is_same<float, _Ty>::value || std::is_same<unsigned float, _Ty>::value)
			return std::uniform_real_distribution<_Ty>(_min, std::nextafter(_max, FLT_MAX))(_mt19937_gen);
		else if (std::is_same<double, _Ty>::value || std::is_same<unsigned double, _Ty>::value)
			return std::uniform_real_distribution<_Ty>(_min, std::nextafter(_max, DBL_MAX))(_mt19937_gen);
		else // if (std::is_same<long double, _Ty>::value || std::is_same<unsigned long double, _Ty>::value)
			return std::uniform_real_distribution<_Ty>(_min, std::nextafter(_max, LDBL_MAX))(_mt19937_gen);
	}
};