c++基础：37.单例模式

#include <iostream>
class Demo
{public:Demo(const Demo&)=delete;static Demo& Get(){static Demo demo;return demo;}private:Demo(){}
};

写一个生成随机数的单例类

//Random.h
#pragma once
#include <random>
class Random
{
public:Random(const Random&) = delete;static Random& GetInstance();int GetNumber(int min, int max);
private:Random(){}
};

//Random.cpp
#include "Random.h"
Random& Random::GetInstance()
{static Random random;return random;
}
int Random::GetNumber(int min, int max)
{std::random_device rd;std::mt19937 gen(rd());//随机数范围std::uniform_int_distribution<>dis(min, max);return dis(gen);
}

//demo.cpp
#include <iostream>
#include "Random.h"
int main()
{for (int i = 0; i < 10; i++){int num = Random::GetInstance().GetNumber(1, 100);std::cout << num << std::endl;}std::cin.get();
}

这是常规方式，每次使用都需要调用GetInstance（）函数。这里可以使用另一种方法。

//Random.h
#pragma once
#include <random>
class Random
{
public:Random(const Random&) = delete;static Random& GetInstance();//获取随机数static int Number(int min, int max);private:int GetNumber(int min, int max);Random(){}
};

//Random.cpp
#include "Random.h"Random& Random::GetInstance()
{static Random random;return random;
}
int Random::GetNumber(int min, int max)
{std::random_device rd;std::mt19937 gen(rd());//随机数范围std::uniform_int_distribution<>dis(min, max);return dis(gen);
}int Random::Number(int min, int max)
{return GetInstance().GetNumber(min, max);
}

#include <iostream>
#include "Random.h"
int main()
{for (int i = 0; i < 10; i++){std::cout << Random::Number(1,100) << std::endl;}std::cin.get();
}