C++学习随笔——简单的单例设计模式实例

#include <iostream>

class Singleton {
private:
    // 私有化构造函数，防止外部实例化
    Singleton() {
        std::cout << "Singleton Instance Created!" << std::endl;
    }

    // 删除拷贝构造函数和赋值运算符，防止拷贝实例
    Singleton(const Singleton&) = delete;
    Singleton& operator=(const Singleton&) = delete;

public:
    // 提供一个全局访问点，返回唯一实例
    static Singleton& getInstance() {
        static Singleton instance;  // 静态局部变量，第一次调用时创建实例
        return instance;
    }

    void showMessage() {
        std::cout << "Hello from Singleton!" << std::endl;
    }
};

int main() {
    // 获取Singleton的唯一实例并调用方法
    Singleton& singleton1 = Singleton::getInstance();
    singleton1.showMessage();

    // 再次获取实例
    Singleton& singleton2 = Singleton::getInstance();

    // 检查两个实例是否相同
    if (&singleton1 == &singleton2) {
        std::cout << "singleton1 and singleton2 are the same instance." << std::endl;
    } else {
        std::cout << "singleton1 and singleton2 are different instances." << std::endl;
    }

    return 0;
}