54 lines
1.0 KiB
C++
54 lines
1.0 KiB
C++
// 类的单例设计模式
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// 私有化构造函数和拷贝函数， 提供一个public的静态函数返回类的指针对象， 声明一个静态的类
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// 的指针对象。
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#include <iostream>
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#include <cstring>
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#include <cstdlib>
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using namespace std;
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class A // 单例的类: 类的对象运行期间有且只有一个对象
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{
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private:
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int x;
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A(int x) { this->x = x; }
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A(const A &other)
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{
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x = other.x;
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}
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public:
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static A *getInstance(int x = 0)
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{
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if (instance == NULL)
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{
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instance = new A(x);
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}
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return instance;
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}
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void show()
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{
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cout << "x = " << x << endl;
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}
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public:
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static A *instance;
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};
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A *A::instance = NULL; // 定义初始化，在静态全局区
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int main()
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{
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A *a1 = A::getInstance(20);
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a1->show();
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A *a2 = A::getInstance();
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a2->show();
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cout << "a1 addr = " << a1 << endl;
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cout << "a2 addr = " << a2 << endl;
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delete A::instance; // 释放单例对象的空间
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return 0;
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}
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