单例

1.要点在于： 私有的构造函数  静态成员

 

//.h#pragma onceclass single{public:static single* getInstance();~single(void);private:single(void);static single *sinstance;};//,cpp#include "single.h"#include <iostream>using namespace std;single *single::sinstance=new single();;single::single(void){cout<<"Constructed!"<<endl;//sinstance=new single();}single::~single(void){cout<<"destructed"<<endl;} single* single::getInstance() { //if (sinstance==NULL) //{// sinstance=new single(); //} return sinstance; }//.cpp main#include "single.h"#include <iostream>using namespace std;int main(){single *one=single::getInstance();cout<<"end"<<endl;}

 

构造函数访问控制2

 

protected的构造函数，禁止创建该类实例，可以创建派生类实例