设计模式2---单件模式

//单件设计模式练习
#ifndef _SIGLE_H_
#define _SIGLE_H_
#include <stdio.h>
class Single
{
public :
static Single* Instance()
{
if(m_instance==NULL)//这句是关键，千万不能丢下
{
m_instance=new Single();
}
counter++;
return m_instance;
}
void set(int a)
{
m_data=a;
}
void get()
{
printf("m_data=%d\n",m_data);
}
~Single()
{
printf("xigou\n");
}
void releaseinstance()
{
counter--;
if(counter==0)
{
delete m_instance;
}
}


private:
int m_data;
static int counter;
Single()
{
m_data=0;printf("构造函数\n");
}
static Single* m_instance;

};
int Single::counter=0;

----------------------------------------------------------------------------------cpp-------------------------------------------------------------

#include "stdafx.h"
#include "Single.h"
Single *Single::m_instance=NULL;//静态成员变量初始化，不要忘记
int main(int argc, char* argv[])
{
Single *p1=Single::Instance();
Single *p2=Single::Instance();
p1->set(5);p1->get();
p1->get();
return 0;
}

#endif