C++单例

#include<iostream>
using namespace std;

class CPeople
{
 private:
  static int flag;//判断是否定义了对象
 private:
  CPeople()//构造函数为私有
 {

 }
 ~CPeople()//析构函数为私有
 {
  CPeople::flag=0;//变量改变
 }
 public :
  static CPeople *GetObject()//获取一个对象
 {
  if(CPeople::flag==0)//判断是否可以获取
  {
   CPeople::flag=1;//变量改变
   return new CPeople;//返回对象
  }
  return NULL;//已定义返回NULL
 }
 static void DeleteObject(CPeople *&pObject)//删除对象
 {
  delete pObject;
  pObject=NULL;
 }

 void Show()//检测是否定义了对象
 {
  cout<<"CPeople::Show()"<<endl;
 }
};
int CPeople::flag=0;//静态成员在类外初始化
int main()
{
 CPeople *p=CPeople::GetObject();
 if(p!=NULL)
 {
  p->Show();
 }
 else
 {
  cout<<"NULL"<<endl;
 }
 CPeople::DeleteObject(p);
 p=CPeople::GetObject();
 if(p!=NULL)
 {
  p->Show();
 }
 else
 {
  cout<<"NULL"<<endl;
 }
 //CPeople kk(*p);//不能调用析构函数进行析构
 return 0;
}