C++ 常量成员常量返回值详解

#include "stdafx.h"
#include <iostream>
using namespace std;
class CTest
{
public:
  CTest(int nid, int nlimit):m_cntLimit(nlimit)
  {
    //m_cntLimit = nlimit;// 常量成员必须在构造函数列表在中给出
    m_nId = nid;
  }
  ~CTest(){};

  int GetID() const
  {
    //m_nId++;常量成员函数不能修改对象
    //ClientGetObj();常量成员函数不能调用非常量成员函数
    return m_nId;
  }

  CTest operator =(const CTest &b)
  {
    this->m_nId = b.m_nId;
    //this->m_cntLimit = b.m_cntLimit;// 常量数据成员不能拷贝
    return (*this);
  }

  int ClientGetID()
  {
    return GetID();
  }

  CTest* const GetObj()
  {
    return this;
  }

  CTest* ClientGetObj()
  {
    return this;
  }
  const int GetID()
  {
    return m_nId;
  }

  void Print()
  {
    cout<<"m_nId:"<<m_nId<<", const m_cntLimit"<<m_cntLimit<<endl;
  }

  void PrintCnt() const
  {
    cout<<"m_nId:"<<m_nId<<", const m_cntLimit"<<m_cntLimit<<endl;
  }

private:
  int m_nId;
  const int m_cntLimit;
};
void main()
{
  CTest Obj1(1, 1000);
  CTest Obj2(2, 2000);
  CTest* pObj = Obj1.ClientGetObj();
  pObj->Print();
  CTest objTemp = *(Obj1.ClientGetObj());
  *pObj = *(Obj2.ClientGetObj());
  pObj->Print();
  // reset
  *pObj = objTemp;

  cout<<"-------------const display---------------"<<endl;
   /*const */CTest* const pCntObj = Obj1.GetObj();//常量指针和指针常量都可以赋值给常量指针
  pCntObj->PrintCnt();
  *pCntObj = *(Obj2.GetObj());
  pCntObj->PrintCnt();
  /*const */int nid = pCntObj->GetID();// 常量返回值可以赋值给变量
  nid++;
  cout<<"new nid is:"<<nid<<endl;
  //*pCntObj = *(Obj1.GetObj());// 常量指针对象，不能进行*p操作，可以进行p++操作
  while(1);
}