mutable.cpp

来自「本课程主要介绍面向对象程序设计的方法和c++语言的基本概念。以c++语言中的面向」· C++ 代码 · 共 33 行

//mutable.cpp
#include <iostream>
#include <string>
using namespace std;
////////////////////////////////////////////////////////////////
class scrollbar
   {
   private:
      int size;                     //related to constness
      mutable string owner;         //not relevent to constness
   public:
      scrollbar(int sz, string own) : size(sz), owner(own) 
         {  }
      void setSize(int sz)             //changes size
         { size = sz; }
      void setOwner(string own) const  //changes owner
         { owner = own; }   
      int getSize() const              //returns size
         { return size; }
      string getOwner() const          //returns owner
         { return owner; }
   };
////////////////////////////////////////////////////////////////
int main()
   {
   const scrollbar sbar(60, "Window1");

// sbar.setSize(100);             //can't do this to const obj
   sbar.setOwner("Window2");      //this is OK
                                  //these are OK too
   cout << sbar.getSize() << ", " << sbar.getOwner() << endl;   
   return 0;
   }