关于拷贝构造函数和等号运算符重载的试验

#include <iostream>
#include <stdlib.h>

using namespace std;

class myclass
      {
          public:
               myclass()
               {
                 cout << "This is myclass()" <<endl;       
                        }; 
               myclass(const myclass &oldone);
          void operator=(const myclass &);    
          private:
               int _a;
               int _b;
               int _c;               
              };
             
int main()
{
    myclass xx;
    myclass yy(xx);
    myclass zz = xx;
    xx = yy;
    system("pause");
    return 0;
    }
 
 myclass::myclass(const myclass &oldone)
 {
      cout << "This is myclass(const myclass &oldone)" <<endl;                 
      _a = oldone._a;
      _b = oldone._b;
      _c = oldone._c;
                          }  
 void myclass::operator=(const myclass &oldone)
 {
      cout << "This is =(const myclass &oldone)" <<endl;                 
      _a = oldone._a;
      _b = oldone._b;
      _c = oldone._c;
      }
   

结果如下图：