fig06_23.cpp

来自「《c＋＋大学教程》源码」· C++ 代码 · 共 54 行

// Fig. 6.23: fig06_23.cpp
// Demonstrating a public member function that
// returns a reference to a private data member.
#include <iostream>

using std::cout;
using std::endl;

// include definition of class Time from time4.h
#include "time4.h"

int main()
{
   Time t;

   // store in hourRef the reference returned by badSetHour
   int &hourRef = t.badSetHour( 20 );

   cout << "Hour before modification: " << hourRef;

   // use hourRef to set invalid value in Time object t
   hourRef = 30;  
   
   cout << "\nHour after modification: " << t.getHour();

   // Dangerous: Function call that returns
   // a reference can be used as an lvalue!
   t.badSetHour( 12 ) = 74;

   cout << "\n\n*********************************\n"
        << "POOR PROGRAMMING PRACTICE!!!!!!!!\n"
        << "badSetHour as an lvalue, Hour: "
        << t.getHour()
        << "\n*********************************" << endl;

   return 0;

} // end main

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