fig20_16.cpp

C程序设计经典教程第5版程序示例,比较适合初级c语言的学生

// Fig. 20.16: fig20_16.cpp
// Demonstrating a public member function that
// returns a reference to a private data member.
#include <iostream>
using std::cout;
using std::endl;

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

int main()
{
   Time t; // create Time object

   // initialize hourRef with the reference returned by badSetHour
   int &hourRef = t.badSetHour( 20 ); // 20 is a valid hour

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

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

   cout << "\n\n*************************************************\n"
      << "POOR PROGRAMMING PRACTICE!!!!!!!!\n"
      << "t.badSetHour( 12 ) as an lvalue, invalid hour: "
      << t.getHour()
      << "\n*************************************************" << endl;
   return 0;
} // end main

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