date1.cpp

经典的<<C how to program>一书第三版的例程。非常适合于C的初学者。

// Fig. 17.4: date1.cpp
// Member function definitions for Date class.
#include <iostream>

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

#include "date1.h"

// Constructor: Confirm proper value for month;
// call utility function checkDay to confirm proper
// value for day.
Date::Date( int mn, int dy, int yr )
{
   if ( mn > 0 && mn <= 12 )       // validate the month
      month = mn;
   else {
      month = 1;
      cout << "Month " << mn << " invalid. Set to month 1.\n";
   }

   year = yr;                      // should validate yr
   day = checkDay( dy );           // validate the day

   cout << "Date object constructor for date ";
   print();         // interesting: a print with no arguments
   cout << endl;
}

// Print Date object in form  month/day/year
void Date::print() const
   { cout << month << '/' << day << '/' << year; }

// Destructor: provided to confirm destruction order
Date::~Date()
{ 
   cout << "Date object destructor for date ";
   print();
   cout << endl;
}

// Utility function to confirm proper day value
// based on month and year.
// Is the year 2000 a leap year?
int Date::checkDay( int testDay )
{
   static const int daysPerMonth[ 13 ] = 
      {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

   if ( testDay > 0 && testDay <= daysPerMonth[ month ] )
      return testDay;

   if ( month == 2 &&      // February: Check for leap year
        testDay == 29 &&
        ( year % 400 == 0 ||                      
         ( year % 4 == 0 && year % 100 != 0 ) ) )
      return testDay;

   cout << "Day " << testDay << " invalid. Set to day 1.\n";

   return 1;  // leave object in consistent state if bad value
}



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 * (C) Copyright 2000 by Deitel & Associates, Inc. and Prentice Hall.     *
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