date.cpp

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// Fig. 11.13: Date.cpp
// Date class member-function definitions.
#include <iostream>
#include "Date.h"

// initialize static member at file scope; one classwide copy
const int Date::days[] = 
   { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

// Date constructor
Date::Date( int m, int d, int y ) 
{ 
   setDate( m, d, y ); 
} // end Date constructor

// set month, day and year
void Date::setDate( int mm, int dd, int yy )
{
   month = ( mm >= 1 && mm <= 12 ) ? mm : 1;
   year = ( yy >= 1900 && yy <= 2100 ) ? yy : 1900;

   // test for a leap year
   if ( month == 2 && leapYear( year ) )
      day = ( dd >= 1 && dd <= 29 ) ? dd : 1;
   else
      day = ( dd >= 1 && dd <= days[ month ] ) ? dd : 1;
} // end function setDate

// overloaded prefix increment operator 
Date &Date::operator++()
{
   helpIncrement(); // increment date
   return *this; // reference return to create an lvalue
} // end function operator++

// overloaded postfix increment operator; note that the  
// dummy integer parameter does not have a parameter name
Date Date::operator++( int )
{
   Date temp = *this; // hold current state of object
   helpIncrement(); 

   // return unincremented, saved, temporary object
   return temp; // value return; not a reference return
} // end function operator++

// add specified number of days to date
const Date &Date::operator+=( int additionalDays )
{
   for ( int i = 0; i < additionalDays; i++ )
      helpIncrement();

   return *this; // enables cascading
} // end function operator+=

// if the year is a leap year, return true; otherwise, return false
bool Date::leapYear( int testYear ) const
{
   if ( testYear % 400 == 0 || 
      ( testYear % 100 != 0 && testYear % 4 == 0 ) )
      return true; // a leap year
   else
      return false; // not a leap year
} // end function leapYear

// determine whether the day is the last day of the month
bool Date::endOfMonth( int testDay ) const
{
   if ( month == 2 && leapYear( year ) )
      return testDay == 29; // last day of Feb. in leap year
   else
      return testDay == days[ month ];
} // end function endOfMonth

// function to help increment the date
void Date::helpIncrement()
{
   // day is not end of month
   if ( !endOfMonth( day ) )
      day++; // increment day
   else 
      if ( month < 12 ) // day is end of month and month < 12
      {
         month++; // increment month
         day = 1; // first day of new month
      } // end if
      else // last day of year
      {
         year++; // increment year
         month = 1; // first month of new year
         day = 1; // first day of new month
      } // end else
} // end function helpIncrement

// overloaded output operator
ostream &operator<<( ostream &output, const Date &d )
{
   static char *monthName[ 13 ] = { "", "January", "February",
      "March", "April", "May", "June", "July", "August",
      "September", "October", "November", "December" };
   output << monthName[ d.month ] << ' ' << d.day << ", " << d.year;
   return output; // enables cascading
} // end function operator<<

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