Date class definition with overloaded increment operators.

Description

Demo Code

                                                                                                                                                               
#include <iostream> 
#include <string> 
                                                                                                                                                               
using namespace std; 
                                                                                                                                                               
class Date { //  www.  j ava 2 s  .c  om
   friend ostream &operator<<( ostream &, const Date & ) ; 
public: 
   Date( int m = 1, int d = 1, int y = 1900 ); // default constructor 
   void setDate( int, int, int ); // set month, day, year 
   Date &operator++(); // prefix increment operator 
   Date operator++( int ); // postfix increment operator 
   const Date &operator+=( int ); // add days, modify object 
   static bool leapYear( int ); // is date in a leap year? 
   bool endOfMonth( int ) const; // is date at the end of month? 
private: 
   int month; 
   int day; 
   int year; 
                                                                                                                                                               
   static const int days[]; // array of days per month 
   void helpIncrement(); // utility function for incrementing date 
};
                                                                                                                                                               
                                                                                                                                                               
// initialize static member; 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 month, int day, int year ) 
{ 
   setDate( month, day, year ); 
}
                                                                                                                                                               
// set month, day and year 
void Date::setDate( int mm, int dd, int yy ) 
{ 
   if ( mm >= 1 && mm <= 12 ) 
       month = mm; 
   else 
       throw invalid_argument( "Month must be 1-12" ); 
                                                                                                                                                               
   if ( yy >= 1900 && yy <= 2100 ) 
       year = yy; 
   else 
       throw invalid_argument( "Year must be >= 1900 and <= 2100" ); 
                                                                                                                                                               
   // test for a leap year 
   if ( ( month == 2 && leapYear( year ) && dd >= 1 && dd <= 29 ) || 
         ( dd >= 1 && dd <= days[ month ] ) ) 
       day = dd; 
   else 
       throw invalid_argument( 
          "Day is out of range for current month and year" ); 
}
                                                                                                                                                               
// overloaded prefix increment operator 
Date &Date::operator++() { 
   helpIncrement(); // increment date 
   return *this; // reference return to create an lvalue 
}
                                                                                                                                                               
// 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 
}
                                                                                                                                                               
// 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 
}
                                                                                                                                                               
// if the year is a leap year, return true; otherwise, return false 
bool Date::leapYear( int testYear ) 
{ 
   if ( testYear % 400 == 0 || 
       ( testYear % 100 != 0 && testYear % 4 == 0 ) ) 
       return true; // a leap year 
   else 
       return false; // not a leap year 
}
                                                                                                                                                               
// 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 ]; 
}
                                                                                                                                                               
// 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 
       }
       else // last day of year 
       { 
           ++year; // increment year 
           month = 1; // first month of new year 
           day = 1; // first day of new month 
       } // end else 
}
                                                                                                                                                               
// overloaded output operator 
ostream &operator<<( ostream &output, const Date &d ) 
{ 
   static string 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 
}
                                                                                                                                                               
                                                                                                                                                               
int main() 
{ 
   Date d1( 12, 27, 2010 ); // December 27, 2010 
   Date d2; // defaults to January 1, 1900 
                                                                                                                                                               
   cout << "d1 is " << d1 << "\nd2 is " << d2; 
   cout << "\n\nd1 += 7 is " << ( d1 += 7 ); 
                                                                                                                                                               
   d2.setDate( 2, 28, 2008 ); 
   cout << "\n\n  d2 is " << d2; 
   cout << "\n++d2 is " << ++d2 << " (leap year allows 29th)"; 
                                                                                                                                                               
   Date d3( 7, 13, 2010 ); 
                                                                                                                                                               
   cout << "\n\nTesting the prefix increment operator:\n" << "    d3 is " << d3 << endl; 
   cout << "++d3 is " << ++d3 << endl; 
   cout << "  d3 is " << d3; 
                                                                                                                                                               
   cout << "\n\nTesting the postfix increment operator:\n" << "    d3 is " << d3 << endl; 
   cout << "d3++ is " << d3++ << endl; 
   cout << "  d3 is " << d3 << endl; 
}
Date class definition with overloaded increment operators. - C++ Class

Description

Demo Code

Result

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