Dynamic Memory Allocation Example

#include <iostream.h>
#include <string.h>
/******************************************************************
 File: class7.C
 Instantiate an appointment class object. Initialize it using
 a constructor.  Set an appointment and display the appointment.
 The appointment class is composed of a date object and a time
 object. 
******************************************************************/

class date {
     char day_of_week[10];
     int day;
     int month;
     int year;
public:
     date();
     void set_date();
     void get_date();
};

class time {
     int hours;
     int mins;
public:
     time();
     void set_time();
     void get_time();
};

class appointment {
     date ddmmyy;
     time hhmm;
public:
     appointment();
     void set_appt();
     void get_appt();
};

date::date()
{
     cout << "Constructing date..." << endl;
     strcpy(day_of_week, "\0");
     day   = 0;
     month = 0;
     year  = 0;
}

void date::set_date()
{
     cout << "Enter day of the week, eg. Monday, Tuesday...: ";
     cin >> day_of_week;
     cout << "Enter date in DD MM YYYY format: ";
     cin >> day >> month >> year;
}

void date::get_date()
{
     cout << "The date stored in this object is:" << endl;
     cout << "Day of the week: " << day_of_week << endl;
     cout << "Day: " << day << endl;
     cout << "Month: " << month << endl;
     cout << "Year: " << year << endl;
}

time::time()
{
     cout << "Constructing time..." << endl;
     hours   = 0;
     mins = 0;
}

void time::set_time()
{
     cout << "Enter time in HH MM format: ";
     cin >> hours >> mins;
}

void time::get_time()
{
     cout << "The time stored in this object is:" << endl;
     cout << "Hours: " << hours << endl;
     cout << "Minutes: " << mins << endl;
}


appointment::appointment()
{
     cout << "Constructing appointment..." << endl;
}

void appointment::set_appt()
{
     ddmmyy.set_date();
     hhmm.set_time();
}

void appointment::get_appt()
{
     ddmmyy.get_date();
     hhmm.get_time();
}

int main()
{
     appointment today;

     today.get_appt();
     today.set_appt();
     today.get_appt();

     return(0);
}

#include <iostream.h>
#include <string.h>
#include <stddef.h>
/******************************************************************
 File: class8.C
 Instantiate an appointment class object. Initialize it using
 a constructor.  Set an appointment and display the appointment.
 The appointment class is composed of a date object and a time
 object. Finally,the class destructors are invoked as the date 
 object goes out of scope 
******************************************************************/

class date {
     char* day_of_week;
     int day;
     int month;
     int year;
public:
     date(); // Constructor
     ~date(); // Destructor
     void set_date();
     void get_date();
};

class time {
     int hours;
     int mins;
public:
     time(); // Constructor
     ~time(); // Destructor
     void set_time();
     void get_time();
};

class appointment {
     date ddmmyy;
     time hhmm;
public:
     appointment(); // Constructor
     ~appointment(); // Destructor
     void set_appt();
     void get_appt();
};

date::date()
{
     cout << "Constructing date..." << endl;
     day_of_week = NULL; 
     day   = 0;
     month = 0;
     year  = 0;
}

date::~date()
{
     cout << "Destroying date..." << endl;
     delete [] day_of_week; 
}

void date::set_date()
{
     char in_string[10];
     cout << "Enter day of the week, eg. Monday, Tuesday...: ";
     cin >> in_string;
     day_of_week = new char[strlen(in_string)+1];
     strcpy(day_of_week, in_string);
     cout << "Enter date in DD MM YYYY format: ";
     cin >> day >> month >> year;
}

void date::get_date()
{
     cout << "\nThe date stored in this object is:" << endl;
     cout << "Day of the week: " << day_of_week << endl;
     cout << "Day: " << day << endl;
     cout << "Month: " << month << endl;
     cout << "Year: " << year << endl;
}

time::time()
{
     cout << "Constructing time..." << endl;
     hours   = 0;
     mins = 0;
}

time::~time()
{
     cout << "Destroying time..." << endl;
}

void time::set_time()
{
     cout << "Enter time in HH MM format: ";
     cin >> hours >> mins;
}

void time::get_time()
{
     cout << "The time stored in this object is:" << endl;
     cout << "Hours: " << hours << endl;
     cout << "Minutes: " << mins << endl << endl;
}


appointment::appointment()
{
     cout << "Constructing appointment..." << endl;
}

appointment::~appointment()
{
     cout << "Destroying appointment..." << endl;
}

void appointment::set_appt()
{
     ddmmyy.set_date();
     hhmm.set_time();
}

void appointment::get_appt()
{
     ddmmyy.get_date();
     hhmm.get_time();
}

int main()
{
     appointment today;

     today.get_appt();
     today.set_appt();
     today.get_appt();

     return(0);
}

Output:
Constructing date...
Constructing time...
Constructing appointment...

The date stored in this object is:
Day of the week: (null)
Day: 0
Month: 0
Year: 0
The time stored in this object is:
Hours: 0
Minutes: 0

Enter day of the week, eg. Monday, Tuesday...: Monday
Enter date in DD MM YYYY format: 21 4 1997
Enter time in HH MM format: 3 40

The date stored in this object is:
Day of the week: Monday
Day: 21
Month: 4
Year: 1997
The time stored in this object is:
Hours: 3
Minutes: 40

Destroying appointment...
Destroying time...
Destroying date...