CS 250 Computer Programming and Problem Solving - FALL 1998 

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Object Oriented Design:

Case Study: Doctor Scheduling

Version 1:

Top Down Design.

• Write PseudoCode for the "main" program
  pseudocode is a structured English which uses English nouns and verbs and C++ control structure syntax to express the way the program should work (the algorithm)

main
{
   initialize the scheduler at beginning of day
   Make appointments for the doctors for today
   Print appointments made today
   finalize at end of day
}

• Refine pseudocode into objects and member functions of those objects.
• From the above pseudocode. Need a scheduler object which takes care of appointments over a day
• This object needs to be initialized (could use the constructor for that purpose)
• This object needs to schedule appointments for the entire day
• This object needs to print appointments for today
• Let's write out the specification for what we need so far

//######################
// Scheduler is responsible for making appointments with patients
// and recording them in the doctor's daily schedule
// and Printing out these schedules
// keeps a reference to all doctors for this purpose
//######################

class Scheduler {
public:
  Scheduler( Doctor * docs, int NumDoctors);
  // Scheduler keeps track of appointments for all doctors
  // A list of doctors is passed and a reference to this list is kept
  // in this object

  void PrintAllAppointments( const char * fileName );
  // PRE: fileName is a legtimate file name
  // POST: the daily schedule of all doctors is printed to "fileName"

  void ScheduleAllAppointments(); 
  // runs all day scheduling appointments
  // returns when all patients have be scheduled for this day

private:
  Doctor * doctors;  // points to first element in array of doctors 
  // notice that there is only one copy of the doctor object, but we can
  // refer to it using the pointer and so can update the doctor/s schedule
  // we could have made a copy of the doctor objects - 
  // but then they could not be accessed or changed outside (consistently)
 int NumDoctors; // keeps size of array of Doctors
};

• Now you can refine the pseudocode into real C++ code
• Or you can write pseudocode for the member functions
• Let's do the main program real code first (notice the pseudocode has become comments)

#include "doctors.h" // contains all specifications


int main()
{
   const int NumDoctors = 5; // Keep the Doctor objects here	
   Doctor doctorArray[NumDoctors];
   cout << "Doctors Office Scheduling Program\n\n";
	
   //initialize the scheduler at beginning of day
   Scheduler officeSchedule( doctorArray, NumDoctors );
   	
   //Make appointments for the doctors for today
   officeSchedule.ScheduleAllAppointments();
   //Print appointments made today
   officeSchedule.PrintAllAppointments( "appts.txt" );

   //finalize at end of day
   return 0;
}

• What would it take to get this to at least compile?

// in doctor.h add minimal Doctor class
class Doctor{ 
public:
   Doctor();
};

// in doctor.cpp, add empty function definitions
Doctor::Doctor(){}
Scheduler::Scheduler( Doctor * docs, int num ) {}
void Scheduler::PrintAllAppointments(const char * fileName) {}
void Scheduler::ScheduleAllAppointments() {}

(here is the code at this point)

Copyright chris wild 1998.
For problems or questions regarding this website contact [Chris Wild (e-mail:wild@cs.odu.edu].
Last updated: October 05, 1998.