CS 250 Computer Programming and Problem Solving - FALL 1998 

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Object Oriented Design:

Case Study: Doctor Scheduling

Version 2:

• Now let's work on pseudocode for Scheduler member functions
• We will do the constructor first
• Decision: Keep information on each doctor in a file

Scheduler::Scheduler(Doctor * docs, int NumDoctors)
{
   initialize private data members from parameters
   open file containing Doctor Object information
   for all doctors
      read that doctors information
}

• Decision: Let each doctor object be responsible for reading this file for their information
• Let's overload the extraction I/O operator for this purpose
• SO let's refine the constructor

// Initialize 
// array of doctors from a file.

Scheduler::Scheduler( Doctor * docs, int num )
{
  // initialize private data members from parameters
  doctors = docs;
  NumDoctors = num;
  // open file containing Doctor Object information
  ifstream dnameFile( "doctors.txt" );
  if( !dnameFile )
  {
    cout << "Cannot open input file! Aborting program.\n";
    abort(); // Needs #include <stdlib.h>
  }
  // for all doctors
  for(int i = 0; i < NumDoctors; i++)
  {
      // read that doctors information
     dnameFile >> doctors[i]; // read in information to initialize i'th doctor
  }
}

• To get this to compile, need to define overloaded extraction operator for Doctor
• This also means we need to define the format for the "doctors.txt" file
• DECISION: all we need is doctor's name in the file stored as "LastName, FirstName"
• Here are changes to Specification for Doctor

class Doctor {
	friend istream & operator >>(istream & inputFile, Doctor & thisDoc);
public:
  Doctor();
private:
  Name name;
};

• And to the implementation file for Doctor
  (Why not just use overloaded Name extraction operator?)

istream & operator >>(istream & inFile, Doctor & thisDoc)
{
	char temp[100];
	inFile.getline(temp,100,','); 
	thisDoc.name.SetLast(temp); 
	inFile.getline(temp,100,'\n');
	thisDoc.name.SetFirst(temp);
	cout << thisDoc.name; // for debugging purposes
	return inFile;
}

• After adding the necessary include files, it will compile
  (here is the sourcecode)
• How do we know this works?
  Could add cout statements to make sure it is reading the doctors.txt file OK

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.