CIS 122: Assignment #6

Reading:

Chapters 11, 14.1-3, 14.5, 18 and 19

Putting it all Together: Use/improvement of an appointment book class

(touching on diverse themes of information hiding, encapsulation, and interface, as well as file I/O, sorting, and search)

The ability to define object data types (i.e., classes) provides a powerful mechanism for abstraction in problem solving. By tightly controlling the state of every instance through a class's public interface, the implementation remains truly opaque. The programmer using such a class need only understand how to call the publicly-available methods and understand what their behavioral guarantees are, the knowledge of which is often available from the header file alone. In this way, the individual elements of an object's state become irrelevant from outside the implementation, facilitating the understanding of the object as a single, coherent data value.

This level of abstraction offers two advantages to the programmer. On the one hand, she need not be responsible for maintaining the relationships among an object's component variables that are necessary for a valid state. The second advantage follows from this: by considering the defining class only as an abstract data type, it becomes easier to write sometimes complicated algorithms that manipulate object values of this type. This is important, since many important algorithms were developed independently of a particular class implementation, and since particular tasks we want to perform on an object (e.g. comparison) may be quite complicated.

For example, consider the problem of comparison between between values. As we discussed in class, comparison can mean a number of things (lexicographic, alphabetic, numeric, reverse numeric, etc.). For a class such as Time, even the usual sense of comparison can be difficult to get right:

int Time::compare(Time d) {
  /* returns -1, 0, or 1, according to whether this Time is less than, equal 
     to, or greater than d
  */

  int this_hour = hour, d_hour = d.getHour(); /* One subtlety:  12 pm is noon,
                                                 and thus earlier than all 
                                                 other pm times.  Similar for
                                                 midnight. */
  this_hour %= 12;
  d_hour %= 12;
 
  if (merid < d.getMer())       return -1;
  else if (merid > d.getMer())  return  1;
  else if (this_hour  < d_hour) return -1;
  else if (this_hour  > d_hour) return  1;
  else if (min   < d.getMin())  return -1;
  else if (min   > d.getMin())  return  1;
  else 
}

Details like this are best ignored when one simply needs to make a comparison of two Time objects as part of a more complicated activity such as sorting.

Your Job ...

... is to complete the code in a test driver for the ApptBook class, which provides an implementation of a simple appointment book. The files provided for this project are the following:

• datetime.h -- Header file, with documentation, for the Time and Date classes
• apptbook.h -- Header file, with documentation, for the Appointment and ApptBook classes
• datetime.cpp -- Implementation of the Time and Date classes
• apptbook.cpp -- Implementation of the Appointment and ApptBook classes
• testApptBook.cpp -- driver program to test ApptBook
• appts.dat -- Data file for use with testApptBook.cpp

All files can be found in the directory

 
  http://www.cs.uoregon.edu/classes/cis122/code/hw6/

For testApptBook, your task is twofold:

1. I/O: Several statements crucial to successful use of the ifstream and ofstream objects have been left undone, and are marked in the code with ????. Fill these in as appropriate.
2. selSort(): Complete the body of this function by implementing a selection sort, defined on a vector of Appointment objects.

Extra Credit

The ApptBook implementation in apptbook.cpp includes a private find method, which is used in several methods to help ensure that no duplicate Appointment values are stored. Currently, the body of this method implements a linear search.

However, we can do better than this. Because of the way that new Appointment values are added (using another private method, insert), the list of appointments is always stored in sorted order. Consequently, we could have implemented find to use a binary search.

For extra credit, make this modification.

Compile and Test

Make sure that all six files are in the same directory. Then compile with the following command:

   g++ -o testApptBook testApptBook.cpp datetime.cpp apptbook.cpp

Test your program by running it. If successful, you will have two files, "appts-2.dat" and "appts_sched.txt", each of which contains 18 appointments, sorted in chronological order.

Turn in:

• Your completed testApptBook.cpp
• Your modified apptbook.cpp, if you did the extra credit

Since you won't be making changes elsewhere, don't bother submitting any of the other files.

Submit your source code file as a plain text email attachment, sent to me at johnfl@cs.uoregon.edu. Please avoid paper copies. The full source of apptbook.cpp is particularly unwieldy.