Property List Project, Part 1

Introduction

This assignment is being done as two separate homeworks. The first half is called "Homework 5a" and is due on the day of the sixth class of the course (10/8; 10/11). The second half is called "Homework 5b" and is due the week after the exam (10/29; 10/25). [The Tuesday due date was changed to 10/15, even though there is no class that day.]

The project is to develop a package that implements a structure called a "Property List." A property list is a list of elements, each of which consists of a name, a type, and a value. Within a property list, the same name may occur multiple times, but each name-type combination must be unique. The operations defined for a property list include insert, which adds an element to the list, delete, which removes an element from the list, and getValue, which retrieves a value given a name and type.

Homework 5a is to implement the first part of an interactive program that allows a user to insert entries into a property list. Homework 5b is to implement the property list package itself.

Homework 5a

Write a program containing a function definition for main(). The program prompts the user to enter a name or a command. If the string entered is "exit" the program terminates. Otherwise, the program asks the user to enter the name of a data type. Valid responses are "int," "char," "long," "float," and "double." Depending on the type name the user enters, the program then prompts for and reads in a value of the appropriate type. The program then inserts the {name-type-value} triple into the property list, and prompts the user to enter another name or command. The process repeats until the user enters "exit" in reply to the name or command prompt.

Here is an example of the execution of this program (named plist in this example):

  qcunix1> plist
  Enter name or command: vickery
  Enter type of value: int
  Enter integer value: 100
  Integer insert: vickery 100
  Insert succeeded
  Enter name or command: vickery
  Enter type of value: float
  Enter float value: 3.14159  
  Float insert: vickery 3.14159
  Insert succeeded
  Enter name or command: exit
  qcunix1>

For this part of the assignment, I am providing you with an object module named plist.o which contains the code for a set of functions named insert(), one for each of the recognized data types. I am also providing you with a header file named plist.h that contains function prototypes for the insert() functions and a definition for an enum called types.

In the sample output above, the messages that start "Integer insert" and "Float insert" were output by the code in plist.o and all other messages were output by main().

To do this part of the project, create a project directory, change to it, and copy all the files from ~vickery/CS-200/Homework_5 into it:

  qcunix1> cp ~vickery/CS-200/Homework_5/* .

You will get one .o file, one .h file, and a Makefile. If you name your own program file main.cc, all you need to do to build an executable program named plist is to type "gmake" (no arguments needed).

You can type "gmake clean" to delete unneeded files from the project directory before you submit it.

Notes:

You must put a "#include "plist.h" statement in your main.cc file, and your calls to insert() must match the prototypes given in plist.h. This means that you must use the enum for types that I provided. Look in plist.h to see how this was set up. (Tuesday students: I changed the names of the enum values from "INT," etc. as given in class to "T_INT," etc.)

Your program must check that the user enters a valid data type name and not prompt for a value until the type name is valid (or the user types ^C to abort the program!). Optional: display a list of valid type names if the user enters something invalid, maybe like this:

  qcunix1> plist
  Enter name or command: vickery
  Enter type of value: garbage
  Valid types are int, long, char, float, double, 
  Enter type of value: int
  Enter integer value: 100
  Integer insert: vickery 100
  Insert succeeded
  Enter name or command: exit
  qcunix1>

Because of the way C++ stream input works, the user will be able to make your program "work funny" by doing such things as typing more than one character when prompted for a char value. A particularly annoying "feature" is that the program will go into an endless loop displaying all its prompt messages over and over if the user types character(s) instead of numbers when prompted for a numeric value. There is no way to get around these problems using the parts of the language that we are using now, so we will just accept as a requirement that the user must type values in correctly. Use ^C if your program goes into that endless loop, by the way.
Put a text file in man page format in your project directory before you submit the program. As described in the project management web page for this course, this is a small text file that tells users how to use the program. Be sure to type this file in the proper format. (See the web page.)

Homework 5b

Don't work on this part of the assignment yet. There is a Separate Web Page for it.

Dr. Christopher Vickery
Computer Science Department
Queens College of CUNY
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