Attribute-Value Lists

CSC 7000-002 Algorithms & Programming
Fall 1999, Mendel 115
Dr. David Matuszek

The idea of this assignment is to build an attribute-value list ADT (Abstract Data Type). The purpose of this assignment is to give you additional practice with recursion, and to teach you about ADTs and multifile C programs.

An attribute-value list (or A-V list) is a linked list of string pairs, where one string is called the attribute and the other string is the value. (If you want to put numeric values in an A-V list, just convert them to strings first.) For example, an attribute might be "color" and its associated value might be "red." We will require that every A-V list has an attribute name with a non-NULL value--you should make sure this is always the first A-V pair in the list.

Implement the following operations on A-V lists:

• Create an A-V list with a given value for its name attribute.
• Look up the value of an attribute on an A-V list. If the attribute isn't present, return NULL.
• Add an attribute-value pair to an A-V list. However,
  • If the attribute is already on the list, don't add it again; just replace its old value with the new one.
  • [Optional] If the new value is NULL, delete the attribute-value pair from the list (and free() the storage used by the pair and the strings).
  • The name attribute will never be modified or deleted.
• Neatly print an A-V list.

Put your code in three files:

• avlist.h contains any struct declarations, function prototypes, and #define statements that outside code might wish to access. It must not contain any definitions (declarations that also reserve storage) or any executable code.
• avlist.c contains all the A-V list function definitions. It also needs a line that says include "avlist.h" . It could (but probably won't) contain additional struct definitions, function prototypes, and #define statements that you do not want to make generally available to outside code.
• A third file contains your main() program, and also needs a line that says include "avlist.h" . This main program will be a throwaway program used for testing your A-V functions.

It is your responsibility to provide output that demonstrates all the features of your program and that can be easily graded.

You will be graded more strictly than in the past on (1) following directions, (2) good style,(3) good comments, and (4) appropriate use of functions. In addition, your program will be examined for any obvious memory leaks.