UMBC CMSC202, Computer Science II, Spring 1998, Sections 0101, 0102, 0103, 0104 and Honors

Tuesday March 10 1998

Assigned Reading:

• A Book on C:
• Programming Abstractions in C:

Handouts (available on-line): none

Topics Covered:

• More discussion on Project 3.
  • We paid special attention to the implementation notes and the submission instructions.
  • Also, mentioned the existence of the Project 3 notes page.
  • Simple sample files are available to test your projects. They are in the directory ~chang/pub/cs202/proj3/ on the GL file system. The sample main program checks the sparse matrix operations on these simple test cases. The README file explains all.
  • You can also find the source code for a program that generates random sparse matrices.
  • You can use the implementation of the dense matrix operations to test your sparse matrix functions on large matrices. A sample main program shows how. (See also: Header file for dense matrix operations.)

• We discussed how the DCrashOnNull() function in dense.c uses void * pointers. In this case, it is convenient to forget about the types of pointers. We also examined in detail the use of the free() function in the FreeDense() function.

• Long discussion about Abstract Data Types and what they are good for. We looked at an example of a main program that uses two abstract data types adt1 and adt2. In the implementations of these two ADT's, adt1.c and adt2.c, (which in this simple case, just involves a few integer variables), we have some private functions and some public functions. Private functions are designated by the keyword "static". Since private functions can only be used by other functions in the same file. Thus, there is no difficulty with the fact that both ADT implementations contain a function called non_unique_func_name(). The sample run shows that the functions in adt1.c call the non_unique_func_name() defined in adt1.c and the functions in adt2.c use the one defined in adt2.c. Similarly, private global variables can have the same name. Private global variables are also declared using the keyword "static". Attempts to access private global variables from the main program results in compilation errors.