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

Tuesday January 27, 1998

Assigned Reading:

• A Book on C: 6.1-6.6 and 11.1-11.5
• Programming Abstractions in C: 2.1-2.5 and 3.4

Handouts (available on-line): course description, syllabus and project policy.

Topics Covered:

• Prerequisites for CMSC 202: See FAQ on Introductory Computer Science Courses on material that you are expected to know from CMSC 201. For example, you should really understand parameter passing by reference.
• Noted the existence of the course web page, which you already know about if you are reading this page. (Reminder: check in if you haven't already.)
• Went over course description. Note: the Roberts textbook is optional. Also, you will be required to purchase Dr. Mayfield's excellent notes on pointers "Understanding Pointers in C" for $6.50. The notes will be available in the bookstore shortly.
• Went over course syllabus and project policy. NB: I'm serious about catching cheaters on the projects. Read over the course policy on cheating well.
• Motivational lecture on how to learn advanced programming skills. Main point: you should be able to sort out the syntactic issues by now. In this course you need to consider higher-level issues in data structures and problem-solving strategies.
• One way to learn how to use new features in a programming language is to understand simple programs and learn how to generalize from the simple example. In the following sequence of programs, we first examine the use of parameter passing by reference for integers. We also examine a simple program that uses structures. From the two, we are able to concoct a program that passes structure parameters by reference.
  • A simple function: program and sample run.
  • A simple function with an integer reference parameter: program and sample run.
  • A simple program that uses structures: program and sample run.
  • A simple function that takes a structure as a parameter and returns a structure value: program and sample run.
    Note that the syntax in this function is not much different from the syntax for the function which takes an integer parameter and returns an integer value.
  • A revision of the previous function which fixes a problem where the minute field might exceed 59 minutes: program and sample run.
  • Finally, we write a function that takes a structure reference parameter. program and sample run.
    This function fixes the minute field of the parameter if the field exceeds 60 minutes. Note that the syntax for accessing the field of the structure parameter is (*p).minute. The parentheses are necessary because the . operator has a higher precedence than the dereference * operator. C provides a short cut notation, p->minute is identical to (*p).minute. Nevertheless, the mechanism for working with reference parameters is essentially the same as that of our second program.