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

Tuesday February 24, 1998

Assigned Reading:

• A Book on C: 2.2
• Programming Abstractions in C:

Handouts (available on-line):

Topics Covered:

• We looked one more time at the majority program and emphasized again at the need to think clearly and argue convincingly that a program is correct.

• Introduced the Backus-Naur Form for describing syntax. (See Section 2.2 of A Book on C.)

• We build a calculator program that considers operator precedence of * over + and works with nested parentheses. Another feature of this program is its ability to report errors (and point to the location of the syntax error). See sample run.

  The calculator program is divided into 2 parts. The parser works with higher level concepts (expressions, terms and factors). The parser essentially follows the derivation rules for a legal arithmetic expression.

  The tokenizer does the string and character manipulations for the parser. As usual, the functions provided by the tokenizer and the types used by the tokenizer is given in a header file.