Lecture 3 Objectives

KNOW:

• that the DrRacket function check-expect can be used to automate testing
• that tests should be written before the function is defined
• that cond is the way to ask a true/false question in a DrRacket program
• that DrRacket has a boolean data type to represent true/false values
• that words can be represented as strings in a DrRacket program

BE ABLE TO:

• write test cases for a function using check-expect
• write a DrRacket program that makes a decision using cond
• write a DrRacket program that consumes and/or produces strings

Sample Exam Question:

Write a DrRacket function called sign that consumes a number, and returns one of the words positive, negative, or zero depending on the sign of the number. For example,

(sign -2)

would return "negative"

Comment your function with a contract and purpose, and write a set of test cases for your function.