Debugging (2)

Review

• We're studying debugging, particularly debugging with a debugger.
• A few hours of time learning how to use a debugger will save you dozens of hours putting in and removing print statements (or doing whatever you choose to do).
• I use gdb for my C programs. Some folks like a visual environment, like ddd (which is layered on top of gdb).
• I think debugging in isolation is a bit weird, so we'll do things in context.

Example: Lists

• We're going to write a sample program that deals with lists (implemented as doubly-linked lists).
• Given my past experiences, it's likely that there will be bugs in our program.
  • Not least because I've included some.
• It may take us two classes to write and debug.
• Disclaimer: What we're working with is (a) the code I prepared as part of an assignment for CSC 161 and (b) some incorrect additions to that code.

A List Interface

• What is a list?
  • I want your answers
  • We'll talk generally and then in terms of a particular implementation
• In the ideal world, lists have multiple cursors that you can use to iterate through the list (with each cursor potentially at a separate point).
  • We're going to do a simpler (but less ideal) design: We'll just keep track of a current element in the list.
• Let's build an interface that focuses on the basic operations for lists - the ones that are required for other operations and that deal with the interals.

Utilities

• Things that can be built with the basic operations, e.g., print the list.

The Basic Structs

• What do they look like?

Unit Tests

• You'll summarize.
• Then we'll look at some I've written.