Debugging Stratgies

1.15 Code High School Debugging Strategies

By Kevvin Hankins

Standard

​IT-CSP-6

Create programs that translate human intention into computational artifacts including music, images, visualizations, and more while exploring the concepts, techniques and development used in writing programs.

Locate and correct errors in a program.

​IT-CSP-6.4

Evaluate, justify, and explain a program for correctness, i.e., program style affecting the determination of program correctness.

​IT-CSP-6.3

Learning Targets

Debugging is fixing a problem in your code.

​DeBugging

A bug is a problem in your code.

​Bug

Key Vocabulary

Match

Match the term to the correct definition.

• Bug

• Debugging

• IT-CSP-6.4

A problem in your code.

Fixing a problem in your

Locate and correct errors in a program.

• A problem in your code.

• Fixing a problem in your

• Locate and correct errors in a program.

Open Ended

1. What are some bugs you’ve encountered in your programs?
2. How did you find the location of the bug?
3. What did you do to fix the bug? How did you know to do this?

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Multiple Choice

Which of the following is an example of a ‘runtime error’?

I. Karel crashing into a wall
II. Leaving a semicolon off the end of a command
III. Using the wrong syntax in an if/else statement
IV. Not closing all open brackets

• I.

• I. and III.

• II and IV

• I-IV-All

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Debugging
Basics

First Debugging Strategies

● Attention to detail

○

Even the smallest syntax error could be the source of the
problem, something as small as a typo!

● Questioning assumptions

○

Sometimes the thing we are so sure can’t be the source of
the problem actually is. Make sure to question everything.

Attention to Detail

● We need to get the details exactly right!
● But it is easy for things to slip by

○

Look out for typos

○

Small errors
■

Typos in variable names

■

Syntax errors in functions, if statements, loops

■

Valid code that isn’t what you meant

■

Accidental mix-ups

Questioning Assumptions

● The computer isn’t likely making a mistake, it is just

doing what you told it to do.

● This means we may have (and likely did!) overlook

something
○

The problem description

○

Our pre and post conditions

○

Does this actually do what I think it does?

○

What have I assumed worked that could actually be
broken?

The bug can be a simple fix!

Tricky bugs often have simple
sources.

The first step is just to
double-check your code!

Let’s debug a

problem together!

Multiple Choice

The following code contains an error. What line is it on?

• Line 3

• Line 4

• Line 5

• Line 9