Tracing an Algorithm

What You Will Learn:

• • What is a trace table

  • How to construct a trace table

Trace Table

A trace table is a technique used to test algorithms in order to verify that no logical errors occur while an algorithm is being processed. The table usually takes the form of a multi-column, multi-row table with each column showing a variable, and each row showing each number input into the algorithm and the subsequent values of the variables.

Trace tables are typically done on paper.

Trace tables are used to test the logic of pseudocode before it is implemented in a high-level language. They are also used to debug code in a program that is not working.

The trace table shows the contents of each variable at each stage of the loop. The table also shows that when the loop is finished the variable A will contain the value 120.

Resources:

• Knowledge Organiser - Introduction to Python

• Writing algorithms using trace tables

• Trace Table classwork - example (hard copy)

• Trace tables Classwork - Questions Solutions

Homework assignment

• Trace tables - Exam questions (hard copy)