1. Tracing
What, How, and Why
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2. What?
Tracing is the simulation of a computer program or part of a computer program
We “play computer”
The results should be the same as if the program were executed on a real machine
The simulation needs to cover every relevant aspect of the computation
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3. Elbonian Computers
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4. Why? Essential debugging tool Important learning technique
A correct trace demonstrates that you understand the fundamentals
We will have tracing exercises in class and on tests
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5. How? Find the first statement to be executed
Write down all the variables
Used to record their current value
As new variables are encountered they may be added to the list
For each statement that is encountered:
Determine its action
Record changes to any variables
Show the final values when execution is complete
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6. An example Java Console C++ Java Window
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7. Right and Wrong There is a right way and a wrong way to do tracing
The right way is this
The wrong way is to attempt to analyze this algebraically
That approach does not allow for a change in variables
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