Debugging

Updated 22 Jul 2026

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def
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  the process that results in the removal of an error discovered through testing
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  always occurs as a consequence of testing, but is not testing itself
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process
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  examine test results to find a lack of correspondence between expected and actual behavior
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  attempt to match the symptom with its cause
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  correct the error
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two possible outcomes
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  the cause is found and corrected
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  the cause is not found (leads to further investigation and iteration)
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why debugging is difficult
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  the symptom may disappear temporarily when another error is corrected
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  the symptom may be caused by non-errors (e.g., rounding inaccuracies)
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  the symptom may be caused by hard-to-trace human errors (wrong input, wrong system configuration)
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  the symptom may result from timing problems rather than logic problems
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  it may be difficult to accurately reproduce input conditions
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  the symptom may be intermittent (common in embedded systems coupling hardware and software)
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  the symptom may be distributed across tasks running on different processors
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  pressure to fix bugs quickly can cause a developer to introduce new bugs while fixing one
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debugging strategies
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  brute force — exhaustive dump or trace of the program; most common but least efficient
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  backtracking — work backward from the symptom to the source of the error
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  cause elimination — hypothesize potential causes and test each one systematically
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questions to ask before correcting an error
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  is the cause of this bug reproduced in another part of the program?
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  what "next bug" might be introduced by the fix I'm about to make?
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  what could have been done to prevent this kind of bug earlier?
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related
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  Software Testing
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  White Box Testing

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