The Art of Debugging.pptx
- 1. The Art of Debugging Dr. S. Karthigai Selvi Guest Teacher Department of Computer Science and Applications The Gandhigram Rural Institute – Deemed to be University, India [email protected]
- 2. What is debugging? Testing process results uncover processes and errors. Debugging is the process of removing the errors. It reveals the area where the correspondence between aim and testing result. It is a series of process and produces two outcomes (1) the cause will be found and corrected or (2) the cause will not be found.
- 3. characteristics of bugs provide some clues: 1. That is, the symptom may appear in one part of a program, while the cause may actually be located at a site that is far removed. Highly coupled components increase this situation. 2. The symptom may disappear (temporarily) when another error is corrected. 3. The symptom may actually be caused by non- errors (e.g., round-off inaccuracies). 4. The symptom may be caused by human error that is not easily traced.
- 4. 5. The symptom may be a result of timing problems, rather than processing problems. 6. It may be difficult to accurately reproduce input conditions (e.g., a real-time application in which input ordering is indeterminate). 7. The symptom may be due to causes that are distributed across a number of tasks running on different processors.
- 5. Psychological Considerations Debugging process ability arises based on experience and interest. Somebody feels frustration Cannot accept errors
- 6. Debugging Strategies Debugging is a straightforward application of the scientific method that has been developed over 2,500 years Based on working hypotheses partition the software into two or more, then debug the programs Three debugging strategies were proposed by Mye
- 7. Strategies are Brue Force: Isolate errors by memory dumps are taken, run-time traces are invoked, the program is loaded with output statements. Any one clue is identified in the above activities and entire program will be debugged It consumes more time Debugging Cause Elimination Backtracking Brute Force
- 8. Backtracking: Most common method for small programs The errors are backward traced manually Drawback: if no of lines increased the detection will difficult Cause elimination: Introduces binary partitioning A “cause hypothesis” is devised and the aforementioned data are used to prove or disprove the hypothesis. a list of all possible causes is developed and tests are conducted to eliminate each
- 9. Automated debugging debugging approaches can be supplemented with debugging tools that can provide you with semi-automated support as debugging strategies are attempted. Integrated development environments (IDEs) provide a way to capture some of the language specific predetermined errors (e.g., missing end-of-statement characters, undefined variables, and so on) without requiring compilation.” A wide variety of debugging compilers, dynamic debugging aids (“tracers”), automatic test-case generators, and cross- reference mapping tools are available. However, tools are not a substitute for careful evaluation based on a complete design model and clear source code.
- 10. Correcting the Error Once a bug has been found, it must be corrected. Before making the “correction” that removes the cause of a bug: Is the cause of the bug reproduced in another part of the program? a program defect is caused by an erroneous pattern of logic that may be reproduced elsewhere. Explicit consideration of the logical pattern mayresult in the discovery of other errors. What “next bug” might be introduced by the fix I’m about to make?
- 11. What could we have done to prevent this bug in the first place? Before the correction is made, the source code (or, better, the design) should be evaluated to assess coupling of logic and data structures. If the correction is to be made in a highly coupled section of the program, special care must be taken when any change is made. What could we have done to prevent this bug in the first place? If you correct the process as well as the product, the bug will be removed from the current program and may be eliminated from all future programs.
- 12. Thank you