2. Debugging By: Issam Benstitou Khouloud Mrabet Samir NAQOS supervised by Dr Kettani D.

3. Outline I.Introduction II.Debugging: Definition III.What causes debugging ? IV. A formal approche to debugging. V.Debugging in the life cycle. VI.The debugging process. VII.Debugging Approaches VIII.Conclusion.

4. Introduction n Team presentation n Context presentation

5. Debugging Definition: Pressman Jazayri et al

6. What causes debugging ? Software Faults: Is an erroneous portion of a software system which may cause failures to occurs if it is run in a particular state, or with particular inputs. Software Failures is an execution event where the software behaves in an unexpected or undesirable way.

7. What causes debugging ? (cont.) Defect (bug) : Each occurrence of the program design or the program code that fails to meet a specification.

8. Debugging: A formal Approache Debugging, testing and verification Formal Definition of:  Debugging  Testing  verification

9. When does it occurs in the life Cycle

10. Debugging Process Two possible outcomes: -The cause will be found -The cause will not be found

11. The process of Debugging

12. Characteristics of Bugs that provide some hints - The symptom and the cause may be Geographicall isolated -The symptom may disappear when another Error is corrected -The symptom may be caused by nonerrors

13. Characteristics of Bugs that provide some hints -It may be caused by human errors -The symptom may be a result of timing problems rather than processing problems. - -It may be difficult to accurately reproduce input conditions.

14. Debugging Approches n Bradley description: … The basis of debugging is to locate the problem’s source by binary partitioning, through working hypotheses that predict new values to be examined.

15. Debugging Approaches n The Brute Force n Bracktracking n Cause Elimination

16. Debugging Approaches n Is the cause of the bug reproduced in another part of the program? n What next bug might be reproduced by the fix I am about to make? n What could we have done to prevent this bug in the first place?

17. Conclusion n Shneiderman states: “…Debugging is one of the more frustrating parts of programming. It has elements of problem solving or brain teasers, coupled with the annoying recognition that you have made a mistake…”