Introduction to Debugging? What strategies include debugging?

When the software testing is successfully done, the next step is debugging. Debugging is the process of removing the error that has been uncovered during the testing process. Debugging process starts with the execution of a test case. The results that are attained are assessed and the actual and expected values are compared. Debugging is the process that matches symptom with the cause.

In debugging process, there is a possibility of two outcomes:
- cause is found and corrected.
- cause is not found

Debugging sounds difficult and here are some reasons why it is so:
- The cause and symptom may be located remotely.
- Sometimes when some other error is corrected, the symptom disappear.
- Human error can cause a symptom.
- Timing problem can cause a symptom.
- Non errors can cause symptoms.
- Symptoms can be intermittent.
- There is a possibility that causes are distributed across different tasks running on different processors.

Debugging strategy includes finding and correcting the cause of software error by the use of three strategies:
- Brute force uses the philosophy of let the computer find the error. Memory dumps are taken, run-time traces are invoked and program is loaded with output statements.
- Backtracking is the process which starts at the site where symptom is uncovered, source code is traced backward until cause is found.
- In cause elimination, cause hypothesis is devised and data is used to prove or disprove the hypothesis. On the other hand, list of possible causes is developed and tests are conducted to eliminate each.