This document discusses debugging, which is the process of finding and resolving defects in computer software or systems. It outlines the basic steps of debugging as recognizing a bug exists, isolating its source, identifying the cause, determining a fix, applying the fix, and testing it. Sources of bugs include bad design, insufficient isolation, typos, and later changes that introduce new bugs. Effective debugging involves quickly finding and fixing bugs while introducing few new ones. The document also provides an overview of using the GDB debugger, including commands like run, step, and help as well as tips on how not to debug like guessing causes or blaming others.

1. DEBUGGING
SUBMITTED BY
S.PRIYANKA
P.KALAISELVI
A.VIDYA

2. What id debugging?
Debugging is the process of finding and resolving of
defects that prevent correct operation of computer
software or a system.
 Mistake made by programmers
Also(and maybe better) called:
Errors
Defects
Faults

3. Basic Steps
Recognize that a bug exists
Isolate the source of the bug
Identify the cause of the bug
Determine a fix for the bug
Apply the fix and test it
cognize that

4. Sources of Bugs
 Bad Design
 Wrong/incorrect solution to problem
 From system-level to statement-level
 Insufficient Isolation
 Changes in one area affect another
 Typos
 Entered wrong text, chose wrong variable
 Later changes/fixes that aren’t complete
 A change in one area affects another

5. Debugging in Software Engineering
 Programmer speed has high correlation to debugging speed
 Best debuggers can be more than to 10 times as fast
 Faster finding bugs
 Find more bugs
 Introduce fewer new bugs

6. GDB- Commands
 Command names may be truncated if the abbreviation is unambiguous:
s (for step), r (for run)
 UNIX style TAB completion for the command names.
 Alternative way: complete chars.
Ex.: complete h results in: handle
hbreak
help
 Getting help:
help (or h) – lists all classes of commands.
h command - displays a short description of the command

7. GDB-Running Programs
Running a program:
run (or r) -- creates an inferior process that runs your program.
 if there are no execution errors the program will finish and results will
be displayed
 in case of error, the GDB will show:
- the line the program has stopped on and
- a short description of what it believes has caused the error

8. GDB-Running Programs continue
There is a certain information that affects the execution of a
program:
 program’s arguments
 program’s environment
 program’s working directory
 the standard input and output

9. Way NOT to Debug
 Guess at what’s causing it
 Don’t try to understand what’s causing it
 Fix the symptom instead of the cause
 Special case code
 Blame it on someone else’s code
 Only after extensive testing/proof
 Blame it on the compiler/ computer
 Yes, it happens, but almost never is this the read cause