Debugging

Question 1

Bug

Answer 1

• is not any error
• failure, fault, error
• infinite loop(failure)
• deadlock (failure)
• incorrect output (failure)
• memory leaks (failure)
• runtime exception

Question 2

Segmentation Fault

Answer 2

-program try’s to access memory that is not available (outside accessible range)

Question 3

Bus fault

Answer 3

-program tried to access misaligned data item

Question 4

Illegal instruction

Answer 4

-try to execute an unassigned or privileged opcode

Question 5

Bug classification

Answer 5

• A : algorithm ~ code follows the infect of the programmer but intent was wrong
• D : data ~ code reads/writes incorrect data or accessed a wrong storage location
• F : Forgotten ~ a missing action/statement or maybe put in wrong place
• B : Blunder ~ algorithm was correct but it was implemented wrong

Question 6

Blunder

Answer 6

• variable (wrong var name)
• expression (incorrect written expression)
• language (mistake encouraged by language syntax)

Question 7

Whose bug

Answer 7

Goes away when try to observe it

Question 8

Bug detection

Answer 8

1: study the failure systems, add exception handler
2: read and re-read in error location, have someone else read code, or someone who will listen
3: experiment to find the simplest way to identify
4: try inserting, verifying of the code is working as it should

Question 9

Crash dumps

Answer 9

Debugger helps discover where program crashed and why, inspect call stack, and values of vars

Question 10

Static tools

Answer 10

Crash dump inspection

Question 11

Dynamic tools

Answer 11

Debugger

Question 12

Debugger monitoring facilities

Answer 12

• breakpoint: break main
• single step execution: step over line you don’t want to go through
• inspect vars: use where or print vars
• display source code: list main
• fault detection: throws exception
• watchpoints: watch when var changes
• multithread/ multiprocess support: monitor execution of threads

Question 13

Failure

Answer 13

Something visible to the programs user

Question 14

Fault

Answer 14

The state of the program which leads to a failure

Question 15

Error

Answer 15

The incorrect code fragment which leads to the fault and thus to the failure