chapter 12

Question 1

software development life cycle (SDLC)

Answer 1

a process of developing a program, set out in defined stages. the five stages are analysis, design, coding, testing, and maintenance.

Question 2

analysis

Answer 2

the problem is clearly defined, and a solution is planned. a program specification is produced. you decide on how to solve the program (top-down or bottom-up)

Question 3

design

Answer 3

an identifier table is created, showing variable names, data types & explanations/descriptions. data structures are defined. the algorithm is planned using pseudocode, flowcharts and structure charts and the program is split into its modules

Question 4

coding

Answer 4

you choose a suitable high-level language and create code and programs for each module.

Question 5

testing

Answer 5

uses a variety of testing strategies to ensure the program works as stated in the specification. eliminates syntax, logic and run-time errors. dry runs, test plans and trace tables are created

Question 6

maintenance

Answer 6

occurs once the program is in full operation i.e. during use and ensures it continues to work correctly. deals with software upgrades, bug fixes, and repairs. there are three types of maintenance: adaptive, corrective, and perfective

Question 7

three development models

Answer 7

waterfall, iterative, RAD

Question 8

waterfall

Answer 8

linear, sequential model of development. Each stage is completed and signed off before the next stage begins. Fully documented at each stage.

Question 9

iterative

Answer 9

development starts with a small subset of program requirements, and repeated reviews are used to identify further requirements until a complete program is eventually made. stages 2-3 are repeated.

Question 10

rapid application development (RAD)

Answer 10

developing different parts of the program in parallel by teams of programmers. uses prototyping and high customer involvement

Question 11

finite state machine

Answer 11

A finite state machine (FSM) is a machine that consists of a fixed set of possible states, inputs to change the states, and a set of outputs.

Question 12

state transition diagram

Answer 12

state-transition table gives information about inputs and events
* states are represented as circles
* transitions are represented as arrows
* events are represented as arrow labels
* stopped state is indicated by a double circle

Question 13

accepting state

Answer 13

state a system reaches when input is valid

Question 14

event

Answer 14

something that can happen in a system that may trigger the transition to another state

Question 15

guard

Answer 15

condition a condition that must be met for a transition to occur

Question 16

state

Answer 16

value/position of a system at a given point

Question 17

transition

Answer 17

change from one state to another

Question 18

structure chart

Answer 18

a structure chart is a graphical representation and modelling tool used to decompose a problem into smaller sub-tasks.
* module = one box
* conditional statement shown by a diamond
* parameters are shown by arrows pointing to the module receiving a parameter
* a filled-in arrow shows a boolean value
* repetition is shown by a curved arrow

Question 19

how to derive the pseudocode from a structure chart:

Answer 19

1. create an identifier table
2. declare constants & variables in pseudocode
3. create the pseudocode for each module. include the answers to all calculations.

Question 20

syntax error

Answer 20

an error in which a program statement does not follow the rules or grammar of a programming language

Question 21

logic error

Answer 21

error in the logic of a solution that causes it not to behave as intended

Question 22

run-time

Answer 22

error an error that causes program execution to freeze or crash due to invalid operations and extreme conditions. includes:
* arithmetic errors e.g. division by zero, negative roots
* overflow errors (variable holds a value too large
* stack overflow (no more space on a stack)
* library

Question 23

ways to minimise errors

Answer 23

• use extensively tried & tested library routines
• use modular programming → breaks down a problem into sub-tasks
• use good programming practice:
  1. sensible variable names
  2. white space
  3. indentation
  4. comments
• IDE features such as type-checking, auto-complete, debugging(variables, expressions and report window, single stepping, breakpoints), dynamic syntax checks, context-sensitive prompts

Question 24

stub testing

Answer 24

a stub is a simple module, which is written to replace each sub-routine. stub testing is used before the code is fully completed.

Question 25

integration testing

Answer 25

individually tested modules are joined to one program and tested to ensure modules interact correctly.

Question 26

black-box testing

Answer 26

compares actual results when a program is run to the expected results, and tests if programs meet specific requirements. test data is devised - normal boundary and extreme.

Question 27

white-box testing

Answer 27

tests every path and every line of code using suitable test data. tester views the code

Question 28

alpha testing

Answer 28

software is tested in-house by dedicated testers (programmers pretend to be users)

Question 29

acceptance testing

Answer 29

checks if the program performs as needed by customers before sign-off. acceptance criteria is set and end-user feedback is used to ensure the criteria is met.

Question 30

beta testing

Answer 30

final stage of testing before release. Users test it under realistic conditions, and feedback is obtained. problems are reported to the developer and are addressed + corrected.

Question 31

corrective maintenance

Answer 31

correcting identified errors, usually due to a logic or run-time error. earlier corrective maintenance may introduce errors

Question 32

adaptive maintenance

Answer 32

amending a program to enhance functionality or in response to specification changes. the program may perform a function it was not originally designed to do

Question 33

perfective maintenance

Answer 33

modifying a program to improve performance or maintainability - streamlining it. the program runs satisfactorily, but there is still room for improvement