chapter 4

Question 1

issues to be addressed when defining the problem

Answer 1

• requirements of the solution
• possible/cost-efficient??
• constraints vs resources available
• similar existing solutions
• team’s skill level

Question 2

performance requirements

Answer 2

list of requirements for the solution
- can become more specific set of specification under which the final product can be evaluated

Question 3

main aspects of defining the problem

Answer 3

1. understanding crucial details
2. inputs + outputs + processing
3. steps the solution must have
4. specifications of solution from client

Question 4

how to structure inputs and outputs

Answer 4

context diagram: level 0 data flow diagram which shows all external inputs + outputs

Question 5

how to structure steps of a solution

Answer 5

IPO diagrams: input –> processing –> output
- shows all inputs, processes, and outputs and decides nature of processing

Question 6

how to decide nature of processing

Answer 6

• consider a smaller version of the problem
• related/similar problems
• breaking down the problem
• brainstorming possibilities

Question 7

how to plan + design software solutions

Answer 7

• systematic breakdown
• think of nature of data + data structures
• design solution + algorithms

Question 8

abstraction

Answer 8

taking away/separating part of the problem/solution so that it can be considered in isolation
done through: breaking up solution into manageable modules

Question 9

why is abstraction good

Answer 9

• encourages reusable modules of code
• simplifies testing process

Question 10

refinement

Answer 10

the process of developing a hierarchy of sub-routines

Question 11

why is refinement good

Answer 11

• each high-level routine can access/call one or more low-level sub-routines
• code may not be reusable, but tailored to the specific problem

Question 12

system modelling tools

Answer 12

system model: representation of system; specifications to developers, structure + functionality

Question 13

system flowcharts

Answer 13

• demonstrates logic = flow of data through system
• high-level, provides overview of the whole system

Question 14

data flow diagrams

Answer 14

• describes the flow data takes through the system
• no timing of events indicated
• data stores: repositories for data, can be physical or digital
• external entities: = terminators, starting + ending points

Question 15

structure charts

Answer 15

• used to model hierarchy of subroutines + sequence in which they take place
• flow of data + data movements for clarity
• top-down design most popular, with decisions + repetitions included
• primary functions: top to bottom, left to right describing sequence

Question 16

data types

Answer 16

raw material, stored in binary

Question 17

binary

Answer 17

• base 2, 0 + 1
• yes or no, on or off
• based off transistors with only two states; on and off
• 8 bits = byte
• meaning dependant on context

Question 18

common predefined data types

Answer 18

• integer
• floating point
• string
• boolean
• date
• currency

Question 19

integer

Answer 19

• positive or negative
• WHOLE NUMBER!!
• no fractional values
• no. of bytes indicate range of integers which can be stored
• if a value outside the range is stored, will be mistype error
• calculations = fast + accurate

Question 20

floating point

Answer 20

• real numbers: fractional + large values
• the larger the number, the slower the processing + more storage needed
• single precision: 32 bits
• double precision: 64 bits
• possible inaccuracies + high processing demands

Question 21

string

Answer 21

• text data
• fixed length string: a string with a max. length
• dynamic length string: a string with no max. length
• unicode: universal code with everything

Question 22

boolean

Answer 22

• logical data
• true or false(yes or no)
• only two possible states
• 1 bool = 1 bit
• commonly used to signal whether section of code has been executed or not

Question 23

what is a subroutine

Answer 23

a set of statements that performs a single logical task

Question 24

what is a module

Answer 24

a group of subroutines that achieve a subtask

Question 25

what is a program

Answer 25

all the modules required to perform required task