Chapter 7 Flashcards
What are the 4 stages of software development lifecycle
1) Analysis
2) Design
3) Coding
4) testing
Analysis
Part of the program development life cycle
Uses abstraction and decompositions tools to identify exactly what is required from the program
Abstraction
Keeps the key elements required for the solution to the problem and discards any unnecessary details and information that is not required.
Decomposition
breaks down a complex problem into smaller parts which can then be divided into into even smaller parts that can be solved easily.
Design
The program specification from the analysis stage is used to show how the program should be developed.
Structure diagrams , flowcharts, pseudo code
Coding
The program is developed/ written.
Iterative testing test are repeated until the module performs as required.
Testing
Testing program code using test data to make sure it meets the requirements.
What is a computer system made up of
Software , data , hardware , communications and people
Computer sub systems
Each computer system can be divided up into a set of sub systems. Each sub system can be further divided inti sub systems and so in until each sub system just performs a single action
Computer systems sizes
Can be very large , very small or any size in between
Computer systems sizes
Can be very large , very small or any size in between
Top down design
The decomposition of a computer system into a set of sub systems then breaking each sub system down into smaller sub systems until each sub system just performs a single action.
Decomposition
Breaking a complex problem down into smaller more manage parts
Advantages of problem decomposition
Makes problems easier to solve
Different people can work on different parts of a problem at the same time, reducing development time.
Program components developed in one program can easily be used in other programs
Inputs
The data used by the system that needs to be entered while the system is active
Processes
The tasks that need to be performed using the input data and any other previously stored data
Outputs
Information that needs to be displayed or printed for the users of the system
Storage
Data that needs to be stored in files on an appropriate medium for use in the future
Structure diagrams
A hierarchical way of showing how a computer system solution can be divided into sub systems with each level giving a more detailed breakdown.
Flowcharts
An Show the steps required to complete a task and the order that they are performed.
Terminator flow charts
Are used at the beginning and end of each flowcharts.
Start stop
Rectangle with curved edges
Structure diagrams
A method of designing a solution to a problem
Produced using a methid known as step wise refinement
Break a problem down into smaller sub problems using decomposition
Some areas of the program will need to be broken down more than others
Lowest level nodes should achieve ine task and therefore be coded as a single module or sub program
Pseudo code
Is an alternative text based way of representing the sequence of steps in an algorithm
Simplified form of programming code
Without worrying about the actual rules and syntax of a particular language
Process
Square
Where something is happening like a calculation
Decision
Diamond
Ask a question
Input and output
To display input or output parallelogram
Subroutine
Rectangle with 2 lines
Pseudo code
+
-
*
/
( )
<-
Add
Subtract
Multiply
Divide
Raise to the power
Group
Has the value
