2.2 problem solving and programming Flashcards
2.2.1 programming techniques
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what are the three programming constructs
-sequence
-branching
-iteration
sequence
Code is executed line-by-line, from top to bottom
branching
A certain block of code is run if a specific condition is met, using IF
statements
iteration
A block of code is executed a certain number of times or while a condition is met. Iteration uses FOR, WHILE or REPEAT UNTIL loops
local variables
Local variables have limited scope which means that they can only be accessed
within the block of code in which they were defined
global variables
, can be accessed across the whole program
two advantages of using local variables over global variables
-less memory is used
-self-contained so unaffected by code outside subroutine
2.2.2 software development
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what are the common stages of software development life cycles (SDLC’s)
analysis, design, development, testing, implementation, evaluation and maintenance
what are the different types of testing
-alpha testing
-beta testing
-white-box testing
-black-box testing
-alpha testing
-beta testing
both carried out when software is nearly ready for release
-Alpha testing is carried out in-house by the software development teams within the company. Bugs are pinpointed
and fixed.
-Beta testing is carried out by end-users after alpha testing has been completed. Feedback from users is used to inform the
next stage of development.
-white-box testing
-black-box testing
-involves testing the algorithms in the code and making sure all parts of those algorithms function as intended. Unlike black-box testing, it also checks the overall efficiency of the code
-checks whether an input produces the expected output. without checking how it has been coded
-waterfall lifecycle
-advantages
The waterfall lifecycle has a series of stages that each have to be completed before moving to the next one
ADV: straightforward to manage, clear structure, clearly documented
what is TELOS
a method of analysis used by designers to evaluate the feasibility of a project. It considers technical, economic, legal and operational aspects of the project, as well as scheduling
drawbacks of waterfall method
If a change needs to be made within a project being developed using the waterfall model,
programmers must revisit all levels between the current stage and the stage at which a
change needs to be made. This makes the model inflexible and so unsuitable to projects
with changing requirements. This also means that users have little input as they are only
involved at the very beginning and end of the waterfall lifecycle, during the analysis and
evaluation stage.
agile methodologies
This refers to a collection of
methodologies which aim to
improve the flexibility of
software development and
adapt to changes in user
requirements faster
-extreme programming
-disadvantages
an agile software development framework that aims to produce higher quality software and higher quality of life for the development team. code is written by one person and critiqued by the other so is improved as it is written
DIS: High cost due to two people working on one project, teamwork and good communication is essential, End-user must be present throughout the duration of the project
spiral model
a software development methodology that combines aspects of both iterative (agile) and sequential (waterfall) processes.
Spiral programming methodologies are suited to large risk-intensive projects with a high budget
what types of projects are rapid application development (RAD) programming methodologies suited for
projects where high usability is required and user requirements may not be clear from the outset or are continually changing. Suited to projects of a small to medium size with a relatively low budget and short time-frame
the three test strategies
● Normal -Data within the range of the data type considered as valid.
● Boundary -Data that falls at either of the ends of the valid data range.
● Erroneous -Data that falls outside of the valid data range
dry-run
another type of test stratergy when programmers
manually work through the code. Take each line at a time and write out the current state of each variable in a trace table.If an unexpected result is produced, the cause of this can be traced and fixed. The downside to dry-runs is that they cannot pick up on run-time/execution errors.
