2.1 Algorithm Design Flashcards
Describe the purpose of validation
To test whether the data entered is reasonable/sensible.
State 5 types of validation check
Range check
Type check
Length check
Presence Check
Character check
+ Format check
+ Look up check
Describe a length check and give an example
Checks whether the data entered is within a certain number of characters
e.g. Passwords often have a minimum and maximum number of characters
Describe a range check and give an example
Checks whether the values entered are within a certain range
e.g. exam percentage must be between 0 and 100
Describe a presence check and give an example
Checks that some data has been entered (not left blank)
e.g. you must enter a username when setting up an account
Describe a type check and give an example
Check that the correct type of data has been entered
e.g. you must enter an integer when inputting an age
Describe a format check and give an example
Check that an appropriate format of letters and numbers has been used
e.g. Date must be in the format DD/MM/YYYY
Describe a character check and give an example
Checks that the input contains (or does not contain) specific characters
e.g. Passwords must contain uppercase, lowercase characters and digits
Describe the purpose of verification
To check that the data input is the same as the original source (intended input)
Describe 2 types of verification
Double Entry - Expects data to be entered twice and compares both entries to check if they are the same.
Visual Check - Data is entered once and then visually compared against the original (or entered value)
State 4 different types of test data
Normal (valid)
Abnormal (invalid)
Extreme
Boundary
Describe normal/valid test data
Data that should be accepted and has known outcomes
Describe abnormal/invalid test data
Data that should be rejected and produce error messages
Describe extreme test data
The largest and smallest values that would be accepted
Describe boundary test data
Is used to establish where the largest and smallest values occur.
At each boundary 2 values are required: one valid and one invalid
A user is asked to enter a valid percentage. It must be a positive whole number between 0 and 100 inclusive.
State 4 different types of test data and for each one give an example of one piece of appropriate data along with a reason
Normal … 23 … the value is within normal range and should be accepted
Abnormal … 3.3 … the value is an invalid data type and should be rejected
Extreme … 100 … the value is the largest value that should be accepted
Boundary … 101 … tests the invalid value at the highest boundary and should be rejected
What is an algorithm?
A set of step-by-step instructions to solve a problem of complete a task
It is independent of any programming language
Can be expressed using pseudocode or a flowchart
What are the names and shapes of the 5 flowchart symbols you need to know?
Convert to a flowchart
Convert to a flowchart
Convert to a flowchart
Convert to a flowchart
Convert to a flowchart
Convert to a flowchart
Convert to a flowchart
Convert to a flowchart
What is a structure chart?
- A modelling tool used to show the hierarchy of a system/program
- A graphical representation to show how a system is broken into subsystems
What are library routines?
A collection of standard programs/routines availaible for immediate use
What is a subroutine?
- A self-contained piece of code that that is given a name and can called from within a program
- 2 types of subroutines
- A function - always returns a value
- A procedure - may or may not return a value
What is a procedure?
A subroutine that does not have to return a value
What is a function?
A subroutine that always returns a value
Describe the use of a subroutine in a program
- It is a block of code within a program that can be called when needed
- It breaks up the program to make it easier to read and understand
- It can be reused by another program
What is a library routine?
- A standard subroutine that is available for immediate use
- It can be called from many programs
- It is used often and makes programs easier/faster to write as the code is already written
- They make testing easier as they have already been used and debugged
What is top down design?
Breaks down a system into successively smaller pieces/sub systems
What are the benefits of top down design?
- allows several programmers to work at the same time on the software
- Development time is faster
- can test each subsystem independently
- Easier to debug
