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AW2 - Coggle Diagram
AW2
Data Types
Char
a,F,3,$,£,#
String
abc, hello world
Real
4.2,27.4,5.63
Boolean
true or false
Integar
Whole Number
4,27,65535
Pseudocode example
Assignment
Selection
Iteration
Totalling/counting a variable
Verification and Verification
Validation
Validation is an automatic computer check to ensure that the data entered is sensible and reasonable. It does not check the accuracy of data
Types of validation
Length Check
Checks the data isn't too short or too long
A password which needs to be six letters long
Lookup Table
Looks up acceptable values in a table
These are only seven possible days of the week
Format Check
Checks the data is in the right format
A National Insurance Number
Presence Check
Checks that data has been entered into a field
In most databases a key field cannot be left blank
Check Digit
The last one or two digits in a code are used to check the other digits are correct
Bar code readers in supermarkets use check digits
Range Check
Checks that a value falls within the specified range
Number of hours worked must be less than 50 and more than 0
Verification
Verification is the process of making sure data is copied over from one medium to another correctly.
Methods of Verification
Double Entry
Entering the data twice and comparing the two copies. This effectively doubles the workload, and as most people are paid by the hour, it costs more too.
Proofreading data
This method involves someone checking the data entered against the original document. This is also time-consuming and costly.