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Computer Science IGCSEPDF 91
142 pagesrevision 46930
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7.5 Checks
7.5.1 Validation Checks
● Their function is to check that the data entered is reasonable.
Validation
check
Function
Example
Range
The data is within a
set range
REPEAT
OUTPUT “Enter your marks”
INPUT Marks
UNTIL Marks > -1 AND Marks < 101
Length
The data is either an
exact number of
characters, or within a
range of number of
characters
REPEAT
OUTPUT “Enter your password”
INPUT Password
UNTIL LENGTH(Password) >= 8
The data conforms to
the required data type
Type
REPEAT
OUTPUT “Enter your age”
INPUT Age
UNTIL DIV(Age, 1) = Age
Prescence
Data has been
entered
REPEAT
OUTPUT “Enter your name”
INPUT Name
UNTIL Name <> “ ”
Format
The data conforms to
a specific format
REPEAT
OUTPUT “Enter your device code”
INPUT DeviceCode
UNTIL SUBSTRING(DeviceCode, 1, 3) = “XYX”
AND LENGTH(DeviceCode) = 6
Check digit
The final digit entered
in a code is correct
REPEAT
OUTPUT “Enter your device number”
INPUT DeviceNumber
OUTPUT “Enter your device code”
INPUT DeviceCode
UNTIL SUBSTRING(DeviceCode, 6, 1) = (2 *
DeviceNumber)