Validating data

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When writing programs that take in data it is important to validate the data before processing it to prevent errors further down the line.

Validation check techniques

Note

The term constants refers to the limiting factors there is in a validation check

Range check

A range check checks if a number is within a range with a minimum and maximum number.

Length check

A length check totals up how many characters there are in a string and if the string is more or less than a certain length then it will fail.

Example

x = input("Enter string>")
if x >= 10:
	print("Fail")
else:
	print("Pass")

In this example if the string x is bigger or equal to 10 then it will fail.

Presence check

A presence check makes sure data is entered and will fail if there is no data in a field or variable.

Type check

A type check checks if a data type See here for common data types in programming is the correct data type.

Example

Asking for number.
- ABC
- True
+ 123
+ 583
- 1.1

Format check

A format check checks is a type of format entered is in the correct format.

Example

E.g: String entered must start four letters, have a _ and end in two numbers

- GH_54
- GHDA_2
- IENA_A
+ WHBU_12
+ OFBD_42

Check digit

A check did