validation Getting started with validation Validating an age against a range

Example

Let's take the Range is from 18 to 80.

So, to validate,

We should check that the age is a positive integer.

Then check it should be greater than or equal to 18 and less than or equal to 80.

The test to check whether it is a number or not can be performed by a simple regular expression like

^[0-9]+$

Or even simpler

^\d+$ 

Then we can check it with range as

if age>=18 && age <=80 return true
else return false