How can I validate the range 1-99 using a regex?

Question

Hi,

I need to validate some user input, to ensure a number entered is in the range of 1-99 inclusive. These must be whole (Integer) values

Preceeding 0 is permitted, but optional

Valid values

1. 1
2. 01
3. 10
4. 99
5. 09

Invalid values

1. 0
2. 007
3. 100
4. 10.5
5. 010

So far I have the following regex that I've worked out : ^0?([1-9][0-9])$

This allows an optional 0 at the beginning, but isn't 100% correct as 1 is not deemed as valid

Any improvements/suggestions?

Answer 1

Here you go:

^(\d?[1-9]|[1-9]0)$

Meaning that you allow either of

1. 1 to 9 or 01 to 09, 11 to 19, 21 to 29, ..., 91 to 99
2. 10, 20, ..., 90

Answer 2

Off the top of my head (not validated)

^(0?[1-9]|[1-9][0-9])$

Answer 3

^(([0-9][1-9])|([1-9][0-9])|[1-9])$

should work

Answer 4

String d = "11"

if (d.length() <= 2 && d.length() >=1) {
try {
 Integer i = Integer.valueOf(d);
   return i <= 99 && i >= 0
 }
catch (NumberFormatException e)
{
 return false;
}
}

Answer 5

^[0-9]{1,2}$ should work too (it'll will match 00 too, hope it's a valid match).

Answer 6

Why is regex a requirement? It is not ideal for numeric range calculations.

Apache commons has IntegerValidator with the following:

isInRange(value, 1, 99)

In addition, if you're using Spring, Struts, Wicket, Hibernate, etc., you already have access to a range validator. Don't reinvent the wheel with Regular Expressions.

Answer 7

I might miss the point, but why not use ^\d?\d$ ?