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

Question

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 opt

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