Question

I need to validate a string that contains a number (the number can’t be 0 or have zeros at the begining) or a number followed by a single characters in the range a-z or A-Z. So, these are all valid

2, 12, 1, 324534A, 2Y, 934d

but these are all invalid

000R, 0, 0D, D3, 23432dddd, 234Q343.

Can someone show me the correct regex expression for this?

Answer 1

This should match.

^[1-9]\d*[a-zA-Z]?$

Breakdown:

^           - Match start of string
[1-9]       - Followed by one digit (1-9), no 0
\d*         - Followed by any number of digits (can contain digits from 
              other cultures). If you want to constain use [0-9] instead of \d
[a-zA-Z]?   - Followed by either one character or none
$           - Followed by end of string