Question

I’m looking for a regex that will match against: X_X

Where X is always a number great than zero and there must be an underscore character in between the two numbers.

Thanks.

EDIT: When I run

$pattern = “[1-9]_[1-9]”; if(
preg_match($pattern, $key) ) return
TRUE;

I get Warnings:

Message: preg_match()
[function.preg-match]: Unknown
modifier ‘_’

Answer 1

The following should do what you want:

preg_match("/[1-9]\d*_[1-9]\d*/", $key)

Note that this will work for numbers with more than one digit as well, if X in your example is only a single digit number then you can remove the \d*.