regex for matching two or more numbers, then one 'x', then two or more numbers

Question

I'm having trouble constructing this regex. I need a strpos or a preg_match that will match the following pattern: 00x00. where the '0's are any number(s), and x is upper or lowercase, then a period.

I know I can do \d for numbers, but don't know how to specify two or more numbers. I know I can do [xX] for either upper or lowercase 'x', and I'm lost on the period.

I've tried this:

preg_match ( '/\\d[xX]\\d\./', $string )

but that isn't working.

I'd prefer to do it with a strpos, but either is fine.

EDIT - The period is optional; it's just added security. But I'm not sure if it's possible to match it not knowing how many numbers are between the 'x' and the period.

Answer 1

Something like so: \d{2,}[Xx]\d{2,}\. will match two or more digits, an x (ignoring case) and two more digits and a period.

If that is all you want to match, I would recommend adding the anchor tags: ^\d{2,}[Xx]\d{2,}\.$. This will instruct the regex engine to match exactly that.

So in short, this \d{2,}[Xx]\d{2,}\. will match foo bar 000X00 foo bar but this: `^\d{2,}[Xx]\d{2,}\.$ will match only 000X00 and nothing else (so it will fail for my previous example).