Hi, I'm trying to check the format of the string with preg_match(). It has to accept only the
(zero or more of ,.* )(exactly 9 or 5 digit number)(1 or more of ,.* )(postive integer <= 4digits)(zero or more of ,.* ) format of strings.
Here, is what I tried:

It is working with these numbers:

, *123456789, *51*, => true (exactly 9)
, .*12345, *51*, => true (exactly 5)
, .*123, *51*, => false (less than 5)
This is where I failed:

, .*1234567891011, *51*, => true (greater than 9), It is just considering the first 9 digits & ignoring others & returing true, but I should actually get false

, .*123456, *51*, => true (in between 5 &9), same here, considering first 5 digits & returning true.
Thanks for any help!

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Exact number of digits always trips me up, but I think you can do it with negative look-behind ?<! and negative look-ahead ?!:


Hey, I forgot to mention. I've tried that too. It is working when I simply use it for a number.
For eg: (?<!\d)(\d{5}|\d{9})(?!\d) works fine for 12345 or 123456789.
But, it isn't working fine when I consider the complete example.
((\s|\*|,|\.)*)(?<!\d)(\d{5}|\d{9})(?!\d)((\s|\*|,|\.)*) should match *., 12345.,.* and ,.123456789,.* but it isn't matching anything at all. Any Idea why?

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Don't you need to isolate the digit part with the neg looks by placing () around the whole lot?

Maybe this is overkill, but it may work with your use-cases - not tested thoroughly:

$pattern = "/[,\. \*]*((?<!\d)(\d{5}|\d{9})(?!\d))[,\. \*]+(\d{1,4})(?!\d)[,\. \*]*/";