regex: to tough for me

[ednark]

i'm having a hard time with this regular expression... maybe this comes easy to one of you out there:

i need to determine two things. hopefully in one go:

1) if i have a total of 10 digits delimited by 3 nonconsecutive '-':

ie something like this ok:

0-00000-00-00

but not like this:

0--00000000-00

i don't know how to make it match up to 10 digits with 3 '-'s somewhere in between them.. 😕

2) i need to remove all 'X's but leave one if it is the last character in the string. 😕

i could just do this in several passes i now that... however... im sure there has to be a way to do it one one go. maybe this will be an interesting puzzle for one of you regex gurus out there

[Weedpacket]

You don't say whether a hyphen could start or end the string 🙂

A PCRE regexp for the job is

/(?<![-\d])(?=[-\d]{13})(?![-\d]{14})(\d*-\d+-\d+-\d*)/

The first bracketed section makes sure we don't have any hyphens or digits immediately to our left (it pins searches to the start of digit/hyphen groups and so prevents matching things like 0000000000000-0-00-0000).

The second makes sure there are at least 13 digits and hyphens immediately to our right (to make sure of course that it's long enough)

The third makes sure there aren't too many digits and hyphens.

The fourth bracketed expression is the match itself and is pretty self-explanatory as regexps go. If you dont' want hyphens at the start or end, change the appropriate * to a +.

Oh, and the second one is a P.O.P.

$string = preg_replace('/X(?=.)/','',$string)