Syntax question

[phpknight]

Hi,

 

I am new the regex part of PHP and am trying to get a simple regex working with a set of four to six alphanumeric characters.  This works:

 

^([^b]{4,6}) -- 5-6 characters--not b

 

but once I do this:

 

^([:alnum:]{4,6})

 

it does not work.  I've also tried doubling the brackets around alnum.  I know I am missing something simple.  I would appreciate some help.

[MadTechie]

i think you want this

 

$data = "test";
if (preg_match('/^[a-z0-9]{4,6}$/i', $data)) {
# Successful match
} else {
# Match attempt failed
}

 

or

$data = "test";
if (eregi('^[a-z0-9]{4,6}$', $data)) {
# Successful match
} else {
# Match attempt failed
}

 

 

$data = "test"; //works
$data = "testing"; //fails
$data = "tst"; //fails

[phpknight]

So, is [:alnum:] not allowed, or is it the $ at the end that I am missing?

 

What is the difference between the one with /i and the one without it?

[MadTechie]

persaonlly i keep away from [:alnum:] personal choice..

 

The ^ means starts with and the $ means ends with so the whole string is from 4 to 6 chars

the /i or eregi, means case insensitive.. so only a-z needed not a-zA-z.

 

make sense ?

[phpknight]

Yes, that makes sense.  I'll be sure to let you know if this helps me out.  In fact, I think you answered another question of mine today, to thanks!

 

Also, if you do know the alnum stuff, please post that as well.

[MadTechie]

a [:alnum:] version

<?php
$data = "test";
if (eregi('^[[:alnum:]]{4,6}$', $data)) {
# Successful match
} else {
# Match attempt failed
}
?> 

[phpknight]

Weird.  I am using Regex Coach along with .htaccess to test these.  If I do anything like alnum, it fails.  But if I do this:

 

^[a-zA-Z0-9]{4,6}

 

it works.  What is the deal?

[effigy]

.htaccess means mod_rewrite, which uses PCRE. PCRE does not support that syntax.

[phpknight]

Are you serious?  I am reading the definitive guide to mod rewrite, and this is in there.  I guess that would explain it, though!

 

Can you give me a definitive link to what works in PCRE?  ???

[MadTechie]

~cougths~

 

http://www.pcre.org/

http://uk2.php.net/pcre

[phpknight]

If you search for POSIX CHARACTER CLASSES on this page: http://www.pcre.org/pcre.txt it has alnum!  What gives?

[MadTechie]

can you post the mod_rewrite

[effigy]

From the mod_rewrite docs:

 

Pattern is a perl compatible regular expression.

For more information about regular expressions, have a look at the perl regular expression manpage ("perldoc perlre").

 

...which points directly to Perl's regular expressions--not a "compatible" version. There is either a mix-up in terminology, or a more flexible definition of compatible involved.

[phpknight]

Okay.  Somebody just told me that apache 1.3.37 does not support this notation, only Apache 2.  Does that sound right to anybody?