Regular Expression Matching - quick question

AliasZero

Hey there, i'm trying to write some code to validate a username.

The specifics for the username are:
- Alphanumeric
- Can't begin with Mod or Admin

So far, i have

/^{(Mod|Admin)[a-zA-Z0-9]+$/}
(pcre regex - preg_match)

However this matches when the username DOES start with Mod or Admin.

How would I reverse this, so if it starts with Mod or Admin it doesn't match?

Thanks

jpmoriarty

why not just split it up?

do:

if((substr($username,0,3)!="Mod" || substr($username,0,4)!="Admin")) && ...preg matching...

LordShryku

The preg matching can also be accomplished with [man]ctype-alnum[/man].

Moonglobe

Originally posted by jpmoriarty
why not just split it up?

do:
if((substr($username,0,3)!="Mod" || substr($username,0,4)!="Admin")) && ...preg matching...
[/B]

um.. admin is 5 letters, not four.

Weedpacket

((substr($username,0,3)!="Mod" || substr($username,0,5)!="Admin"))

This test could only fail if $username starts with both "Mod" and "Admin" 🙂. Change the || to &&. That said, this would be faster (and probably easier to maintain) than trying to do the whole deal with a single regexp.

jpmoriarty

But of course weedpacket. Getting my negatives confused.

And don't be so picky moonglobe - i was trying to help, and i think everyone got the idea

AliasZero

Thanks guys, the regex i needed in the end were:

/^{(?!ModAdmin)[a-zA-Z0-9]$/}