Phoenix Network Forums

Hi everyone,

I have a problem in a site I am working in... I have to validate the username, because it can be only letters and numbers, started with a letter...
I tried to use preg_match(), but I don't know how to use regular expressions... It is hard to my brain assimilate all that codes, chars and magic things I have to put into my string...
I had read the manual, put can't undestand too much, and the little I undestanded was misunderstanded since not worked...

Any help?

Please note that I know no php ... I do know some Google though

Here's a site I found for "php regular expressions":
http://weblogtoolscollection.com/regex/regex.php

If you can use underscores, it would probably be something like:

Code: Select all

preg_match("/[a-z][\w]{3,14}/i", $YOURSTRING);

What that does is looks for a letter (case insensitive because the "i" modifier at the end), followed by 3-14 word characters (letters, numbers, and underscore).

If you do not allow the underscore (and I will be very angry, because I use one =P), you could try:

Code: Select all

preg_match("/[a-z][a-z\d]{3,14}/i", $YOURSTRING);

This does exactly the same, only it looks for a letter or a digit, but not an underscore.

Depending on the length of your username, you might have to change the values inside the braces though, this assumes a 4-15 character username.

Well .. the ad sure does lead you in the right direction.. lol.. (regex buddy!)

Regex buddy is great tool for learning and building regular expression.

There are a number of regular expression websites that can help

http://www.regular-expressions.info/

http://renschler.net/regexbuilder/

KODOS!!
http://kodos.sourceforge.net/comments.html

Regex for mixed-case usernames starting with a letter, the first is for unlimited length, the second is with length limited to 14 characters:

Code: Select all

^[A-Za-z][A-Za-z0-9]*$
^[A-Za-z][A-Za-z0-9]{1,13}$

Same as above, but with lowercase only:

Code: Select all

^[a-z][a-z0-9]*$
^[a-z][a-z0-9]{1,13}$