What's a good maxlength for an alphanumeric username?

[txtsd]

I like periods/hyphens more than underscores. Idk why.

BECAUSE PERIODS!

I'm going to send you a PM as I have some ideas, but I do believe you should allow hyphens. -

4 hours later, still waiting for OP to deliver.

[Zeus]

BECAUSE PERIODS!





4 hours later, still waiting for OP to deliver.

Sorry man, still working on previous project. Will be mailing you now.

[txtsd]

@(you need an account to see links) @(you need an account to see links) Are you guys advocating multiple hyphens or a single hyphen?
Because people might make silly usernames like X------D and B-------D
I-H-I looks like a cool fighter drone though, so idk.

[Zeus]

@(you need an account to see links) @(you need an account to see links) Are you guys advocating multiple hyphens or a single hyphen?
Because people might make silly usernames like X------D and B-------D
I-H-I looks like a cool fighter drone though, so idk.

My original proposal was multiple hyphens that can't be in sequential order. But that seems like a bit much so possibly just a single hyphen.

[Zachafer]

Personally, I'm a fan of allowing underscores (or spaces) in the username.

Also, you could use something like this for your username regex (specifies length 3-24):

$rgx = '/^([a-z][a-z0-9]{2,23})$/i'; 

My original proposal was multiple hyphens that can't be in sequential order. But that seems like a bit much so possibly just a single hyphen.

function validateUsername($test)
{
    $rgx = '/^([a-z][a-z0-9-]{2,23})$/i';
    return preg_match($rgx, $test) && strpos($test, '--') === false;
} 

Or the all in one regex (wow)

• Case insensitive
• Username length 3-24
• Username starts with a-z
• Username can contain hyphens but cannot contain repeating hyphens
• Username allows character [a-z0-9-]

$rgx = '/^[a-z](?:[a-zA-Z0-9]|(-)(?!\1)){2,23}$/i'; 

[Roslyn]

My original proposal was multiple hyphens that can't be in sequential order. But that seems like a bit much so possibly just a single hyphen.

This sounds right. (:

[txtsd]

function validateUsername($test)
{
    $rgx = '/^([a-z][a-z0-9-]{2,23})$/i';
    return preg_match($rgx, $test) && strpos($test, '--') === false;
} 

Or the all in one regex (wow)

• Case insensitive
• Username length 3-24
• Username starts with a-z
• Username can contain hyphens but cannot contain repeating hyphens
• Username allows character [a-z0-9-]

$rgx = '/^[a-z](?:[a-zA-Z0-9]|(-)(?!\1)){2,23}$/i'; 

Holy wowza! I've never used a negative lookahead assertion before.
I don't use php, but thanks. The regex will do just fine.

And thanks everyone for your inputs!