Simple Username Creation Validation with PHP
When I create login areas (mostly intranets) for small websites, I'm always asked by the customer to keep
usernames to letters and numbers. That means no email addresses as usernames
and special characters like "_", "-", and ".". This, in my customer's mind,
keeps the login easy for their users and limits the number of support calls
they will receive. While I don't recommend disallowing common username
characters like the ones cited above, I do understand their need for simplicity.
Here's how, using PHP, I validate that a username is only letters and numbers.
The PHP
function validate_username($input,$pattern = '[^A-Za-z0-9]')
{
return !ereg($pattern,$input);
}
It's as easy as that. I don't go as far as using this for passwords, but you could if you wanted to. I'll also mention that if I want to allow non-alphanumeric characters, I just need to change the function's pattern. Easy enough!
![fetch API]()
One of the worst kept secrets about AJAX on the web is that the underlying API for it, XMLHttpRequest
, wasn't really made for what we've been using it for. We've done well to create elegant APIs around XHR but we know we can do better. Our effort to...
![Welcome to My New Office]()
My first professional web development was at a small print shop where I sat in a windowless cubical all day. I suffered that boxed in environment for almost five years before I was able to find a remote job where I worked from home. The first...
![MooTools FontChecker Plugin]()
There's a very interesting piece of code on Google Code called FontAvailable which does a jQuery-based JavaScript check on a string to check whether or not your system has a specific font based upon its output width. I've ported this functionality to MooTools.
The MooTools...
![Retrieve Google Analytics Visits and PageViews with PHP]()
Google Analytics is an outstanding website analytics tool that gives you way more information about your website than you probably need. Better to get more than you want than not enough, right? Anyways I check my website statistics more often than I should and...
I like the approach — instead of matching a word boundary e.g. ^[a-zA-z0-9]*$ you match the first invalid character. I wonder what the speed difference is…
BTW, you can use [^\w\d] insead ;) It’s lazier
My bad. You cant use \w since it matches _ as well. On the other hand \w handles \d, so if you are looking for something quick for chars, digits and _ — you can use \w.
You could also use PHP’s ctype_alnum to match only alphanumeric characters
which matches (ever so slightly) faster than its equivalent regular expression,
and still retain future flexibility by using something like:
Of course the speed difference is on the order of nanoseconds,
but it is faster nonetheless.
A better method name would be useful. ;)
@Jeff: Ooops. I have this function within a class. I actually use it like this:
I simply didn’t rename it for the blog. I’ll do that quick!
A word of warning,
ereg
is being removed in PHP6 because of the more powerful and usually fasterpreg
. Altering your code to work withpregs
is easy and safer should the server you’re on upgrade to PHP6 sometime in the future:ereg will be deprecated in php 5.3 and removed in 6, use preg instead
ereg is not available in php 5.3.0
any alternative for this ?
I’m rather new to regexp, and am just trying to get something exactly like this to work, but it just isn’t. I got annoyed, and then simplified as much as possible to this:
and it isn’t responding anything except 0, no matter what I try.
Oops sorry. Anyways, it’s just a text input that posts to itself, and it deals with the post by doing
The Best way I recommend is this :-