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!
![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...
![Creating Scrolling Parallax Effects with CSS]()
Introduction
For quite a long time now websites with the so called "parallax" effect have been really popular.
In case you have not heard of this effect, it basically includes different layers of images that are moving in different directions or with different speed. This leads to a...
![Hot Effect: MooTools Drag Opacity]()
As you should already know, the best visual features of a website are usually held within the most subtle of details. One simple trick that usually makes a big different is the use of opacity and fading. Another awesome MooTools functionality is...
![Flexbox Equal Height Columns]()
Flexbox was supposed to be the pot of gold at the long, long rainbow of insufficient CSS layout techniques. And the only disappointment I've experienced with flexbox is that browser vendors took so long to implement it. I can't also claim to have pushed flexbox's limits, but...
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:
function username($input, $pattern = false) { return ($pattern) ? !ereg($pattern, $input) : ctype_alnum($input); }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:
if($valid->username($input)) { // move on... }I simply didn’t rename it for the blog. I’ll do that quick!
A word of warning,
eregis being removed in PHP6 because of the more powerful and usually fasterpreg. Altering your code to work withpregsis easy and safer should the server you’re on upgrade to PHP6 sometime in the future:function validate_username($input, $pattern = '/[^A-Za-z0-9]/') { return !preg_match($pattern, $input); }ereg will be deprecated in php 5.3 and removed in 6, use preg instead
ereg is not available in php 5.3.0
any alternative for this ?
I’m rather new to regexp, and am just trying to get something exactly like this to work, but it just isn’t. I got annoyed, and then simplified as much as possible to this:
and it isn’t responding anything except 0, no matter what I try.
Oops sorry. Anyways, it’s just a text input that posts to itself, and it deals with the post by doing
if(!is_null($_POST["f"])){ $input=$_POST["f"]; $pattern = '[^A-Za-z0-9]'; $a=preg_match($pattern,$input); echo $a; }The Best way I recommend is this :-
$str = ""; function validate_username($str) { $allowed = array(".", "-", "_"); // you can add here more value, you want to allow. if(ctype_alnum(str_replace($allowed, '', $str ))) { return $str; } else { $str = "Invalid Username"; return $str; } }