Alphanumeric and more

Question

So I am designing a registration page and checking the username is alphanumeric.

         else if(!eregi("^([0-9a-z])+$", $subuser)){
        $form->setError($field, "* Username not alphanumeric");

I use that to do so. Is there any way I can get that to include underscores (_), dash (-), and spaces? Thanks

Answer 1

You can use:

else if(!eregi("^([0-9a-z_ -])+$", $subuser)){

You just need to add an underscore(_), a hyphen (-) and a space( ) to the char class. Of the three only hyphen has special meaning in the char class but only if its surrounded on both sides by char. So to avoid this you can include it at the beginning or at the end. You can also include it in the middle and escape it.

So the following are also valid:

else if(!eregi("^([-0-9a-z_ ])+$", $subuser)){
else if(!eregi("^([0-9a-z_\- ])+$", $subuser)){

Answer 2

You can use like this

if(!eregi("^([0-9a-z-_ ])+$", $subuser))

u can add as many special character in this bracket [0-9a-z-_ ] but be sure coz some need to be escaped by (slash)

Answer 3

it is better to learn using preg_match syntax because that is a standard regular expression check.

with that it should be like this:

$bValid = preg_match("/^[\w\d-_]*$/", $sUsername);

for feather reading about regular expression check read http://www.php.net/manual/en/intro.pcre.php

and for short comparison between preg_match and ereg see http://answers.yahoo.com/question/index?qid=20080327071915AAO0O2w