Rejecting illegal characters for Asian char sets

@HaganeNoKokoroApr 13.2005 — #It would be better to do this in your php code; you should [b][u]always[/u][/b] have server-side validation of form input. In PHP, you would use preg_match to find out if there were any illegal characters, and return an error. For example, to find out if there are any characters aside from a-z, A-Z, 0-9, and _, you would use something like

<i>
 </i>...
 
 $input=$_POST['forminput'];
 $pattern='/^[w]/';
 if(preg_match($pattern, $input)&gt;0) {
 //do something to tell the user they must only input valid characters
 } else {
 //input OK
 }

I am not very experienced at PHP, you may want to look over www.php.net for more information on how to use the preg functions.

You can still have client-side validation as well. The way to do this is similar

&lt;script type="text/javascript"&gt;
 function check(elem) {
 if(/^[w]/.test(elem.value)) {
 alert("You have entered invalid characters.");
 elem.focus();
 }
 }
 &lt;/script&gt;
 
 ...
 
 &lt;input name="input1" type="text" onchange="check(this)"&gt;
 
 ...

In some browsers, the onchange event will fire as the user types, in others it will fire when the input loses focus. You could use key events, but they are not as well supported and will not catch changes due to pasting text.

Also note this type of client-side checking could get very irritating because it will not let the user leave until they remove all invalid characters, and is easily bypassed (intentionally or unintentionally) by disabling javascript, so the server-side is far more important.

@SpectreReturnsApr 13.2005 — #In php, just check if the ord() of a certain character is less than 255.

@ozconnectauthorApr 13.2005 — #My own experience is that server side validation is too late. Yes it would stop the bad characters corrupting my data base but I want to fix it at the source.

@SpectreReturnsApr 13.2005 — #However, it's easy enough to bypass javascript security, so you're going to need to do it serverside if you want it to be secure.

Rejecting illegal characters for Asian char sets

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Rejecting illegal characters for Asian char sets

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