validating alpha-numeric password

[bcamp1973]

i want to force users to create passwords that are alpha-numeric only.  however, i'm not quite sure how to validate their entry.  i'm guessing preg_replace() is an option, but is it the best one?  Is there a built in PHP function for this? I haven't been able to find it at php.net if there is :(

[hitman6003]

You can use a js regular expression for this:

[code]function checkpw(pass) {
var m = /^[0-9a-zA-z]$/;
if (!pass.match(m)) {
alert("Please use only numbers and letters for your password.");
return false;
} else {
return true;
}
}[/code]

call is by using either a onsubmit on the form, or on blur on the form field:

[code]<input type="password" name="password" size="10" onblur="checkpass(this);">[/code]

[ronverdonk]

Sorry for the intrusion, but isn't this a PHP forum?

[Drumminxx]

another problem with that is if the user has javascript turned off...

here's an example using eregi which is case insensitive

[code]<?
$s = "Ssertfrt633";

if (eregi('^[[:alnum:]]{2,}$',$s)) {
echo 'ok';
}else{
echo 'bad';
}

?>[/code]