Topic: Detecting illegal characters - need help

[Corangar]

Here is the deal
i searched this forum and found a similar topic.
But the script didn't work for me and i dont wanna weak up the ghosts

Code: [Select]

if (!preg_match("/[a-z0-9]/i", $username){
   print "Username field has invalid characters!";
   exit;
}

Thats a code from "HuggieBear"
The thing is, script works for me in a way that it detects invalid characters but ONLY if all characters are invalid.
If i would insert as username "##$$" it would print "Username field has invalid characters!"
But if i insert "##C2" it would consider it as a valid character cuz of C and 2

With other words, i am searching for a script that would detect if it has ANY invalid character anywhere, no matter if valid characters were inserted.

Any help would be nice
thanks

[obsidian]

A slight alteration to the regexp will solve that. You need to tell the regexp engine to require all the characters to be within your ranges provided:

Code: [Select]

<?php
if (!preg_match("/^[a-z0-9]+\z/i", $username)) {
  // Your username contains invalid characters
}
?>

Or, you could simply match for any occurrence of a character not within your range (this may be better):

Code: [Select]

<?php
if (preg_match('|[^a-z0-9]|i', $username)) {
  // Your username contains invalid characters
}
?>


[rantsh]

Do you need to use preg? I guess ereg has is an easier function

I guess you could use something like

Code: [Select]

if(ereg("[a-z]|[A-Z]|[0-9]";$var)) {
  //valid
} else {
  //invalid
}

That'll look for any alpha-num char and return true if present.

Hope I was helpful, and btw, I guess this topic goes on the Regex forum...

Regards,

Roderick

[effigy]

Do you need to use preg?...I guess you could use something like ...[a-z]|[A-Z]|[0-9]...

Per the docs:

Note:  preg_match(), which uses a Perl-compatible regular expression syntax, is often a faster alternative to ereg().

Also, never alternate like that--combine the class: [A-Za-z0-9]

[Corangar]

Code: [Select]

<?php
if (!preg_match("/^[a-z0-9]+\z/i", $username)) {
  // Your username contains invalid characters
}
?>
This works perfectly, thank you all