valid name in portuguese

[delfa]

Ok, this should be simple but i sumply can´t do it!

Look, i want to validade a name submitted in a form (just to accent alphanumeric characters).

In english we use this:

   if (eregi('[^a-zA-Z0-9 ]', $name)) echo 'Invalid!';

but for portuguese where we can have names like João it doesn´t work because if the 'ã'

HELP!!!!!!!

[Mordecai]

Here are the codes, appearance, and name of the vowels:
0224 à Latin Small Letter A With Grave
0225 á Latin Small Letter A With Acute
0226 â Latin Small Letter A With Circumflex
0227 ã Latin Small Letter A With Tilde
0228 ä Latin Small Letter A With Diaeresis
0229 å Latin Small Letter A With Ring Above
0232 è Latin Small Letter E With Grave
0233 é Latin Small Letter E With Acute
0234 ê Latin Small Letter E With Circumflex
0235 ë Latin Small Letter E With Diaeresis
0236 ì Latin Small Letter I With Grave
0237 í Latin Small Letter I With Acute
0238 î Latin Small Letter I With Circumflex
0239 ï Latin Small Letter I With Diaeresis
0242 ò Latin Small Letter O With Grave
0243 ó Latin Small Letter O With Acute
0244 ô Latin Small Letter O With Circumflex
0245 õ Latin Small Letter O With Tilde
0246 ö Latin Small Letter O With Diaeresis

These can be achieved by using chr(ascii code):
chr(0224) = à

I'm not very good with regular expressions, so I'm not sure how (or if) you can use these in that case. However, it is good information to know if you wish to write a workaround.

[laserlight]

This provides a possible solution, though I suspect that it may not always work:
http://www.php.net/manual/en/function.ctype-alnum.php

I tested with what amounts to:

<?php
setlocale(LC_CTYPE, 'Portugese');
if (ctype_alnum('João'))
	echo 'Alphanumeric';
else
	echo 'Not alphanumeric';
?>

and it seems to work.