Question

$str = "& &svnips   Â ∴ ≈ osidnviosd & sopinsdo";   
$regex = "/&[^\w;]/";
echo preg_replace($regex, "&", $str);

I’m trying to replace all un-encoded ampersands with encoded ones.
The problem is it’s removing the space between & and sopinsdo.

Any idea why?

Answer 1

Why use regex? Why not use htmlspecialchars()?

echo htmlspecialchars($str, ENT_NOQUOTES, 'UTF-8', false);

Note the fourth parameter. It tells it not to double encode anything. So basically, this will turn all < into <, all > into > and all & that are not part of an existing entity into &

But, if you must use regex, you could do:

$regex = '/&([^\w;])/';
echo preg_replace($regex, '&\1', $str);

Basically, it saves the non-word character and then adds it back…