Is it ok to use £ as delimiter in preg_replace?

Question

I am converting an eregi_replace function I found to preg_replace, but the eregi string has about every character on the keyboard in it. So I tried to use £ as the delimiter.. and it is working currently, but I wonder if it might potentially cause problems because it is a non-standard character?

Here is the eregi:

function makeLinks($text) {  
$text = eregi_replace('(((f|ht){1}tp://)[-a-zA-Z0-9@:%_\+.~#?&//=]+)',
'<a href="\\1">\\1</a>', $text);
$text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_\+.~#?&//=]+)',
'\\1<a href="http://\\2">\\2</a>', $text);

    return $text;}

and the preg:

function makeLinks($text) {
    $text = preg_replace('£(((f|ht){1}tp://)[-a-zA-^Z0-9@:%_\+.~#?&//=]+)£i',
    '<a href="\\1">\\1</a>', $text);
    $text = preg_replace('£([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_\+.~#?&//=]+)£i',
    '\\1<a href="http://\\2">\\2</a>', $text);

        return $text;
}

Answer 1

£ is problematic because it isn't an ASCII character. It's from the Latin-1 charset and will only work if your PHP script also uses the 8bit representation. Should your file be encoded as UTF-8, then £ will be represented as two bytes. And PCRE in PHP will trip over that. (At least my version does.)