> -----Original Message-----
> From: John W. Holmes [mailto:[EMAIL PROTECTED]]
> Sent: 24 December 2002 00:44
>
> If you want to use some of PHP's special characters in your
> expression,
Don't you mean "preg's special characters"? Or even "PHP special characters which are
also preg special characters", as it's this duality of specialness that leads to the
necessity of double-escaping!
> such as $, you must escape it twice. For example:
>
> $matchme = "\$example";
> if (preg_match("/\$example/", $matchme)) {
>
> will not be matched because PHP interprets the \$ and passes it as $.
> Instead, you must do this:
>
> if (preg_match("/\\\$example/", $matchme)) {
This is the main reason I prefer to use *single*-quoted strings whenever possible in
preg_ calls -- the above could more legibly be written as:
if (preg_match('/\$example/', $matchme)) {
This is an instance where I'd even tend to prefer to write single-quoted strings
concatenated to bare variables, rather than using double-quoted strings and
variable-interpolation:
if (preg_match('/\$'.$example.'\./', $matchme)) {
rather than
if (preg_match("/\\\$$example\\./", $matchme)) {
Cheers!
Mike
---------------------------------------------------------------------
Mike Ford, Electronic Information Services Adviser,
Learning Support Services, Learning & Information Services,
JG125, James Graham Building, Leeds Metropolitan University,
Beckett Park, LEEDS, LS6 3QS, United Kingdom
Email: [EMAIL PROTECTED]
Tel: +44 113 283 2600 extn 4730 Fax: +44 113 283 3211
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