Re: [PHP] Unable to match dollar sign in preg_match
John W. Holmes wrote:
I don't know. I just got that from reading the manual. The very first
user comment on the preg_match page.
to put a literal dollar sign in a regex it has to be escaped \$
to put a backslash in a double quoted string you have to escape it \\$
in order to put a literal dollar sign in a double quoted string you have
to escape it \\\$
or you can use sinlgle quotes - where you only have to escape the dollar
sign once to mark it a a literal dollar sign and not an end string/line
placeholder
preg_match('/\$example/' , $matchme))
Sean
chrisbolt at home dot com
12-Mar-2000 03:23
If you want to use some of PHP's special characters in your expression,
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/", $matchme)) {
---
Don't forget to check the manual.
---John W. Holmes...
PHP Architect - A monthly magazine for PHP Professionals. Get your copy
today. http://www.phparch.com/
-Original Message-
From: Randall Perry [mailto:[EMAIL PROTECTED]]
Sent: Monday, December 23, 2002 4:07 PM
To: [EMAIL PROTECTED]
Subject: Re: [PHP] Unable to match dollar sign in preg_match
Hokay, that works, but what's with the triple backslashes?
preg_match ("/^.*_\%split\%_$(\d*\.\d*)/", $data, $match);
Should be
preg_match ("/^.*_\%split\%_\\\$(\d*\.\d*)/", $data, $match);
---John W. Holmes...
PHP Architect - A monthly magazine for PHP Professionals. Get your
copy
today. http://www.phparch.com/
--
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sysTame
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RE: [PHP] Unable to match dollar sign in preg_match
> -Original Message- > From: John W. Holmes [mailto:[EMAIL PROTECTED]] > Sent: 24 December 2002 00:44 > > I don't know. I just got that from reading the manual. The very first > user comment on the preg_match page. Sorry, misread this before and took the explanation below as John replying to chrisbolt -- but actually, it's John *quoting* chrisbolt, isn't it? In which case, I'll chip in further with: > > chrisbolt at home dot com > 12-Mar-2000 03:23 > > If you want to use some of PHP's special characters in your > expression, > such as $, you must escape it twice. For example: $ is both a PHP special character in double-quoted strings, and a special character in preg pattern matches (meaning "start of string or line") -- so it first has to be escaped for preg, giving \$, and then the \ and the $ each have to be escaped for the PHP double-quoted string giving "\\\$". Basically, if you put your pattern in a double-quoted string, every time you want to pass a \ to preg (say as an escape for a special character such as ., or as part of a character class such as \d) you have to assess whether it needs escaping for PHP, leading to a double backslash in the PHP string. The safest strategy is just to double it every time, as this will always be de-escaped by PHP to a single \ in the string which is then passed to preg. If you use single-quoted strings for your preg pattern, you don't get this problem as the only character that needs escaping for PHP is then the single quote itself! 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 -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
RE: [PHP] Unable to match dollar sign in preg_match
> -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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RE: [PHP] Unable to match dollar sign in preg_match
I don't know. I just got that from reading the manual. The very first
user comment on the preg_match page.
chrisbolt at home dot com
12-Mar-2000 03:23
If you want to use some of PHP's special characters in your expression,
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/", $matchme)) {
---
Don't forget to check the manual.
---John W. Holmes...
PHP Architect - A monthly magazine for PHP Professionals. Get your copy
today. http://www.phparch.com/
> -Original Message-
> From: Randall Perry [mailto:[EMAIL PROTECTED]]
> Sent: Monday, December 23, 2002 4:07 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [PHP] Unable to match dollar sign in preg_match
>
> Hokay, that works, but what's with the triple backslashes?
>
>
> >> preg_match ("/^.*_\%split\%_$(\d*\.\d*)/", $data, $match);
> >
> > Should be
> >
> > preg_match ("/^.*_\%split\%_\\\$(\d*\.\d*)/", $data, $match);
> >
> > ---John W. Holmes...
> >
> > PHP Architect - A monthly magazine for PHP Professionals. Get your
copy
> > today. http://www.phparch.com/
> >
> >
>
> --
> Randall Perry
> sysTame
>
> Xserve Web Hosting/Co-location
> Website Development/Promotion
> Mac Consulting/Sales
>
> http://www.systame.com/
>
>
>
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Re: [PHP] Unable to match dollar sign in preg_match
Hokay, that works, but what's with the triple backslashes?
>> preg_match ("/^.*_\%split\%_$(\d*\.\d*)/", $data, $match);
>
> Should be
>
> preg_match ("/^.*_\%split\%_\\\$(\d*\.\d*)/", $data, $match);
>
> ---John W. Holmes...
>
> PHP Architect - A monthly magazine for PHP Professionals. Get your copy
> today. http://www.phparch.com/
>
>
--
Randall Perry
sysTame
Xserve Web Hosting/Co-location
Website Development/Promotion
Mac Consulting/Sales
http://www.systame.com/
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RE: [PHP] Unable to match dollar sign in preg_match
> preg_match ("/^.*_\%split\%_$(\d*\.\d*)/", $data, $match);
Should be
preg_match ("/^.*_\%split\%_\\\$(\d*\.\d*)/", $data, $match);
---John W. Holmes...
PHP Architect - A monthly magazine for PHP Professionals. Get your copy
today. http://www.phparch.com/
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