preg_match
If you need to quote everything but a wildcard, maybe this function will come handy to you:
<?php
protected function _ruleOptionIsMatched($option, $subject)
{
$option = preg_quote($option, '#');
$option = str_replace('\*', '.*', $option);
if(preg_match("#^$option$#", $subject))
{
return true;
}
else
{
return false;
}
}
?>
preg_quote
(PHP 4, PHP 5)
preg_quote — Quote regular expression characters
Description
string preg_quote
( string
$str
[, string $delimiter = NULL
] )
preg_quote() takes str
and puts a backslash in front of every character that is part of
the regular expression syntax. This is useful if you have a
run-time string that you need to match in some text and the
string may contain special regex characters.
The special regular expression characters are: . \ + * ? [ ^ ] $ ( ) { } = ! < > | : -
Parameters
-
str -
The input string.
-
delimiter -
If the optional
delimiteris specified, it will also be escaped. This is useful for escaping the delimiter that is required by the PCRE functions. The / is the most commonly used delimiter.
Return Values
Returns the quoted string.
Changelog
| Version | Description |
|---|---|
| 5.3.0 | The - character is now quoted |
Examples
Example #1 preg_quote() example
<?php
$keywords = '$40 for a g3/400';
$keywords = preg_quote($keywords, '/');
echo $keywords; // returns \$40 for a g3\/400
?>
Example #2 Italicizing a word within some text
<?php
// In this example, preg_quote($word) is used to keep the
// asterisks from having special meaning to the regular
// expression.
$textbody = "This book is *very* difficult to find.";
$word = "*very*";
$textbody = preg_replace ("/" . preg_quote($word) . "/",
"<i>" . $word . "</i>",
$textbody);
?>
Notes
Note: This function is binary-safe.
add a note
User Contributed Notes
preg_quote - [9 notes]
billadoid at gmail dot com ¶
1 year ago
Anonymous ¶
5 years ago
Wondering why your preg_replace fails, even if you have used preg_quote?
Try adding the delimiter / - preg_quote($string, '/');
bizzigul at hotmail dot fr ¶
4 years ago
To prevent any problems, try to always use a delimiter that will *almost* not be used inside the regex, such as ` (back quote)
for example: instead of
<?php preg_match('/foo\/bar\//',$somevar); ?>
use
<?php preg_match('`foo/bar/`',$somevar); ?>
it's that simple! like this, you won't have to bother with delimiters anymore...
zooly ¶
3 years ago
To escape characters with special meaning, like: .-[]() and so on, use \Q and \E.
For example:
<?php echo ( preg_match('/^'.( $myvar = 'te.t' ).'$/i', 'test') ? 'match' : 'nomatch' ); ?>
Will result in: match
But:
<?php echo ( preg_match('/^\Q'.( $myvar = 'te.t' ).'\E$/i', 'test') ? 'match' : 'nomatch' ); ?>
Will result in: nomatch
krishoog at gmail dot com ¶
4 years ago
To bizzigul at hotmail dot fr:
It's not a good practice to make somthing work *almost* all of the time. If the input contains a '`' you will still get an error. I recommend using the default delimiter ('/') and also feed this to preg_quote as second argument.
php at richardneill dot org ¶
1 month ago
preg_quote() only works on the search string, not the replacement string.
But the replacement string isn't always literal, as it can contain backreferences.
There's no function to quote the replacement string, but a workaround is to escape all $ and \ signs:
$replace = str_replace (array('\\','$'),array('\\\\','\$'),$replace);
For example:
$text = 'Test: *#5*';
$search = "*#5*";
$replace = "*$5\\1*";
$search = preg_quote($search, "/");
$replace = str_replace (array('\\','$'),array('\\\\','\$'),$replace);
$new = preg_replace("/$search/", "$replace", $text);
echo "Input: $text\nOutput: $new\n";
Prints:
Input: Test: *#5*
Output: Test: *$5\1*
admin at nilamo dot com ¶
2 years ago
@zooly:
And what if $myvar = 'te\\E.t'? It will match, when it shouldn't. That's why you should use preg_quote().
alexc223 at NOSPAM dot googlemail dot com ¶
3 years ago
Not sure why this note got deleted, but hey lets try again:
As of PHP 5.3, bug #47229 has been fixed and preg_quote *will* escape a hyphen (-). This may effect your code so ensure this is one thing you check when moving to 5.3.
frostschutz ¶
4 years ago
I wanted to escape a string of characters so I could match them in [], i.e. [.,-!"ยง$%\\\[\]\^].
Unfortunately preg_quote does not escape the - character which has a special meaning in [], i.e. [a-z].
So I used this hack: make - the delimiter of the expression, i.e.
preg_quote(userinput, "-")
preg_replace("-[$userinput]-u", "", $str)
Apparently using a special char as a delimiter of a regular expression disables this character, i.e. even if it's escaped it's not understood as special character for the expression anymore.
so the pattern "-[a\\-z]-u" matches the characters a, - and z, and not abc...xyz.
It would be nice if preg_quote also escaped characters that have special meanings even if they have this meaning only under certain conditions, such as inside [].