PHP 4, PHP 5, PHP 7, PHP 8
preg_quote - Quote regular expression characters

preg_quote( string$str, [string|null$delimiter = null] ): string

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: . \ + * ? [ ^ ] $ ( ) { } = ! < > | : - #

Note that / is not a special regular expression character.


Note that preg_quote is not meant to be applied to the $replacement string(s) of preg_replace etc.



The input string.


If the optional delimiter is 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 (escaped) string.



This function is binary-safe.


Version Description
7.3.0 The # character is now quoted
7.2.0 delimiter is nullable now.

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Example of preg_quote

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Function preg_quote:

Regular Expressions (Perl-Compatible) Functions

Most used PHP functions