Delimitatori

Quando si usano le funzioni PCRE, il pattern deve essere racchiuso da delimitatori. Un delimitatore può essere qualsiasi carattere non alfanumerico, esclusi il backslash e i caratteri di spazio (spazio, tab, ecc.).

Delimitatori usati spesso sono la barra "slash" (/), il cancelletto "hash" (#) e la tilde (~). I seguenti sono esempi di delimitazioni valide dei pattern:

/foo bar/
#^[^0-9]$#
+php+
%[a-zA-Z0-9_-]%

If the delimiter needs to be matched inside the pattern it must be escaped using a backslash. If the delimiter appears often inside the pattern, it is a good idea to choose another delimiter in order to increase readability.

/http:\/\//
#http://#

The preg_quote() function may be used to escape a string for injection into a pattern and its optional second parameter may be used to specify the delimiter to be escaped.

In addition to the aforementioned delimiters, it is also possible to use bracket style delimiters where the opening and closing brackets are the starting and ending delimiter, respectively.

{this is a pattern}

You may add pattern modifiers after the ending delimiter. The following is an example of case-insensitive matching:

#[a-z]#i