What Delimiter to use for preg_replace in PHP (replace working outside of PHP but not inside)

Question

Myself and my team are stuck on this one, I have the following code.

$text = \"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut bibendum augue eu         


        

Answer 1

preg_replace() requires a delimiter character:

preg_replace("/$pat/" ...

Traditionally it's the forward slash, but it can be any character - especially when you need the forward slash in the regex itself you can resort to another character.

This flexibility allows you to express "/http:\/\/foo\/bar\//" ("leaning toothpick syndrome") as "!http://foo/bar/!".

The delimiter character is necessary to separate the regex from the regex flags (a.k.a. "modifiers"), for example:

preg_replace("/$pat/i" ...

…this uses the i flag to declare a case-insensitive regex.

Answer 2

try

$pat  = "/\[\[(.*)\|\|(.*)\]\]/m";

Answer 3

From the PHP manual on PCRE delimiters:

A delimiter can be any non-alphanumeric, non-backslash, non-whitespace character.

Often used delimiters are forward slashes (/), hash signs (#) and tildes (~).

So you could use / as delimiter to separate the pattern from optional modifiers:

/\[\[(.*)\|\|(.*)\]\]/

But also note:

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.

Furthermore, currently your pattern will match as much as possible as both quantifiers are greedy; you might want to change them to be reluctant to only match as little as possible:

/\[\[(.*?)\|\|(.*?)\]\]/