CODEWITHSUNDEEP
phpregex
powerboy
powerboy

Reputation: 10961

PHP regex delimiters, / vs. | vs. {} , what are the differences?

In the PHP manual of PCRE, http://us.php.net/manual/en/pcre.examples.php, it gives 4 examples of valid patterns:

Seems that / , | or a pair of curly braces can use as delimiters, so is there any difference between them?

Upvotes: 10

Views: 8803

Answers (4)

anubhava
anubhava

Reputation: 785621

As per PHP Manual on regex delimiters

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

So essentially there is no difference between using slash or @ or #. However keep in mind that chosen delimiter must not appear in the regex itself otherwise you will need to escape that character.

Tip: Since PCRE allows any non-alphanumeric, non-backslash, non-whitespace as delimiter, sometimes it is better to use control characters as delimiters when you can't predict the content of regex being used. See below example:

$repl = preg_replace('^K^foo^K', 'bar', 'foo.txt' );

Here this code is using a control character ^K (typed as ctrl-V-K on shell)

Upvotes: 7

Ignacio Vazquez-Abrams
Ignacio Vazquez-Abrams

Reputation: 799130

Using / makes it harder to put a / in the regex or replacement. Using @ makes it harder to put a @ in the regex or replacement. Other than that, there is no difference.

Upvotes: 3

nico
nico

Reputation: 51670

In fact you can use any non alphanumeric delimiter (excluding whitespaces and backslashes)

"%^[a-z]%"

works as well as

"*^[a-z]*"

as well as

"!^[a-z]!"

Upvotes: 6

kennytm
kennytm

Reputation: 523534

No difference, except the closing delimiter cannot appear without escaping.

This is useful when the standard delimiter is used a lot, e.g. instead of 

preg_match("/^http:\\/\\/.+/", $str);

you can write

preg_match("[^http://.+]", $str);

to avoid needing to escape the /.

Upvotes: 7

Related Questions