Note 014 Delimiter for PHP regular expressions

is written in front

The PHP regular delimiter used by Hy369 is slash (/, forward slash). I even thought that this was the only regular delimiter in PHP.

Hey, until today, I saw a rather strange example of using the # sign as a regular separator. Seeing this "strange" regular expression, I couldn't help but ask Du Niang. The result: I was stunned.

Really, until this moment, I realized that the regular separator under PHP is not actually only / .

Okay, let’s record this knowledge point that surprised Hy369.

PHP Regular expression delimiter

In PHP, the regular expression delimiter can be any character except: letters, numbers, backslashes, and whitespace characters.

Commonly used delimiters are: slash (/, forward slash), pound sign (#, hash sign) and tilde (~, tilde).

In other words, it can be the following patterns:

/test string/
#^[^0-9]Hy369$#
+php blog+
%[A-Za-z0-9_-]%

Key points

If in a certain pattern, the delimiter in this pattern needs to be used in the regular expression , you need to add a backslash before this separator. For example:

/http:\/\//

In this case, the entire regular expression is not very intuitive. At this time, you can consider changing a delimiter to enhance the readability of the regular expression. Therefore, the above regular expression can be replaced by this:

#http://#

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