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In the PHP manual of PCRE, http://us.php.net/manual/en/pcre.examples.php, it gives 4 examples of valid patterns:
/<\/\w+>/|(\d{3})-\d+|Sm/^(?i)php[34]/{^\s+(\s+)?$}Seems that / , | or a pair of curly braces can use as delimiters, so is there any difference between them?
750
Delimiters. The first element of a regular expression is the delimiters. These are the boundaries of your regular expressions. The most common delimiter that you'll see with regular expressions is the slash ( / ) or forward slash.
A delimiter can be any non-alphanumeric, non-backslash, non-whitespace character. Leading whitespace before a valid delimiter is silently ignored. Often used delimiters are forward slashes ( / ), hash signs ( # ) and tildes ( ~ ).
Definition and Usage The preg_match() function returns whether a match was found in a string.
\s stands for “whitespace character”. Again, which characters this actually includes, depends on the regex flavor. In all flavors discussed in this tutorial, it includes [ \t\r\n\f]. That is: \s matches a space, a tab, a carriage return, a line feed, or a form feed.
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 /.
109
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]!"
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