PHP also supports regular expressions using a Perl-compatible syntax using the PCRE functions. Those functions support non-greedy matching, assertions, conditional subpatterns, and a number of other features not supported by the POSIX-extended regular expression syntax.
These regular expression functions are not binary-safe. The PCRE functions are.
Regular expressions are used for complex string manipulation. PHP uses the POSIX extended regular expressions as defined by POSIX 1003.2. For a full description of POSIX regular expressions see the » regex man pages included in the regex directory in the PHP distribution. It's in manpage format, so you'll want to do something along the lines of man /usr/local/src/regex/regex.7 in order to read it.
Do not change the TYPE unless you know what you are doing.
To enable regexp support configure PHP
--with-regex[=TYPE]. TYPE can be one of
system, apache, php. The default is to use php.
The windows version of PHP has built in support for this extension. You do not need to load any additional extension in order to use these functions.
// Returns true if "abc" is found anywhere in $string.
// Returns true if "abc" is found at the beginning of $string.
// Returns true if "abc" is found at the end of $string.
// Returns true if client browser is Netscape 2, 3 or MSIE 3.
// Places three space separated words into $regs, $regs and $regs.
ereg("([[:alnum:]]+) ([[:alnum:]]+) ([[:alnum:]]+)", $string, $regs);
// Put a <br /> tag at the beginning of $string.
$string = ereg_replace("^", "<br />", $string);
// Put a <br /> tag at the end of $string.
$string = ereg_replace("$", "<br />", $string);
// Get rid of any newline characters in $string.
$string = ereg_replace("\n", "", $string);
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