preg_match
(PHP 3>= 3.0.9, PHP 4 )
preg_match -- Perform a regular expression match
Description
int
preg_match ( string pattern, string subject [, array matches [, int flags]])
Searches subject for a match to the regular
expression given in pattern.
If matches is provided, then it is filled
with the results of search. $matches[0] will contain the text that
matched the full pattern, $matches[1] will have the text that matched
the first captured parenthesized subpattern, and so on.
flags can be the following flag:
- PREG_OFFSET_CAPTURE
If this flag is set, for every occuring match the appendant string
offset will also be returned. Note that this changes the return value
in an array where every element is an array consisting of the matched
string at offset 0 and it's string offset into
subject at offset 1. This
flag is available since PHP 4.3.0 .
The
flags parameter is available since
PHP 4.3.0 .
preg_match() returns the number of times
pattern matches. That will be either 0 times
(no match) or 1 time because preg_match() will stop
searching after the first match. preg_match_all()
on the contrary will continue until it reaches the end of
subject.
preg_match() returns FALSE if an error occured.
Пример 1. Find the string of text "php" // the "i" after the pattern delimiter indicates a case-insensitive search
if (preg_match ("/php/i", "PHP is the web scripting language of choice.")) {
print "A match was found.";
} else {
print "A match was not found.";
} |
|
Пример 2. find the word "web" // the \b in the pattern indicates a word boundary, so only the distinct
// word "web" is matched, and not a word partial like "webbing" or "cobweb"
if (preg_match ("/\bweb\b/i", "PHP is the web scripting language of choice.")) {
print "A match was found.";
} else {
print "A match was not found.";
}
if (preg_match ("/\bweb\b/i", "PHP is the website scripting language of choice.")) {
print "A match was found.";
} else {
print "A match was not found.";
} |
|
Пример 3. Getting the domain name out of a URL // get host name from URL
preg_match("/^(http:\/\/)?([^\/]+)/i",
"http://www.php.net/index.html", $matches);
$host = $matches[2];
// get last two segments of host name
preg_match("/[^\.\/]+\.[^\.\/]+$/",$host,$matches);
echo "domain name is: ".$matches[0]."\n"; |
This example will produce:
|
See also
preg_match_all(),
preg_replace(), and
preg_split().