Preg_match_all usage experience sharing_PHP tutorial-PHP Tutorial-php.cn

Preg_match_all usage experience sharing_PHP tutorial

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Release： 2016-07-13 10:39:54

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preg_match_all — perform global regular expression matching

Description

Copy code The code is as follows:

int preg_match_all ( string pattern, string subject, array matches [, int flags] )

Search for all content in subject that matches the regular expression given by pattern and put the results into matches in the order specified by flags.
After the first match is found, subsequent searches start from the end of the previous match.

Pay special attention to PREG_PATTERN_ORDER and PREG_SET_ORDER

flags can be a combination of the following flags (note that it does not make sense to use PREG_PATTERN_ORDER and PREG_SET_ORDER together):

If using PREG_PATTERN_ORDER

Sort the results so that $matches[0] is an array of all pattern matches, $matches[1] is an array of strings matched by the subpattern in the first bracket, and so on. (That is, $matches[0] [0] is the second item in all pattern matches, $matches[0] [1] is the second item in all pattern matches, $matches[1] [0] is the match for each item. The first item in brackets, $matches[1] [0] matches the second item in each bracket)

Copy code The code is as follows:

preg_match_all ("|<[^>] +>(.*)]+>|U","example:

this is a test

" ,$out, PREG_PATTERN_ORDER);

print $out[0][0].", ".$out[0][1]."n";
print $out[1][ 0].", ".$out[1][1]."n";
?>

This example will output:

Copy code The code is as follows:

example: ,

example: , this is a test

So, $out[0] contains the string matching the entire pattern, and $out[1] contains the string between a pair of HTML tags.
If using PREG_SET_ORDER

Sort the results so that $matches[0] is the array of the first set of matches, $matches[1] is the array of the second set of matches, and so on. (That is, $matches[0] [0] is the complete matching string in the first set of matches, $matches[0] [1] is the complete matching string in the first bracket in the first set of matches)

Copy code The code is as follows:

preg_match_all ("|<[^>] +>(.*)]+>|U","example:

this is a test

" ,$out, PREG_SET_ORDER);
print $out[0][0].", ".$out[0][1]."n";
print $out[1][0]. ", ".$out[1][1]."n";
?>

This example will output:

Copy code The code is as follows:

example: , example:
< ;div align=left>this is a test

, this is a test

In this example, $matches[0] is the first set of matching results, $matches[0][0] contains the text that matches the entire pattern, and $matches[0][1] contains the text that matches the first sub-pattern. text, and so on. Likewise, $matches[1] is the second set of matches, and so on.

PREG_OFFSET_CAPTURE

If this flag is set, the associated string offset of each matching result will also be returned. Note that this changes the value of the returned array so that each cell in it is also an array, where the first item is the matched string and the second item is its offset within the subject. This tag is available since PHP 4.3.0.
If no tag is given, PREG_PATTERN_ORDER is assumed.
Returns the number of times the entire pattern was matched (possibly zero), or FALSE on error.

Example 1. Get all phone numbers from a text

Copy code The code is as follows:

preg_match_all ("/(? (d)? ) ? (?(1) [-s] ) d-d/x","Call 555-1212 or 1-800-555-1212", $phones);
?>

Example 2. Search for matching HTML tags (greedy)

Copy code The code is as follows:

// \2 is an example of a backreference, its meaning in PCRE is
// must match the content within the second set of brackets in the regular expression itself , in this example
// is ([w]+). Because the string is in double quotes, you need
// to add an extra backslash.
$html = "bold textclick me";
preg_match_all ("/(<([w]+) [^>]*>)(.*)()/", $html, $matches);
for ($i=0; $i< count($matches[0 ]); $i++) {
echo "matched: ".$matches[0][$i]."n";
echo "part 1: ".$matches[1][$i]. "n";
echo "part 2: ".$matches[3][$i]."n";
echo "part 3: ".$matches[4][$i]."nn ";
}
?>

This example will output:

Copy code The code is as follows:

matched: bold text
part 1:
part 2: bold text
part 3:
matched: click me
part 1: < ;a href=howdy.html>
part 2: click me
part 3: