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This article mainly introduces how many times the preg_match will match in php. It is very detailed and has a certain reference value. Friends who are interested must finish reading it!

The php preg_match () function matches once. The preg_match () function is used to search for matches on strings based on regular expressions, and can return the number of matches; the value of preg_match () will be 0 (mismatch) or 1, because it will stop searching after the first match.

Operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

The php preg_match () function matches once.

Php preg_match () function

The preg_match () function in PHP can search and match strings based on regular expressions. The syntax format of the function is as follows:

Preg_match ($pattern,$subject [, & $matches [, $flags = 0 [, $offset = 0])

The parameters are described as follows:

$pattern: the pattern to search for, that is, the edited regular expression

$subject: string to search for

$matches: optional parameter (array type), which will be populated with search results if $matches is provided. $matches [0] contains the text to which the full pattern matches, $matches [1] contains the text matched by the first capture subgroup, and so on

$flags: optional parameter. $flags can be set to PREG_OFFSET_CAPTURE. If this flag is passed, the string offset (relative to the target string) will be appended to the return for each occurrence of the match.

$offset: optional parameter that specifies where to start the search (in bytes) in the target string.

The preg_match () function can return the number of matches for $pattern, and its value will be 0 (mismatch) or 1, because preg_match () will stop searching after the first match.

Example: use the preg_match () function to search for a string

For the first match, the substring matching $pattern_1 is searched from the 8th bit of the string, and the $matches_2 array contains the matching substring and its location in the target string.

Note that the second regular expression is different from the first regular expression by adding a positioning symbol $to indicate the position at the end of the matching string.

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