A brief discussion on the difference between preg_match and preg_match_all functions in PHP

This article analyzes and introduces the preg_match function and preg_match_all function in PHP regular expressions. Friends in need can refer to it.

preg_match_all() function

Search in the given string according to the specified regular expression and match Take out the parts that fit the characteristics.

$pattern='/t(.*?)st/';
$str='tgvregbvst      test    tdst';
var_dump(preg_match_all($pattern,$str,$arr));
var_dump($arr);

We can see that the output result is:

int(3) array(2) { [0]=> array(3) { [0]=> string(10) "tgvregbvst" [1]=> string(4) "test" [2]=> string(4) "tdst" } [1]=> array(3) { [0]=> string(7) "gvregbv" [1]=> string(1) "e" [2]=> string(1) "d" } }

He lists all those that meet the conditions, but the preg_match() function is different.

preg_match() function

Performs a regular expression match and returns the number of pattern matches. Its value will be 0 (no match) or 1 because preg_match() will stop the search after the first match.

$pattern='/t(.*?)st/';
$str='tgvregbvst      test    tdst';
var_dump(preg_match($pattern,$str,$arr));
var_dump($arr);

We can see that the output result is:

int(1) array(2) { [0]=> string(10) "tgvregbvst" [1]=> string(7) "gvregbv" }

Compared with the previous function, the output result of this function is much less. This is their difference.

preg_match_all()Unlike the preg_match() function, it will search subject until it reaches the end. If an error occurs preg_match() returns false.

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