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This article mainly introduces "how to use global regular expression matching and array elements matching in PHP". In daily operation, I believe that many people have doubts about how to use global regular expression matching and array elements matching in PHP. The editor consulted all kinds of materials and sorted out simple and useful operation methods. I hope it will be helpful to answer the question of "how to use global regular expressions to match and match array elements in PHP"! Next, please follow the editor to study!

Preg_match_all () function

Previously, we only introduced the preg_match () function, a basic function, and there is also a function in PHP that is very similar to the preg_match () function-- preg_match_all (), which searches for all the results in a string that match a regular expression.

The syntax format of this function is as follows:

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

Among them, it should be noted that:

$pattern represents the pattern to search, that is, the defined regular expression; $subject represents the string to be searched; $matches indicates that the optional parameter is a multi-dimensional array that holds all matching results, and the array sort is specified by $flags; $offset represents the optional parameter, and $offset is used to start the search from the specified position in the target string, which is in bytes.

$flags represents an optional parameter, where it can be used in combination with the following tags

PREG_PATTERN_ORDER

The result is sorted as $matches [0] to save all matches for the full pattern, $matches [1] to save all matches for the first subgroup, and so on.

PREG_SET_ORDER

The order of the result is $matches [0] containing all matches (including subgroups) from the first match, $matches [1] is an array containing all matches (including subgroups) from the second match, and so on.

PREG_OFFSET_CAPTURE

If this tag is passed, each found match returns with an increase in its offset from the target string. Note that this changes each matching result string element in $matches so that the 0th element is the matching result string, and the first element is the offset of the matching result string in the subject.

You cannot use the PREG_PATTERN_ORDER and PREG_SET_ORDER,preg_match_all () functions at the same time to return the number of matches for $pattern (which may be 0) and FALSE if an error occurs.

Next, let's take a look at the application of the preg_match_all () function through an example, matching a string. The example is as follows:

Output result:

From the above example, we have finished matching a string through the preg_match_all () function. Through the application of the preg_match_all () function, we can complete the global regular expression matching.

Next, let's take a look at how to detect array elements that match a given pattern. This is the time to use the preg_grep () function.

Preg_grep () function

Using regular expressions, you can match elements in an array as well as strings. The preg_grep () function in PHP searches for all the elements in the array and returns an array of all elements that match the regular expression. The syntax format of this function is as follows:

Preg_grep ($pattern, $input [, $flags = 0])

Among them, it should be noted that:

$pattern represents the pattern to search, that is, the defined regular expression; $input represents the array to search; and $flags represents the optional parameter, which can be set to PREG_GREP_INVERT, in which case the function returns an array of elements in the array that do not match the given pattern $pattern. The perg_grep () function iterates through each element in the $input array, matches that element to the pattern $pattern, and then returns elements that succeed or fail.

Next, let's take a look at using the perg_grep () function to match elements in an array, as shown in the following example:

Output result:

The example above is to match the elements in the array through the preg_grep () function.

At this point, the study on "how to use global regular expressions to match and match array elements in PHP" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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