PHP: Split string by a regular expression

Description

array preg_split ( string $pattern , string $subject [, int $limit [, int $flags ]] )

Split the given string by a regular expression.

Parameters

pattern

The pattern to search for, as a string.

subject

The input string.

limit

If specified, then only substrings up to limit are returned, and if limit is -1, it actually means "no limit", which is useful for specifying the flags .

flags

flags can be any combination of the following flags (combined with bitwise | operator):

PREG_SPLIT_NO_EMPTY: If this flag is set, only non-empty pieces will be returned by preg_split().
PREG_SPLIT_DELIM_CAPTURE: If this flag is set, parenthesized expression in the delimiter pattern will be captured and returned as well.
PREG_SPLIT_OFFSET_CAPTURE: If this flag is set, for every occurring 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 its string offset into subject at offset 1.

Return Values

Returns an array containing substrings of subject split along boundaries matched by pattern .

ChangeLog

Version Description

4.3.0 The PREG_SPLIT_OFFSET_CAPTURE was added

4.0.5 The PREG_SPLIT_DELIM_CAPTURE was added

4.0.0 The flags parameter was added

Examples

Example #1 preg_split() example : Get the parts of a search string


<?php

// split the phrase by any number of commas or space characters,

// which include " ", \r, \t, \n and \f

$keywords = preg_split("/[\s,]+/", "hypertext language, programming");

?>

Example #2 Splitting a string into component characters


<?php

$str = 'string';

$chars = preg_split('//', $str, -1, PREG_SPLIT_NO_EMPTY);

print_r($chars);

?>

Example #3 Splitting a string into matches and their offsets


<?php

$str = 'hypertext language programming';

$chars = preg_split('/ /', $str, -1, PREG_SPLIT_OFFSET_CAPTURE);

print_r($chars);

?>

The above example will output:

Array
(
    [0] => Array
        (
            [0] => hypertext
            [1] => 0
        )

    [1] => Array
        (
            [0] => language
            [1] => 10
        )

    [2] => Array
        (
            [0] => programming
            [1] => 19
        )

)

Notes

Tip

If you don't need the power of regular expressions, you can choose faster (albeit simpler) alternatives like explode() or str_split().