Using PHP preg_split() to Split Strings with Regular Expressions

The preg_split() function in PHP divides a string into an array using a regular expression pattern.

Syntax: array preg_split(string $pattern, string $subject, int $limit = -1, int $flags = 0)

Parameters

pattern : The regular expression used for splitting.

subject : The input string to be split.

limit : Maximum number of elements in the resulting array; -1 , 0 or null means no limit.

flags : Bitwise combination of flags such as PREG_SPLIT_NO_EMPTY (omit empty results), PREG_SPLIT_DELIM_CAPTURE (capture delimiters), and PREG_SPLIT_OFFSET_CAPTURE (include offset of each piece).

Return value

An array containing the substrings obtained after splitting the subject by the pattern.

Example 1 – Split by commas or whitespace

<?php
$keywords = preg_split("/[\s,]+/", "hypertext language, programming");
print_r($keywords);
?>

Output:

Array
(
    [0] => hypertext
    [1] => language
    [2] => programming
)

Example 2 – Split by a literal string and remove empty elements

<?php
$str = 'string';
$chars = preg_split('//', $str, -1, PREG_SPLIT_NO_EMPTY);
print_r($chars);
?>

Output:

Array
(
    [0] => s
    [1] => t
    [2] => r
    [3] => i
    [4] => n
    [5] => g
)

Example 3 – Split by spaces and capture offsets

<?php
$str = 'hypertext language programming';
$chars = preg_split('/ /', $str, -1, PREG_SPLIT_OFFSET_CAPTURE);
print_r($chars);
?>

Output (showing each substring with its offset in the original string):

Array
(
    [0] => Array
        (
            [0] => hypertext
            [1] => 0
        )
    [1] => Array
        (
            [0] => language
            [1] => 9
        )
    [2] => Array
        (
            [0] => programming
            [1] => 18
        )
)