Using preg_split() to Split Strings with Regular Expressions in PHP

preg_split() is a PHP function that splits a string by a regular expression pattern, returning an array of substrings.

Signature:

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

Parameters: pattern – the regex pattern to search for; subject – the input string; limit – maximum number of splits (‑1, 0, or null means no limit); flags – bitwise combination of PREG_SPLIT_* constants such as PREG_SPLIT_NO_EMPTY, PREG_SPLIT_DELIM_CAPTURE, and PREG_SPLIT_OFFSET_CAPTURE.

Return value: an array of substrings (or arrays containing the substring and its offset when PREG_SPLIT_OFFSET_CAPTURE is used).

Example 1 splits a phrase using commas or whitespace:

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

Output:

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

Example 2 demonstrates using PREG_SPLIT_NO_EMPTY to remove empty elements:

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

Output shows each character as a separate element.

Example 3 shows PREG_SPLIT_OFFSET_CAPTURE to obtain substrings with their positions:

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

Output includes each word together with its offset in the original string.