Split string by a regular expression

- « preg_replace_callback_array

- ssdeep »

- PHP Manual
- PCRE Functions
- Split string by a regular expression

# preg_split

(PHP 4, PHP 5, PHP 7, PHP 8)

preg_split — Split string by a regular expression

### Description

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

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 with the rest of the string being placed in the last substring. A `limit` of -1 or 0 means "no limit".

`flags`

  `flags` can be any combination of the following flags (combined with the `|` 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`, or `false` on failure.

### Errors/Exceptions

If the regex pattern passed does not compile to a valid regex, an `E_WARNING` is emitted.

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

The above example will output:

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

Example #2 Splitting a string into component characters

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

The above example will output:

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

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().

Tip

If matching fails, an array with a single element containing the input string will be returned.

### See Also

- PCRE Patterns
- preg_quote() - Quote regular expression characters
- implode() - Join array elements with a string
- preg_match() - Perform a regular expression match
- preg_match_all() - Perform a global regular expression match
- preg_replace() - Perform a regular expression search and replace
- preg_last_error() - Returns the error code of the last PCRE regex execution