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PHP : Function Reference : Regular Expression Functions (Perl-Compatible) : preg_split

preg_split

Split string by a regular expression (PHP 4, PHP 5)
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 1732. preg_split() example : Get the parts of a search string

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<?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 1733. Splitting a string into component characters

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


Example 1734. Splitting a string into matches and their offsets

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

The above example will output:

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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().

See Also
spliti()
split()
implode()
preg_match()
preg_match_all()
preg_replace()

Related Examples ( Source code ) » preg_split

Examples ( Source code ) » preg_split (/\+{1,}/)
Examples ( Source code ) » Splitting a String Based on a Found String

Code Examples / Notes » preg_split

me
[Editor's Note: You can use php's wordwrap() to do the exact same thing]
This script splits a text into portions of a defined max. size, which will never be exceeded, and doesnt cut words. (Per portion it adds as many words as possible without exceeding the char-limit)
the only exception where a portion would be bigger than the limit, is when there's a word thats longer than the max_size, but you could quite easily change the script so it regards this.
<?
$str= 'Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.';
$max_size = 50;
$words = preg_split("/[\040]+/", $str, -1);
$r=0;
for($i=0; $i < count($words); $i++) {
if (strlen($line[$r] . $words[$i] . ' ') < $max_size) $line[$r] .= $words[$i] . ' ';
else
{
$r++;
$line[$r] .= $words[$i] . ' ';
}
}
print_r ($line);
?>
Result:
Array
(
   [0] => Lorem ipsum dolor sit amet, consectetur
   [1] => adipisicing elit, sed do eiusmod tempor
   [2] => incididunt ut labore et dolore magna aliqua. Ut
   [3] => enim ad minim veniam, quis nostrud exercitation
   [4] => ullamco laboris nisi ut aliquip ex ea commodo
   [5] => consequat. Duis aute irure dolor in
   [6] => reprehenderit in voluptate velit esse cillum
   [7] => dolore eu fugiat nulla pariatur. Excepteur sint
   [8] => occaecat cupidatat non proident, sunt in culpa
   [9] => qui officia deserunt mollit anim id est laborum.
)

jetsoft
To clarify the "limit" parameter and the PREG_SPLIT_DELIM_CAPTURE option,
$preg_split('(/ /)', '1 2 3 4 5 6 7 8', 4 ,PREG_SPLIT_DELIM_CAPTURE );
returns
('1', ' ', '2', ' ' , '3', ' ', '4 5 6 7 8')
So you actually get 7 array items not 4

dave
The above description for PREG_SPLIT_OFFSET_CAPTURE may be a bit confusing.
When the flag is or'd into the 'flags' parameter of preg_split, each match is returned in the form of a two-element array. For each of the two-element arrays, the first element is the matched string, while the second is the match's zero-based offset in the input string.
For example, if you called preg_split like this:
preg_split('/foo/', 'matchfoomatch', -1, PREG_SPLIT_OFFSET_CAPTURE);
it would return an array of the form:
Array(
 [0] => Array([0] => "match", [1] => 0),
 [1] => Array([1] => "match", [1] => 8)
)
Note that or'ing in PREG_DELIM_CAPTURE along with PREG_SPLIT_OFFSET_CAPTURE works as well.

steve
preg_split() behaves differently from perl's split() if the string ends with a delimiter. This perl snippet will print 5:
my @a = split(/ /, "a b c d e ");
print scalar @a;
The corresponding php code prints 6:
print count(preg_split("/ /", "a b c d e "));
This is not necessarily a bug (nowhere does the documentation say that preg_split() behaves the same as perl's split()) but it might surprise perl programmers.

crispytwo
I was having trouble getting the PREG_SPLIT_DELIM_CAPTURE flag to work because I missed reading the "parenthesized expression" in the documentation :-(  
So the pattern should look like:
/(A)/
not just
/A/
and it works as described/expected.

superzouz
Be advised
$arr = preg_split("/x/", "x" );
print_r($arr);
will output:
Array
(
   [0] =>
   [1] =>
)
That is it will catch the 2 empty string on each side of the delimiter.

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