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POSIX Regex> <preg_replace
Last updated: Fri, 06 Nov 2009

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preg_split

(PHP 4, PHP 5)

preg_split — 正規表現で文字列を分割する

説明

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

指定した文字列を、正規表現で分割します。

パラメータ

pattern

検索するパターンを表す文字列。

subject

入力文字列。

limit

これを指定した場合、最大 limit 個の部分文字列を返します。 残りの文字列は、最後の部分文字列に含めて返されます。 limit が -1、0 あるいは null の場合は「制限が無い」ことを意味します。 制限を指定せずに flags パラメータを指定したい場合などに null を使用します。

flags

flags は、次のフラグを組み合わせたものとする （ビット和演算子｜で組み合わせる）ことが可能です。

PREG_SPLIT_NO_EMPTY
このフラグを設定すると、空文字列でないものだけが preg_split() により返されます。
PREG_SPLIT_DELIM_CAPTURE
このフラグを設定すると、文字列分割用のパターン中の カッコによるサブパターンでキャプチャされた値も同時に返されます。
PREG_SPLIT_OFFSET_CAPTURE

このフラグを設定した場合、各マッチに対応する文字列のオフセットも返されます。 これにより、返り値は配列となり、配列の要素 0 はマッチした文字列、 要素 1 は subject におけるマッチした文字列のオフセット値となることに 注意してください。

返り値

pattern にマッチした境界で分割した subject の部分文字列の配列を返します。

変更履歴

バージョン 説明
4.3.0 PREG_SPLIT_OFFSET_CAPTURE が追加されました。
4.0.5 PREG_SPLIT_DELIM_CAPTURE が追加されました。
4.0.0 パラメータ flags が追加されました。

例

例1 preg_split() の例 : 検索文字列のある部分を取得

<?php
// カンマまたは " ", \r, \t, \n , \f などの空白文字で句を分割する。
$keywords = preg_split("/[\s,]+/", "hypertext language, programming");
?>

例2 文字列を文字要素に分割

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

例3 文字列をマッチするものとそのオフセットに分割

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

上の例の出力は以下となります。

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

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

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

)

注意

ヒント

正規表現の威力を必要としないのなら、より高速な (機能はシンプルですが) 代替関数として explode() あるいは str_split() のような選択肢があります。

参考

  • spliti() - 大文字小文字を区別しない正規表現により文字列を分割し、配列に格納する
  • split() - 正規表現により文字列を分割し、配列に格納する
  • implode() - 配列要素を文字列により連結する
  • preg_match() - 正規表現によるマッチングを行う
  • preg_match_all() - 繰り返し正規表現検索を行う
  • preg_replace() - 正規表現検索および置換を行う



POSIX Regex> <preg_replace
Last updated: Fri, 06 Nov 2009
 
add a note add a note User Contributed Notes
preg_split
jan dot sochor at icebolt dot info
24-Oct-2009 07:26
Sometimes PREG_SPLIT_DELIM_CAPTURE does strange results.

<?php
$content = '<strong>Lorem ipsum dolor</strong> sit <img src="test.png" />amet <span class="test" style="color:red">consec<i>tet</i>uer</span>.';
$chars = preg_split('/<[^>]*[^\/]>/i', $content, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
print_r($chars);
?>
Produces:
Array
(
    [0] => Lorem ipsum dolor
    [1] =>  sit <img src="test.png" />amet
    [2] => consec
    [3] => tet
    [4] => uer
)

So that the delimiter patterns are missing. If you wanna get these patters remember to use parentheses.

<?php
$chars = preg_split('/(<[^>]*[^\/]>)/i', $content, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
print_r($chars); //parentheses added
?>
Produces:
Array
(
    [0] => <strong>
    [1] => Lorem ipsum dolor
    [2] => </strong>
    [3] =>  sit <img src="test.png" />amet
    [4] => <span class="test" style="color:red">
    [5] => consec
    [6] => <i>
    [7] => tet
    [8] => </i>
    [9] => uer
    [10] => </span>
    [11] => .
)
php at dmi dot me dot uk
06-Oct-2009 05:23
To split a camel-cased string using preg_split() with lookaheads and lookbehinds:

<?php
function splitCamelCase($str) {
  return preg_split('/(?<=\\w)(?=[A-Z])/', $str);
}
?>
Peter -the pete- de Pijd
24-Sep-2009 06:34
If you want to use something like explode(PHP_EOL, $string) but for all combinations of \r and \n, try this one:

<?php
$text = "A\nB\rC\r\nD\r\rE\n\nF";
$texts = preg_split("/((\r(?!\n))|((?<!\r)\n)|(\r\n))/", $text);
?>

result:
array("A", "B", "C", "D", "", "E", "", "F");
buzoganylaszlo at yahoo dot com
01-Aug-2009 04:57
Extending m.timmermans's solution, you can use the following code as a search expression parser:

<?php
$search_expression = "apple bear \"Tom Cruise\" or 'Mickey Mouse' another word";
$words = preg_split("/[\s,]*\\\"([^\\\"]+)\\\"[\s,]*|" . "[\s,]*'([^']+)'[\s,]*|" . "[\s,]+/", $search_expression, 0, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
print_r($words);
?>

The result will be:
Array
(
    [0] => apple
    [1] => bear
    [2] => Tom Cruise
    [3] => or
    [4] => Mickey Mouse
    [5] => another
    [6] => word
)

1. Accepted delimiters: white spaces (space, tab, new line etc.) and commas.

2. You can use either simple (') or double (") quotes for expressions which contains more than one word.
wf
29-May-2009 01:36
Spacing out your CamelCase using preg_replace:

<?php

function spacify($camel, $glue = ' ') {
    return preg_replace( '/([a-z0-9])([A-Z])/', "$1$glue$2", $camel );
}

echo spacify('CamelCaseWords'), "\n"; // 'Camel Case Words'
echo spacify('camelCaseWords'), "\n"; // 'camel Case Words'

?>
chris AT cmbuckley DOT co DOT uk
27-May-2009 07:11
Here's a helpful function to space out your CamelCase using preg_split:

<?php

function spacify($camel, $glue = ' ') {
    return $camel[0] . substr(implode($glue, array_map('implode', array_chunk(preg_split('/([A-Z])/',
        ucfirst($camel), -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE), 2))), 1);
}

echo spacify('CamelCaseWords'); // 'Camel Case Words'
echo spacify('camelCaseWords'); // 'camel Case Words'

?>
kenorb at gmail dot com
23-May-2009 11:56
If you need convert function arguments without default default values and references, you can try this code:

<?php
    $func_args = '$node, $op, $a3 = NULL, $form = array(), $a4 = NULL'
    $call_arg = preg_match_all('@(?<func_arg>\$[^,= ]+)@i', $func_args, $matches);
    $call_arg = implode(',', $matches['func_arg']);
?>
Result: string = "$node,$op,$a3,$form,$a4"
bit_kahuna at yahoo dot com
28-Mar-2009 04:02
how to display a shortened text string with an elipsis, but on word boundaries only.

<?php
function truncate($string, $max = 70, $rep = '...') {

    $words = preg_split("/[\s]+/", $string);
   
    $newstring = '';
    $numwords = 0;
   
    foreach ($words as $word) {
        if ((strlen($newstring) + 1 + strlen($word)) < $max) {
            $newstring .= ' '.$word;
            ++$numwords;
        } else {
            break;
        }
    }

    if ($numwords < count($words)) {
        $newstring .= $rep;
    }
   
    return $newstring;
}
?>

hope this helps someone!  thanks for all the help from everyone else!!
csaba at alum dot mit dot edu
18-Mar-2009 06:06
If the task is too complicated for preg_split, preg_match_all might come in handy, since preg_split is essentially a special case.

I wanted to split a string on a certain character (asterisk), but only if it wasn't escaped (by a preceding backslash).  Thus, I should ensure an even number of backslashes before any asterisk meant as a splitter.  Look-behind in a regular expression wouldn't work since the length of the preceding backslash sequence can't be fixed.  So I turned to preg_match_all:

<?php
// split a string at unescaped asterisks
// where backslash is the escape character
$splitter = "/\\*((?:[^\\\\*]|\\\\.)*)/";
preg_match_all($splitter, "*$string", $aPieces, PREG_PATTERN_ORDER);
$aPieces = $aPieces[1];

// $aPieces now contains the exploded string
// and unescaping can be safely done on each piece
foreach ($aPieces as $idx=>$piece)
  $aPieces[$idx] = preg_replace("/\\\\(.)/s", "$1", $piece);
?>
anajilly
17-Jul-2008 05:17
<?php
$s = '<p>bleh blah</p><p style="one">one two three</p>';

$htmlbits = preg_split('/(<p( style="[-:a-z0-9 ]+")?>|<\/p>)/i', $s, -1, PREG_SPLIT_DELIM_CAPTURE);

print_r($htmlbits);
?>

Array
(
    [0] =>
    [1] => <p>
    [2] => bleh blah
    [3] => </p>
    [4] =>
    [5] => <p style="one">
    [6] =>  style="one"
    [7] => one two three
    [8] => </p>
    [9] =>
)

two interesting bits:

1. When using PREG_SPLIT_DELIM_CAPTURE, if you use more than one pair of parentheses, the result array can have members representing all pairs.  See array indexes 5 and 6 to see two adjacent delimiter results in which the second is a subset match of the first.

2. If a parenthesised sub-expression is made optional by a following question mark (ex: '/abc (optional subregex)?/') some split delimiters may be captured in the result while others are not.  See array indexes 1 and 2 to see an instance where the overall match succeeded and returned a delimiter while the optional sub-expression '( style="[-:a-z0-9 ]+")?' did not match, and did not return a delimiter.  This means it's possible to have a result with an unpredictable number of delimiters in the result array.

This second aspect is true irrespective of the number of pairs of parentheses in the regex.  This means: in a regular expression with a single optional parenthesised sub-expression, the overall expression can match without generating a corresponding delimiter in the result.
m dot timmermans at home dot NOSPAM dot nl
29-May-2008 07:56
For people who want to use the double quote to group words/fields, kind of like CSV does, you can use the following expression:
<?php
$keywords = preg_split( "/[\s,]*\\\"([^\\\"]+)\\\"[\s,]*|[\s,]+/", "textline with, commas and \"quoted text\" inserted", 0, PREG_SPLIT_DELIM_CAPTURE );
?>
Which will result in:
Array
(
    [0] => textline
    [1] => with
    [2] => commas
    [3] => and
    [4] => quoted text
    [5] => inserted
)
crispytwo at yahoo dot com
05-Sep-2007 05:29
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.
Steve
24-Mar-2005 01:41
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:

<?php 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.
jetsoft at iinet.net.au
26-Sep-2004 12:01
To clarify the "limit" parameter and the PREG_SPLIT_DELIM_CAPTURE option,

<?php
$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 at codewhore dot org
30-May-2002 04:01
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.
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POSIX Regex> <preg_replace
Last updated: Fri, 06 Nov 2009
 
 
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