explode()

(PHP 4, PHP 5, PHP 7)

使用一个字符串分割另一个字符串

说明

explode(string $delimiter, string $string[,int $limit] ): array

此函数返回由字符串组成的数组，每个元素都是$string的一个子串，它们被字符串$delimiter作为边界点分割出来。

参数

$delimiter

边界上的分隔字符。

$string

输入的字符串。

$limit

如果设置了$limit参数并且是正数，则返回的数组包含最多$limit个元素，而最后那个元素将包含$string的剩余部分。

如果$limit参数是负数，则返回除了最后的-$limit个元素外的所有元素。

如果$limit是 0，则会被当做 1。

由于历史原因，虽然implode()可以接收两种参数顺序，但是explode()不行。你必须保证$separator参数在$string参数之前才行。

返回值

此函数返回由字符串组成的array，每个元素都是$string的一个子串，它们被字符串$delimiter作为边界点分割出来。

如果$delimiter为空字符串（""），explode()将返回FALSE。如果$delimiter所包含的值在$string中找不到，并且使用了负数的$limit，那么会返回空的array，否则返回包含$string单个元素的数组。

更新日志

范例

Example #1explode()例子

<?php
// 示例 1
$pizza  = "piece1 piece2 piece3 piece4 piece5 piece6";
$pieces = explode(" ", $pizza);
echo $pieces[0]; // piece1
echo $pieces[1]; // piece2
// 示例 2
$data = "foo:*:1023:1000::/home/foo:/bin/sh";
list($user, $pass, $uid, $gid, $gecos, $home, $shell) = explode(":", $data);
echo $user; // foo
echo $pass; // *
?>

Example #2explode()return examples

<?php
/* A string that doesn't contain the delimiter will simply return a one-length array of the original string. */
$input1 = "hello";
$input2 = "hello,there";
var_dump( explode( ',', $input1 ) );
var_dump( explode( ',', $input2 ) );
?>

以上例程会输出：

array(1)
(
    [0] => string(5) "hello"
)
array(2)
(
    [0] => string(5) "hello"
    [1] => string(5) "there"
)

Example #3$limit参数的例子

<?php
$str = 'one | two | three | four';
// 正数的 limit
print_r(explode(' | ', $str, 2));
// 负数的 limit（自 PHP 5.1 起）
print_r(explode(' | ', $str, -1));
?>

以上例程会输出：

Array
(
    [0] => one
    [1] => two | three | four
)
Array
(
    [0] => one
    [1] => two
    [2] => three
)

注释

Note:此函数可安全用于二进制对象。

参见

• preg_split()通过一个正则表达式分隔字符串
• str_split()将字符串转换为数组
• mb_split()使用正则表达式分割多字节字符串
• str_word_count()返回字符串中单词的使用情况
• strtok()标记分割字符串
• implode()将一个一维数组的值转化为字符串

Here is my approach to have exploded output with multiple delimiter. 
<?php
//$delimiters has to be array
//$string has to be array
function multiexplode ($delimiters,$string) {
  
  $ready = str_replace($delimiters, $delimiters[0], $string);
  $launch = explode($delimiters[0], $ready);
  return $launch;
}
$text = "here is a sample: this text, and this will be exploded. this also  |  this one too :)";
$exploded = multiexplode(array(",","."," | ",":"),$text);
print_r($exploded);
//And output will be like this:
// Array
// (
//  [0] => here is a sample
//  [1] => this text
//  [2] => and this will be exploded
//  [3] => this also 
//  [4] => this one too 
//  [5] => )
// )
?>

Beaware splitting empty strings.
<?php
$str = "";
$res = explode(",", $str);
print_r($res);
?>
If you split an empty string, you get back a one-element array with 0 as the key and an empty string for the value.
Array
(
  [0] => 
)
To solve this, just use array_filter() without callback. Quoting manual page "If the callback function is not supplied, array_filter() will remove all the entries of input that are equal to FALSE.".
<?php
$str = "";
$res = array_filter(explode(",", $str));
print_r($res);
?>
Array
(
)

The comments to use array_filter() without a callback to remove empty strings from explode's results miss the fact that array_filter will remove all elements that, to quote the manual, "are equal to FALSE".
This includes, in particular, the string "0", which is NOT an empty string.
If you really want to filter out empty strings, use the defining feature of the empty string that it is the only string that has a length of 0. So:
<?php
array_filter(explode(':', "1:2::3:0:4"), 'strlen');
?>

a simple one line method to explode & trim whitespaces from the exploded elements
array_map('trim',explode(",",$str));
example:
$str="one ,two ,    three , four  "; 
print_r(array_map('trim',explode(",",$str)));
Output:
Array ( [0] => one [1] => two [2] => three [3] => four )

It toke me about 1 day to find out the problem. (almost?) every function in PHP has a logical build as argument 1: Entity where the operation is based upon and 2 - the operand in the process. But with the explode-function the order is reversed and different. First the operand (delimiter) and second the string to be managed. Not quite logical compared to other needle-haystack-functions. And yes, If you're reading the format it should be no problem. Just hoping to help somebody else.

Here's a function for "multi" exploding a string.
<?php
//the function
//Param 1 has to be an Array
//Param 2 has to be a String
function multiexplode ($delimiters,$string) {
  $ary = explode($delimiters[0],$string);
  array_shift($delimiters);
  if($delimiters != NULL) {
    foreach($ary as $key => $val) {
       $ary[$key] = multiexplode($delimiters, $val);
    }
  }
  return $ary;
}
// Example of use
$string = "1-2-3 | 4-5 | 6:7-8-9-0 | 1,2:3-4 | 5";
$delimiters = Array(",",":"," | ","-");
$res = multiexplode($delimiters,$string);
echo '<pre>';
print_r($res);
echo '</pre>';
//returns
/*
Array
(
  [0] => Array
    (
      [0] => Array
        (
          [0] => Array
            (
              [0] => 1
              [1] => 2
              [2] => 3
            )
          [1] => Array
            (
              [0] => 4
              [1] => 5
            )
          [2] => Array
            (
              [0] => 6
            )
        )
      [1] => Array
        (
          [0] => Array
            (
              [0] => 7
              [1] => 8
              [2] => 9
              [3] => 0
            )
          [1] => Array
            (
              [0] => 1
            )
        )
    )
  [1] => Array
    (
      [0] => Array
        (
          [0] => Array
            (
              [0] => 2
            )
        )
      [1] => Array
        (
          [0] => Array
            (
              [0] => 3
              [1] => 4
            )
          [1] => Array
            (
              [0] => 5
            )
        )
    )
)
*/
?>

I made this code for some useful filtering texts with lot of gibberish. Example provided:
<?php
$text = "There are;many | variations of:passages of Lorem Ipsum available,but the/majority have\"suffered | alteration in some form,by injected humour,or randomised words which don't look even.slightly:believable./";
$delimiter = array(" ",",",".","'","\""," | ","\\","/",";",":");
$replace = str_replace($delimiter, $delimiter[0], $text);
$explode = explode($delimiter[0], $replace);
echo '<pre>';
print_r($explode);
echo '</pre>';
// replaces many symbols in text, then explodes it
?>
This will output the following:
Array
(
  [0] => There
  [1] => are
  [2] => many
  [3] => variations
  [4] => of
  [5] => passages
  [6] => of
  [7] => Lorem
  [8] => Ipsum
  [9] => available
  [10] => but
  [11] => the
  [12] => majority
  [13] => have
  [14] => suffered
  [15] => alteration
  [16] => in
  [17] => some
  [18] => form
  [19] => by
  [20] => injected
  [21] => humour
  [22] => or
  [23] => randomised
  [24] => words
  [25] => which
  [26] => don
  [27] => t
  [28] => look
  [29] => even
  [30] => slightly
  [31] => believable
  [32] => 
  [33] => 
)

<?php
functinon metaExplode(string $za = '', string $lu = '', string $pa = '') {
  return explode($za . ',' . $lu . ',' . $pa, ',');
}

<?php
// converts pure string into a trimmed keyed array
function string2KeyedArray($string, $delimiter = ',', $kv = '=>') {
 if ($a = explode($delimiter, $string)) { // create parts
  foreach ($a as $s) { // each part
   if ($s) {
    if ($pos = strpos($s, $kv)) { // key/value delimiter
     $ka[trim(substr($s, 0, $pos))] = trim(substr($s, $pos + strlen($kv)));
    } else { // key delimiter not found
     $ka[] = trim($s);
    }
   }
  }
  return $ka;
 }
} // string2KeyedArray
$string = 'a=>1, b=>23  , $a, c=> 45% , true,d => ab c ';
print_r(string2KeyedArray($string));
?>
Array
(
 [a] => 1
 [b] => 23
 [0] => $a
 [c] => 45%
 [1] => true
 [d] => ab c
)

Explode does not parse a string by delimiters, in the sense that we expect to find tokens between a starting and ending delimiter, but instead splits a string into parts by using a string as the boundary of each part. Once that boundary is discovered the string is split. Whether or not that boundary is proceeded or superseded by any data is irrelevant since the parts are determined at the point a boundary is discovered. 
For example: 
<?php 
var_dump(explode("/","/")); 
/* 
  Outputs 
  array(2) { 
   [0]=> 
   string(0) "" 
   [1]=> 
   string(0) "" 
  } 
*/ 
?> 
The reason we have two empty strings here is that a boundary is discovered before any data has been collected from the string. The boundary splits the string into two parts even though those parts are empty. 
One way to avoid getting back empty parts (if you don't care for those empty parts) is to use array_filter on the result. 
<?php 
var_dump(array_filter(explode("/","/"))); 
/* 
  Outputs 
  array(0) { 
  } 
*/ 
?> 
*[This note was edited by googleguy at php dot net for clarity]*

I needed a multiexplode which didn't replace my delimiters for 1 other delimiter. Because I couldn't find one in the examples I made one.
delimiter array:
array('/RTRN/','/BUSP/','/BENM/','/ORDP/','/CSID/', '/MARF/','/EREF/', '/PREF/','/REMI/','/ID/','/PURP/', '/ULTB/','/ULTD/');
input string: /RTRN/MS03//BENM/NL50INGB00012345/BUSP/Europese Incasso/eenmalig/67/INGBNL2A/ING Bank N.V. inzake WeB///CSID/NL32ZZZ999999991234//MARF/EV45451//EREF/EV45451 REP170112T1106//REMI///EV45451REP170112T1106/
output:
array(
[/RTRN/] => MS03/
[/BENM/] => NL50INGB00012345
[/BUSP/] => Europese Incasso/eenmalig/67/INGBNL2A/ING Bank N.V. inzake WeB//
[/CSID/] => NL32ZZZ999999991234/
[/MARF/] => EV45451/
[/EREF/] => EV45451REP170112T1106/
[/REMI/] => //EV45451REP170112T1106/
[/ORDP/] => 
[/PREF/] => 
[/ID/] => 
[/PURP/] => 
[/ULTB/] => 
[/ULTD/] =>
)
<?php
function multiexplode($delimiters,$string) {
      
    $arrOccurence = array();
    $arrEnd = array();
    foreach($delimiters as $key => $value){
      $position = strpos($string, $value);
      if($position > -1){
        $arrOccurence[$value] = $position;
      }
    }
    
    if(count($arrOccurence) > 0){
        
      asort($arrOccurence);
      $arrEnd = array_values($arrOccurence);
      array_shift($arrEnd);
  
      $i = 0;
      foreach($arrOccurence as $key => $start){
        $pointer = $start+strlen($key);
        if($i == count($arrEnd)){
          $arrOccurence[$key] = substr($string, $pointer);
        } else {
          $arrOccurence[$key] = substr($string, $pointer, $arrEnd[$i]-$pointer);
        } 
        $i++;
      }
      
    }
     //next part can be left apart if not necessary. In that case key that don't appear in the inputstringwill not be returned
    foreach($delimiters as $key => $value){
      if(!isset($arrOccurence[$value])){
        $arrOccurence[$value] = '';
      }
    }
    return $arrOccurence;
}
?>

I'm sure you guys get just a bit frustrated at times when you need a fraction of a very simple string and you use "explode()", but then you have to define a whole extra variable. (That is because you need to store a function-returned array in a variable before you can extract a value).
If you're extracting the last half, or third, of a string, there's an easy inline workaround. Check this:
<?php
 $mystr = "separated-text";
 print(str_replace("-","",strstr("-",$mystr)));
 //Returns "text"
?>
If the separator (dash) can be left in, you don't even need the "str_replace()" function.
Lets try this with 3 fractions:
<?php
 $mystr = "separated-text-again";
 //Comment submission wouldn't let me
 // combine this into one statement.
 // That's okay, it's more readable.
 $split1 = str_replace("-","",strstr("-",$mystr));
 print(str_replace("-","",strstr("-",$split1)));
 //Returns "again"
?>
Anything more than 3 fractions gets really confusing, in that case you should use "explode()".
Hope this helps!
~Cody G.

My application was running out of memory (my hosting company limits PHP to 32MB). I have a string containing between 100 and 20000 triplets, separated by a space, with each triplet consisting of three double-precision numbers, separated by commas. Total size of the biggest string, with 20000 triplets, is about 1MB.
The application needs to split the string into triplets, then split the triplet into numbers. In C, this would take up about 480K (20000 times 3 x 8 bytes) for the final array. The intermediate array of strings shouldn't be much bigger than the long string itself (1MB). And I expect some overhead from PHP, say 300% to allow for indexes etc.
Well, PHP5 manages to run out of memory *at the first stage* (exploding the string on the space character). I'm expecting to get an array of 20000 strings, but it needs more than 32MB to store it. Amazing.
The workaround was easy and had the bonus of producing faster code (I compared it on a 10000 triplet string). Since in any case I had to split up the numeric triplets afterwards, I decided to use preg_match_all() on the original string. Despite the fact that the resulting "matches" array contains more data per element than the result of explode() - because it stores the matched triplet, plus its component numbers - it takes up far less memory.
Moral: be careful when using explode() on big strings, as it can also explode your memory usage.

It should be said that when an empty delimiter is passed to explode, the function not only will return false but will also emit a warning.
<?php
var_dump( explode('','asdasd') );
/**
 * Output:
 * Warning: explode(): Empty delimiter in ...
 * bool(false)
 */
?>

As you can not send an enclosure value to explode, use str_getcsv,
if you want to explode a string when the delimiter is in some cells. (Comma in quotes)
<?php
 $a = "aaa1,bbb1,'ccc,ccc1',ddd1";
 $b = 'aaa2,bbb2,"ccc,ccc2",ddd2';
 // This dosn't work as it splits 'ccc,ccc1' and "ccc,ccc2".
 print "<PRE>a output using explode():\n";
 print_r( explode(",",$a) );
 print "</PRE>\n";
 print "<PRE>b output using explode():\n";
 print_r( explode(",",$b) );
 print "</PRE>\n";
 // This works.
 print "<PRE>a output using str_getcsv():\n";
 print_r( str_getcsv($a,",","'") );
 print "</PRE>\n";
 print "<PRE>b output using str_getcsv():\n";
 print_r( str_getcsv($b,",","\"") );
 print "</PRE>\n";
?>
explode() returns;
  [0] => aaa1
  [1] => bbb1
  [2] => 'ccc
  [3] => ccc1'
  [4] => ddd1
str_getcsv() returns;
  [0] => aaa1
  [1] => bbb1
  [2] => ccc,ccc1
  [3] => ddd1

A one-liner to extract a portion of a string, starting from the END of the string....
<?php
$extracted_string = implode('.', array_slice(explode('.', $original_string), -2));
?>

To split a string containing multiple seperators between elements rather use preg_split than explode:
preg_split ("/\s+/", "Here are  to  many spaces in  between");
which gives you
array ("Here", "are", "to", "many", "spaces", "in", "between");

If you want to have delimiter option as an array WITH limit option.
( an extended approach from php-at-metehanarslan-dot-com's )
<?php
/**
 * explode_multi function.
 *
 * Split a string by an array of string and limitable
 *
 * @access public
 * @param array  $delimiters
 * @param string  $string_raw
 * @param integer $limit (default: PHP_INT_MAX)
 * @return array
 */
function explode_multi($delimiters, $string_raw, $limit = PHP_INT_MAX)
{
  $string_tmp = (string) $string_raw;
  $string_rep = str_replace($delimiters, $delimiters[0], $string_raw);
  $exploded  = explode($delimiters[0], $string_rep, $limit);
  $result   = array();
  for ($key = 0; $key < ($limit-1); $key++) {
    $pattern  = $exploded[$key];
    $string_tmp = preg_replace("/${pattern}/", '', $string_tmp, 1);
    $result[]  = $pattern;
  }
  $result[] = trim($string_tmp);
  return $result;
}
?>

Sometimes I want to create a MINIMUM length array. For example, if the delimiter is not present at all, you might still want an empty additional item.
This can be done by adding the delimiter to the string as follows:
<?php
  $data='a';
  $array=explode(':',"$data:");
  print_r($array);
?>
If you want an EXACT number of elements, you can combine this with array_slice:
<?php
  $data='a:::';
  $array=explode(':',"$data:");
  $array=array_slice($array,0,2);  //  exactly 2 elements
  print_r($array);
?>

Note to the previous example: we can do the whole string->array conversion using explode() exclusively. 
<?php
  // converts pure string into a trimmed keyed array
  function string_2_array( $string, $delimiter = ',', $kv = '=>')
  {
    if ($element = explode( $delimiter, $string ))
    {
      // create parts
      foreach ( $element as $key_value )
      {
        // key -> value pair or single value
        $atom = explode( $kv, $key_value );
        if( trim($atom[1]) )
        {
         $key_arr[trim($atom[0])] = trim($atom[1]);
        }
        else
        {
          $key_arr[] = trim($atom[0]);
        }
      }
    }
    else
    {
      $key_arr = false;
    }
    return $key_arr;
  }
?>

Keep in mind that explode() can return empty elements if the delimiter is immediately repeated twice (or more), as shown by the following example:
<?php
$foo = 'uno dos tres'; // two spaces between "dos" and "tres"
print_r(explode(' ', $foo));
?>
Array
(
  [0] => uno
  [1] => dos
  [2] => 
  [3] => tres
)
Needless to say this is definitely not intuitive and must be handled carefully.

Note that while the documentation states the "If limit is set and positive," passing a null-value will still result in triggering the "limit is zero" case (as of PHP 5.4.17).
When passing through values (such as using explode to implement an interface method), you'll need to explicitly check that the limit has been set:
<?php
 public function split($string, $delimiter, $limit = null)
 {
  return isset($limit) ? explode($delimiter, $string, $limit) : explode($delimiter, $string);
 }
?>
Failing to check $limit and simply passing through a null-value will return the same value as if $limit were 0 or 1. To clarify, all of the following will return the same value:
<?php
explode($string, $delimiter, null);
explode($string, $delimiter, 0);
explode($string, $delimiter, 1);
?>

Note that explode, split, and functions like it, can accept more than a single character for the delimiter.
<?php
$string = "Something--next--something else--next--one more";
print_r(explode('--next--',$string));
?>

Note that using explode() on an empty string returns a non-empty array.
So the code:
<?php
 print_r(explode(" | ","");
?>
returns:
Array
(
  [0] => 
)
If you need to return an empty array in the case of an empty string, you must call array_diff() after the explode:
<?php
 print_r(array_diff(explode(" | ",""),array("")));
?>
returns:
Array
(
)
This is useful in case your use of MySQL's group_concat() returns an empty string for just some records but you want to convert them all to arrays that actually reflect what group_concat() gave you

If you need to split by multiple characters, use preg_split() instead:
  $new_string = preg_split("/[&=:]/", $string);

(excuse my english)
When I try to use explode to know if a string contains many words, I noticed this :
<?php
   $sentence= " word ";
   $array = explode($sentence); 
    var_dump($array);
?>
return this :
array(4) {
 [0]=> string(0) ""
 [1]=> string(0) ""
 [2]=> string(4) "word"
 [3]=> string(0) ""
}
So, "explode" didn't keep the delimiter but counts it. You have to use trim($sentence) to count words in a sentence. ^v^

That with all stateful encodings that use bytes between 0x00 and 0x7f for something other than, say, encoding ASCII characters. Including GBK, BIG5, Shift-JIS etc.
explode and other such PHP functions work on bytes, not characters.
What you do is to convert the string to UTF-8 using iconv(), then explode, then go back to GBK.

Simple function to explode a string with keys specified in the string.
<?php
function explode_with_keys($delim1,$delim2,$inputstring)
{
  $firstarr = explode($delim1,$inputstring);
  $finalarr = array();
  foreach($firstarr as $set)
  {
    $setarr = explode($delim2,$set);
    $finalarr[$setarr[0]] = $setarr[1];
  }
  return $finalarr;
}
print_r(explode_with_keys(";",":","a:b;c:d;e:f"));
?>
Will output:
Array ( [a] => b [c] => d [e] => f )

He found that the white girl's lame leg and chose to break up was actually broken up. If it weren’t for her pregnant with her children, he did not have a compound chance. When this opportunity arises, what he thinks is not Green Hat shame http://www.verobuddismo.ru/