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<array_shiftarray_splice>
Last updated: Thu, 19 May 2005

array_slice

(PHP 4, PHP 5)

array_slice -- Extract a slice of the array

Description

array array_slice ( array array, int offset [, int length [, bool preserve_keys]] )

array_slice() returns the sequence of elements from the array array as specified by the offset and length parameters.

If offset is non-negative, the sequence will start at that offset in the array. If offset is negative, the sequence will start that far from the end of the array.

If length is given and is positive, then the sequence will have that many elements in it. If length is given and is negative then the sequence will stop that many elements from the end of the array. If it is omitted, then the sequence will have everything from offset up until the end of the array.

Note that array_slice() will reset the array keys by default. Since PHP 5.0.2, you can change this behaviour by setting preserve_keys to TRUE.

Example 1. array_slice() examples

<?php
$input = array("a", "b", "c", "d", "e");

$output = array_slice($input, 2);      // returns "c", "d", and "e"
$output = array_slice($input, -2, 1);  // returns "d"
$output = array_slice($input, 0, 3);  // returns "a", "b", and "c"

// note the differences in the array keys
print_r(array_slice($input, 2, -1));
print_r(array_slice($input, 2, -1, true));
?>

The above example will output:

Array
(
    [0] => c
    [1] => d
)
Array
(
    [2] => c
    [3] => d
)

See also array_splice() and unset().



User Contributed Notes
array_slice
bishop
08-Dec-2004 03:58
Sometimes you need to pick certain non-integer and/or non-sequential keys out of an array. Consider using the array_pick() implementation below to pull specific keys, in a specific order, out of a source array:

<?php

$a = array ('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4);
$b = array_pick($a, array ('d', 'b'));

// now:
// $a = array ('a' => 1, 'c' => '3');
// $b = array ('d' => 4, 'b' => '2');

function &array_pick(&$array, $keys)
{
   if (! is_array($array)) {
       trigger_error('First parameter must be an array', E_USER_ERROR);
       return false;
   }

   if (! (is_array($keys) || is_scalar($keys))) {
       trigger_error('Second parameter must be an array of keys or a scalar key', E_USER_ERROR);
       return false;
   }

   if (is_array($keys)) {
       // nothing to do
   } else if (is_scalar($keys)) {
       $keys = array ($keys);
   }

   $resultArray = array ();
   foreach ($keys as $key) {
       if (is_scalar($key)) {
           if (array_key_exists($key, $array)) {
               $resultArray[$key] = $array[$key];
               unset($array[$key]);
           }
       } else {
           trigger_error('Supplied key is not scalar', E_USER_ERROR);
           return false;
       }
   }

   return $resultArray;
}

?>
pies at sputnik dot pl
17-Sep-2004 11:29
My shot at Dams's array_slice_key() implementation:

function array_slice_key($array, $offset, $len=-1){

   if (!is_array($array))
       return FALSE;

   $length = $len >= 0? $len: count($array);
   $keys = array_slice(array_keys($array), $offset, $length);
   foreach($keys as $key) {
       $return[$key] = $array[$key];
   }
 
   return $return;
}
Samuele at norsam dot org
05-Apr-2004 11:44
Note that if $offset+$length>count($array) then resulting array will NOT be filled with empty elements at his end, so it is not sure that it will have exactly $length elements. Example:
<?php
$a=Array(7,32,11,24,65); // count($a) is 5
$b=array_slice($a,2,4);  // 2+4=6, and 6>count($a)
print_r($b);
?>
will return a 3-elements array:
  Array
  (
     [0] => 11
     [1] => 24
     [2] => 65
  )
23-Feb-2004 04:47
Use unset() to delete a associative array.

Ex:
<?php
                                                                                                                              
$item['chaise'] = array ('qty' => 1,
                       'desc' => 'Chaise bercante 10"',
                       'avail' => 10);
                                                                                                                              
$item['divan'] = array ('qty' => 1,
                       'desc' => 'Divan brun laitte"',
                       'avail' => 10);
                                                                                                                              
if (isset($item['chaise'])) {
       ++$item['chaise']['qty'];
       }
                                                                                                                              
unset($item['divan']);
                                                                                                                              
foreach ($item as $s) {
       echo "<br />Commande " . $s['qty'] . " " . $s['desc'];
}
                                                                                                                              
?>
jenny at jennys dot info
22-Feb-2004 12:12
Here's a function which returns the array offset based on the array key.  This is useful if you'd like to use array_slice to get all keys/values after key "foo".

<?
function array_offset($array, $offset_key) {
  $offset = 0;
  foreach($array as $key=>$val) {
   if($key == $offset_key)
     return $offset;
   $offset++;
  }
  return -1;
}

$array = array('foo'=>'foo', 'bar'=>'bar', 'bash'=>'bash', 'quux'=>'quux');
print_r($array);
// Prints the following:
// Array
// (
//    [foo] => foo
//    [bar] => bar
//    [bash] => bash
//    [quux] => quux
// )

$offset = array_offset($array,'bar');
// $offset now contains '1'
$new = array_slice($array,$offset+1);
print_r($new);
// Prints the following:
// Array
// (
//    [bash] => bash
//    [quux] => quux
// )
?>
webmaster_nospam at wavesport dot com
12-Nov-2002 06:48
This function may surprise you if you use arbitrary numeric values for keys, i.e.

<?php
//create an array
$ar = array('a'=>'apple', 'b'=>'banana', '42'=>'pear', 'd'=>'orange');

print_r($ar);
// print_r describes the array as:
// Array
// (
//    [a] => apple
//    [b] => banana
//    [42] => pear
//    [d] => orange
// )

//use array_slice() to extract the first three elements
$new_ar = array_slice($ar, 0, 3);

print_r($new_ar);
// print_r describes the new array as:
// Array
// (
//    [a] => apple
//    [b] => banana
//    [0] => pear
// )
?>

The value 'pear' has had its key reassigned from '42' to '0'.

When $ar is initially created the string '42' is automatically type-converted by array() into an integer.  array_slice() and array_splice() reassociate string keys from the passed array to their values in the returned array but numeric keys are reindexed starting with 0.
t dot oddy at ic dot ac dot uk
25-Apr-2002 08:47
[Editor's Note:
It is easier to do the same thing using array_values()
]
array_slice() can be used to "re-index" an array to start from key 0.  For example, unpack creates an array with keys starting from 1;

<?php
var_dump(unpack("C*","AB"));
?>

produces

<?php
array(2) {
  [1]=>
  int(65)
  [2]=>
  int(66)
}
?>

and

<?php
var_dump(array_slice(unpack("C*","AB"),0));
?>

give you

<?php
array(2) {
  [0]=>
  int(65)
  [1]=>
  int(66)
}
?>
developer at i-space dot org
03-Feb-2002 10:22
remember that array_slice returns an array with the current element. you must use array_slice($array, $index+1) if you want to get the next elements.
richardgere at jippii dot fi
27-Jan-2002 11:14
The same thing, written by a maladroit :)

<?php
function array_slice2( $array, $offset, $length = 0 )
{
  if( $offset < 0 )
   $offset = sizeof( $array ) + $offset;

  $length = ( !$length ? sizeof( $array ) : ( $length < 0 ? sizeof( $array ) - $length : $length + $offset ) );

  for( $i = $offset; $i < $length; $i++ )
   $tmp[] = $array[$i];

  return $tmp;     
}
?>
dams at php dot net
15-Dec-2001 09:09
Here is a version of Array_slice which takes into account keys.

That may be a suggestion for future developpement.

<?php
function array_slice_key($array, $offset){
  if (!is_array($array))
     return FALSE;
    
  if (func_num_args() == 3){
   $length = func_get_arg(2);
   $length = max(0,intval($length));
  } else {
   $length = count($array);
  }
 
  $i = 0;
  $return = array();
  $keys = array_slice(array_keys($array), $offset, $length);
  foreach( $keys as $key){
   $return[$key] = $array[$key];
  }
  return $return;
}
?>

<array_shiftarray_splice>
 Last updated: Thu, 19 May 2005
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Last updated: Thu May 19 17:35:34 2005 CDT