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array_slice

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

array_slice从数组中取出一段

说明

array_slice(
    array $array,
    int $offset,
    ?int $length = null,
    bool $preserve_keys = false
): array

array_slice() 返回根据 offsetlength 参数所指定的 array 数组中的一段序列。

参数

array

输入的数组。

offset

如果 offset 非负,则序列将从 array 中的此偏移量开始。

如果 offset 为负,则序列将从 array 中距离末端这么远的地方开始。

注意:

参数 offset 标识的是数组中的位置,而不是键。

length

如果给出了 length 并且为正,则序列中将具有这么多的单元。

如果 array 比 length 要短,只会保留有效的数组单元。

如果给出了 length 并且为负,则序列将终止在距离数组末端这么远的地方。

如果省略,则序列将从 offset 开始一直到 array 的末端。

preserve_keys

注意:

注意 array_slice() 默认会重新排序并重置数组的数字索引。你可以通过将 preserve_keys 设为 true 来改变此行为。 无论本参数如何设置,都会保留字符串的键。

返回值

返回其中一段。 如果 offset 参数大于 array 尺寸,就会返回空的 array。

示例

示例 #1 array_slice() 例子

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

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

// 注意数组中 key 的不同
print_r(array_slice($input, 2, -1));
print_r(array_slice($input, 2, -1, true));
?>

以上示例会输出:

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

示例 #2 array_slice() 于索引从 1 开始的 array

<?php
$input
= array(1 => "a", "b", "c", "d", "e");
print_r(array_slice($input, 1, 2));
?>

以上示例会输出:

Array
(
    [0] => b
    [1] => c
)

示例 #3 array_slice() 与混合类型键的 array

<?php
$ar
= array('a'=>'apple', 'b'=>'banana', '42'=>'pear', 'd'=>'orange');
print_r(array_slice($ar, 0, 3));
print_r(array_slice($ar, 0, 3, true));
?>

以上示例会输出:

Array
(
    [a] => apple
    [b] => banana
    [0] => pear
)
Array
(
    [a] => apple
    [b] => banana
    [42] => pear
)

参见

添加备注

用户贡献的备注 8 notes

up
51
taylorbarstow at the google mail service
19 years ago
Array slice function that works with associative arrays (keys):

function array_slice_assoc($array,$keys) {
    return array_intersect_key($array,array_flip($keys));
}
up
19
Ray.Paseur often uses Gmail
12 years ago
<?php
// CHOP $num ELEMENTS OFF THE FRONT OF AN ARRAY
// RETURN THE CHOP, SHORTENING THE SUBJECT ARRAY
function array_chop(&$arr, $num)
{
    $ret = array_slice($arr, 0, $num);
    $arr = array_slice($arr, $num);
    return $ret;
}
up
7
nathan dot fiscaletti at gmail dot com
8 years ago
If you want an associative version of this you can do the following:

function array_slice_assoc($array,$keys) {
    return array_intersect_key($array,array_flip($keys));
}

However, if you want an inverse associative version of this, just use array_diff_key instead of array_intersect_key. 

function array_slice_assoc_inverse($array,$keys) {
    return array_diff_key($array,array_flip($keys));
}

Example:

$arr = [
    'name' => 'Nathan',
    'age' => 20,
    'height' => 6
];

array_slice_assoc($arr, ['name','age']);

will return 

Array (
     'name' = 'Nathan',
     'age' = 20
)

Where as

array_slice_assoc_inverse($arr, ['name']);

will return 

Array (
    'age' = 20,
    'height' = 6
)
up
4
ted.devito at 9gmail9 dot 99com
17 years ago
based on worldclimb's arem(), here is a recursive array value removal tool that can work with multidimensional arrays.

function remove_from_array($array,$value){
    $clear = true;
    $holding=array();
   
    foreach($array as $k => $v){
        if (is_array($v)) {
            $holding [$k] = remove_from_array ($v, $value);
            }
        elseif ($value == $v) {
            $clear = false;
            }
        elseif($value != $v){
            $holding[$k]=$v; // removes an item by combing through the array in order and saving the good stuff
        }
    }   
    if ($clear) return $holding; // only pass back the holding array if we didn't find the value 
}
up
11
worldclimb at 99gmail99 dot com
17 years ago
array_slice can be used to remove elements from an array but it's pretty simple to use a custom function.

One day array_remove() might become part of PHP and will likely be a reserved function name, hence the unobvious choice for this function's names.

<?
function arem($array,$value){
    $holding=array();
    foreach($array as $k => $v){
        if($value!=$v){
            $holding[$k]=$v;
        }
    }    
    return $holding;
}

function akrem($array,$key){
    $holding=array();
    foreach($array as $k => $v){
        if($key!=$k){
            $holding[$k]=$v;
        }
    }    
    return $holding;
}

$lunch = array('sandwich' => 'cheese', 'cookie'=>'oatmeal','drink' => 'tea','fruit' => 'apple');
echo '<pre>';
print_r($lunch);
$lunch=arem($lunch,'apple');
print_r($lunch);
$lunch=akrem($lunch,'sandwich');
print_r($lunch);
echo '</pre>';
?>

(remove 9's in email)
up
2
Benjamin Sonntag
2 years ago
The documentation doesn't say it, but if LENGTH is ZERO, then the result is an empty array [].
up
8
developer at i-space dot org
23 years ago
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.
up
5
s0i0m at dreamevilconcepts dot com
17 years ago
Using the varname function referenced from the array_search page, submitted by dcez at land dot ru. I created a multi-dimensional array splice function. It's usage is like so:

$array['admin'] = array('blah1', 'blah2');
$array['voice'] = array('blah3', 'blah4');
array_cut('blah4', $array);

...Would strip blah4 from the array, no matter where the position of it was in the array ^^ Returning this...

Array ( [admin] => Array ( [0] => blah1 [1] => blah2 ) [voice] => Array ( [0] => blah3 ) ) 

Here is the code...

<?php

  function varname ($var)
  {
    // varname function by dcez at land dot ru
    return (isset($var)) ? array_search($var, $GLOBALS) : false;
  }

  function array_cut($needle, $haystack)
  {
    foreach ($haystack as $k => $v)
    {
      for ($i=0; $i<count($v); $i++)
        if ($v[$i] === $needle)
        {
          return array_splice($GLOBALS[varname($haystack)][$k], $i, 1);
          break; break;
        }
    }

?>

Check out dreamevilconcept's forum for more innovative creations!
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