array_slice()

(PHP 4, PHP 5, PHP 7)

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$offset和$length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。

$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。

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。

更新日志

范例

Example #1array_slice()例子

<?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));
?>

以上例程会输出：

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

参见

• array_splice() 去掉数组中的某一部分并用其它值取代
• unset() 释放给定的变量
• array_chunk() 将一个数组分割成多个

Array slice function that works with associative arrays (keys):
function array_slice_assoc($array,$keys) {
  return array_intersect_key($array,array_flip($keys));
}

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)

<?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;
}

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!

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.

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
)

To save the sort order of a numeric index in the array. Version php =>5.5.26
/*
Example
*/
$arr = array( "1" =>2, "2" =>3 , "3" =>5 );
print_r(array_slice($arr,1,null,true));
/*
Result
Array
(
[2] => 3
[3] => 5
)
*/

<?php
/**
 * @desc
 * Combines two arrays by inserting one into the other at a given position then
 * returns the result.
 *
 * @since  2007/10/04
 * @version v0.7 2007/10/04 18:47:52
 * @author AexChecker <AexChecker@yahoo.com>
 * @param  array $source
 * @param  array $destination
 * @param  int [optional] $offset
 * @param  int [optional] $length
 * @return array
 */
function array_insert($source, $destination, $offset = NULL, $length = NULL) {
  if (!is_array($source) || empty($source)) {
    if (is_array($destination) && !empty($destination)) {
      return $destination;
    }
    return array();
  }
  if (is_null($offset)) {
    return array_merge($destination, $source);
  }
  $offset = var2int($offset);
  if (is_null($length)) {
    if ($offset === 0) {
      return array_merge($source, array_slice($destination, 1));
    }
    if ($offset === -1) {
      return array_merge(array_slice($destination, 0, -1), $source);
    }
    return array_merge(
      array_slice($destination, 0, $offset),
      $source,
      array_slice($destination, ++$offset)
    );
  }
  if ($offset === 0) {
    return array_merge($source, array_slice($destination, $length));
  }
  $destination_count = count($destination);
  $length = var2int($length);
  if ($offset > 0) {
    if ($destination_count - $offset < 1) {
      return array_merge($destination, $source);
    }
  } else{
    if (($t = $destination_count + $offset) < 1) {
      return array_merge($source, $destination);
    }
    $offset = $t;
  }
  if ($length > 0) {
    $length+= $offset;
  } elseif ($length < 0 && !($length * -1 < $destination_count)) {
    return $source;
  } else {
    $length = $offset;
  }
  return array_merge(
    array_slice($destination, 0, $offset),
    $source,
    array_slice($destination, $length)
  );
}
?>

I was trying to find a good way to find the previous several and next several results from an array created in a MySQL query. I found that most MySQL solutions to this problem were complex. Here is a simple function that returns the previous and next rows from the array.
<?php
/*
** function array_surround by Jamon Holmgren of ClearSight Design
** Version 1.0 - 4/10/2009
** Please direct comments and questions to my first name at symbol clearsightdesign.com
**
** Returns an array with only the $before and $after number of results
** This is set to work best with MySQL data results
** Use this to find the rows immediately before and after a particular row, as many as you want
**
** Example usage:
**  $mysql_ar is an array of results from a MySQL query and the current id is $cur_id
**  We want to get the row before this one and five rows afterward
**
** $near_rows = array_surround($mysql_ar, "id", $cur_id, 1, 5)
**
**  Previous row is now $near_rows[-1]
**  Current row is now $near_rows[0]
**  Next row is $near_rows[1] ... etc
**  If there is no previous row, $near_rows[-1] will not be set...test for it with is_array($near_rows[-1])
**
*/
function array_surround($src_array, $field, $value, $before = 1, $after = 1) {
  if(is_array($src_array)) {
    // reset all the keys to 0 through whatever in case they aren't sequential
    $new_array = array_values($src_array);
    // now loop through and find the key in array that matches the criteria in $field and $value
    foreach($new_array as $k => $s) {
      if($s[$field] == $value) {
        // Found the one we wanted
        $ck = $k; // put the key in the $ck (current key)
        break;
      }
    }
    if(isset($ck)) { // Found it!
      $result_start = $ck - $before; // Set the start key
      $result_length = $before + 1 + $after; // Set the number of keys to return
      if($result_start < 0) { // Oops, start key is before first result
        $result_length = $result_length + $result_start; // Reduce the number of keys to return
        $result_start = 0; // Set the start key to the first result
      }
      $result_temp = array_slice($new_array, $result_start, $result_length); // Slice out the results we want
      // Now we have an array, but we want array[-$before] to array[$after] not 0 to whatever.
      foreach($result_temp as $rk => $rt) { // set all the keys to -$before to +$after
        $result[$result_start - $ck + $rk] = $rt;
      }
      return $result;
    } else { // didn't find it!
      return false;
    }
  } else { // They didn't send an array
    return false;
  }
}
?>
I hope you find this useful! I welcome constructive criticism or comments or of course praise ;) -- just e-mail me.
- Jamon Holmgren

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 
}

If you want to remove a specified entry from an array i made this mwethod...
<?php
$array = array("Entry1","entry2","entry3");
$int = 3; //Number of entries in the array
$int2 = 0; //Starter array spot... it will begine its search at 0.
$del_num = 1; //Represents the second entry in the array... which is the one we will happen to remove this time... i.e. 0 = first entry, 1 = second entry, 2 = third...........
$newarray = array(); //Empty array that will be the new array minus the specified entry...
print_r($array) . "<br>";  //print original array contents
print_r($newarray). "<br>"; //print the new empty array
do
{
$user = $array[$int2];
$key = array_search($user, $array);
if ($key == $del_num)
{
}
else
{
$newarray[] = $array[$int2];
}
$int2 = $int2 + 1;
} while ($int2 < $int);
print_r($newarray). "<br>"; //print the new array
?>

<?php
/**
 * Reorders an array by keys according to a list of values.
 * @param array $array the array to reorder. Passed by reference
 * @param array $list the list to reorder by
 * @param boolean $keepRest if set to FALSE, anything not in the $list array will be removed.
 * @param boolean $prepend if set to TRUE, will prepend the remaining values instead of appending them
 * @author xananax AT yelostudio DOT com
 */
function array_reorder(array &$array,array $list,$keepRest=TRUE,$prepend=FALSE,$preserveKeys=TRUE){
  $temp = array();
  foreach($list as $i){
    if(isset($array[$i])){
      $tempValue = array_slice(
        $array,
        array_search($i,array_keys($array)),
        1,
        $preserveKeys
      );
      $temp[$i] = array_shift($tempValue);
      unset($array[$i]);
    }
  }
  $array = $keepRest ?
    ($prepend? 
      $array+$temp
      :$temp+$array
    )
    : $temp;
}
/** exemple ** /
$a = array(
  'a'  =>  'a',
  'b'  =>  'b',
  'c'  =>  'c',
  'd'  =>  'd',
  'e'  =>  'e'
);
$order = array('c','b','a');
array_reorder($a,$order,TRUE);
echo '<pre>';
print_r($a);
echo '</pre>';
/** exemple end **/
?>

<?php
  // Combines two arrays by inserting one into the other at a given position then returns the result
  function array_insert($src, $dest, $pos) {
    if (!is_array($src) || !is_array($dest) || $pos <= 0) return FALSE;
    return array_merge(array_slice($dest, 0, $pos), $src, array_slice($dest, $pos));
  }
?>

just a little tip.
to preserve keys without providing length: use NULL
array_slice($array, $my_offset, NULL, true);

Note that offset is not the same thing as key. Offset always starts at 0, while keys might be any number.
So this:
<?php print_r(array_slice(array(0 => 0, 5 => 5, 13 => 13),1)); ?>
will result in this:
Array
(
  [0] => 5
  [1] => 13
)

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;
}
?>

/**
  * Remove a value from a array
  * @param string $val
  * @param array $arr
  * @return array $array_remval
  */
  function array_remval($val, &$arr)
  {
     $array_remval = $arr;
     for($x=0;$x<count($array_remval);$x++)
     {
       $i=array_search($val,$array_remval);
       if (is_numeric($i)) {
         $array_temp = array_slice($array_remval, 0, $i );
        $array_temp2 = array_slice($array_remval, $i+1, count($array_remval)-1 );
        $array_remval = array_merge($array_temp, $array_temp2);
       }
     }
     return $array_remval;
  }
$stack=Array('apple','banana','pear','apple', 'cherry', 'apple');
array_remval("apple", $stack);
//output: Array('banana','pear', 'cherry')

Thank to taylorbarstow here the function with the unset feature.
<?php
function array_slice_assoc(&$array,$keys,$unset = true) {
  $return = array_intersect_key($array, array_flip($keys));
  if ($unset) {
    foreach ($keys as $value) {
      unset($array[$value]);
    }
  }
  return $return;
}
?>

If you specify the fourth argument (to not reassign the keys), then there appears to be no way to get the function to return all values to the end of the array. Assigning -0 or NULL or just putting two commas in a row won't return any results.