array_slice

add a note User Contributed Notes

ps at b1g dot de
04-Nov-2006 06:44


The following function is the same as array_slice with preserve_keys=true, but it works with PHP versions < 5.0.2.

When PHP >= 5.0.2 is available, the function uses the faster PHP-own array_slice-function with preserve_keys=true, otherwise it uses its own  implementation.



<?php

/**

 * array_slice with preserve_keys for every php version

 *

 * @param array $array Input array

 * @param int $offset Start offset

 * @param int $length Length

 * @return array

 */

function array_slice_preserve_keys($array, $offset, $length = null)

{

    // PHP >= 5.0.2 is able to do this itself

    if((int)str_replace('.', '', phpversion()) >= 502)

        return(array_slice($array, $offset, $length, true));



    // prepare input variables

    $result = array();

    $i = 0;

    if($offset < 0)

        $offset = count($array) + $offset;

    if($length > 0)

        $endOffset = $offset + $length;

    else if($length < 0)

        $endOffset = count($array) + $length;

    else

        $endOffset = count($array);

    

    // collect elements

    foreach($array as $key=>$value)

    {

        if($i >= $offset && $i < $endOffset)

            $result[$key] = $value;

        $i++;

    }

    

    // return

    return($result);

}

?>



Good for backwards compatibility I hope somebody might find this useful.

david at bagnara dot org
19-Oct-2006 11:42


I was trying to pass an argument list through the constructors. I tried various things such as func_get_args(). My conclusion is to pass the args to the constructor as an array. Each constructor can remove the fields it wants and pass the array on.



Using the following prototype, each child class can have any number of parameters added to the beginning of the class constructor and the rest passed onto the parent.



If the default value is desired for an argument, just pass NULL.



This could possibly be better done with array_shift or the like.



<?php



class aChild extends aParent

{

    // TODO customise this list for this class

    public

        $a, $b, $c;



    function __construct( $args = array() )

    {

        //set up default values for this class

        // TODO customise this list for this class

        $default = array( "a-def", "b-def", "c-def" ) ;

        // now overwrite the default with non NULL args

        foreach( $args as $key=>$val )

        {

            // more args than needed?

            if( !isset( $default[$key] ) )

            {

                break;

            }

            // this arg not null

            if( isset( $val ) )

            {

                $default[$key] = $val ;

            }

        }

        // set this to the new values

        // TODO customise this list for this class

        list( $this->a, $this->b, $this->c ) = $default ;

        // take off the ones we used

        $args = array_slice( $args, count( $default ) ) ;

        parent::__construct( $args ) ;

    }

}



$x = new aChild( array( "aChild a", NULL, "aChild c", NULL, "aParent second", "aParent third" ) ) ;

?>

DRB
25-Aug-2006 04:08


In response to the problem mentioned in the previous post (no name 06-May-2006 12:21) the following is a working solution:



$myarray = array_slice($myarray, 1, count($myarray), true);



It is too bad that the "preserve_keys" option is not available for the array_shift and array_pop functions as this would be somewhat simpler.

06-May-2006 03:21


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.

taylorbarstow at the google mail service
08-Apr-2006 05:01


Array slice function that works with associative arrays (keys):



function array_slice_assoc($array,$keys) {

    return array_intersect_key($array,array_flip($keys));

}

andreasblixt (at) msn (dot) com
07-Sep-2005 12:53


<?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));

    }

?>

ssb45 at cornell dot edu
28-Jul-2005 10:20


In reply to jenny at jennys dot info:



Here is a much easier way to find the $offset of a $key in an $array:



$offset = array_search($key, array_keys($array));

fanfatal at fanfatal dot pl
09-Jul-2005 06:09


Hmm ... i wrote an usefull function whitch is such like strpos but it works on arrays ;]



<?php

/*

 *    Find position of first occurrence of a array 

 *

 *    @param array $haystack

 *    @param array $needle

 *    @return int

 *    @author FanFataL

 */

function array_pos($haystack, $needle) {

    $size = count($needle);

    $sizeh = count($haystack);

    if($size > $sizeh) return false;



    $scale = $sizeh - $size + 1;



    for($i = 0; $i < $scale; $i++)

        if($needle === array_slice($haystack, $i, $size))

            return $i;



    return false;

}



// Sample:

$a = array('aa','bb','cc','dd','ee');

$b = array('cc','dd');

$pos = array_pos($a, $b);

?>



Greatings ;-)

...

david dot tulloh at infaze dot com dot au
24-Jun-2005 09:26


Nice one liner to extract a column from a 2D array.

It works by using array_slice on every row, through array_map.



<?php

// set up a small test environment

$test_subject[] = array("a", "b", "c");

$test_subject[] = array("d", "e", "f");



$column=1;



// do the actual work

$result = array_map('array_slice', $test_subject,

    array_fill(0, count($test_subject), $column),

    array_fill(0, count($test_subject), 1)

);



// and the end result

result == array ( array("b"), array("e") );

?>

liz at matrixmailing dot com
07-Jun-2005 05:16


For those with PHP < 5.0.2, and have a number as your array key, to avoid having the key reset with array_slice, add a blank character to the beginning or end of the key.

<?



$array[" ".$key] = $value;



?>

bishop
09-Dec-2004 05:58


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
18-Sep-2004 12:29


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
06-Apr-2004 12:44


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

  )

24-Feb-2004 06:47


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 02:12


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
13-Nov-2002 08:48


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 09:47


[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
04-Feb-2002 12:22


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
28-Jan-2002 01:14


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
16-Dec-2001 11:09


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;


}


?>

add a note

array_slice

说明