array_splice

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

array_splice — Remove a portion of the array and replace it with something else

Description

array_splice(
    array &$array,
    int $offset,
    ?int $length = null,
    mixed $replacement = []
): array

Removes the elements designated by offset and length from the array array, and replaces them with the elements of the replacement array, if supplied.

Note:
Numerical keys in array are not preserved.

Note: If replacement is not an array, it will be typecast to one (i.e. (array) $replacement). This may result in unexpected behavior when using an object or null replacement.

Parameters

array

The input array.

offset

If offset is positive then the start of the removed portion is at that offset from the beginning of the array array.

If offset is negative then the start of the removed portion is at that offset from the end of the array array.

length

If length is omitted, removes everything from offset to the end of the array.

If length is specified and is positive, then that many elements will be removed.

If length is specified and is negative, then the end of the removed portion will be that many elements from the end of the array.

If length is specified and is zero, no elements will be removed.

Tip

To remove everything from offset to the end of the array when replacement is also specified, use count($input) for length.

replacement

If replacement array is specified, then the removed elements are replaced with elements from this array.

If offset and length are such that nothing is removed, then the elements from the replacement array are inserted in the place specified by the offset.

Note:
Keys in the replacement array are not preserved.

If replacement is just one element it is not necessary to put array() or square brackets around it, unless the element is an array itself, an object or null.

Return Values

Returns an array consisting of the extracted elements.

Changelog

Version	Description
8.0.0	`length` is nullable now.

Examples

Example #1 array_splice() examples

<?php
$input = array("red", "green", "blue", "yellow");
array_splice($input, 2);
var_dump($input);

$input = array("red", "green", "blue", "yellow");
array_splice($input, 1, -1);
var_dump($input);

$input = array("red", "green", "blue", "yellow");
array_splice($input, 1, count($input), "orange");
var_dump($input);

$input = array("red", "green", "blue", "yellow");
array_splice($input, -1, 1, array("black", "maroon"));
var_dump($input);
?>

The above example will output:

array(2) {
  [0]=>
  string(3) "red"
  [1]=>
  string(5) "green"
}
array(2) {
  [0]=>
  string(3) "red"
  [1]=>
  string(6) "yellow"
}
array(2) {
  [0]=>
  string(3) "red"
  [1]=>
  string(6) "orange"
}
array(5) {
  [0]=>
  string(3) "red"
  [1]=>
  string(5) "green"
  [2]=>
  string(4) "blue"
  [3]=>
  string(5) "black"
  [4]=>
  string(6) "maroon"
}

Example #2 Equivalent statements to various array_splice() examples

The following statements are equivalent:

<?php

// append two elements to $input
array_push($input, $x, $y);
array_splice($input, count($input), 0, array($x, $y));

// remove the last element of $input
array_pop($input);
array_splice($input, -1);

// remove the first element of $input
array_shift($input);
array_splice($input, 0, 1);

// insert an element at the start of $input
array_unshift($input, $x, $y);
array_splice($input, 0, 0, array($x, $y));

// replace the value in $input at index $x
$input[$x] = $y; // for arrays where key equals offset
array_splice($input, $x, 1, $y);

?>

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User Contributed Notes 38 notes

down

mrsohailkhan at gmail dot com ¶

12 years ago

array_splice, split an array into 2 arrays. The returned arrays is the 2nd argument actually and the used array e.g $input here contains the 1st argument of array, e.g


<?php

$input = array("red", "green", "blue", "yellow");

print_r(array_splice($input, 3)); // Array ( [0] => yellow )  

print_r($input); //Array ( [0] => red [1] => green [2] => blue )

?>



if you want to replace any array value do simple like that,


first search the array index you want to replace


<?php $index = array_search('green', $input);// index = 1 ?>



and then use it as according to the definition


<?php

array_splice($input, $index, 1, array('mygreeen')); //Array ( [0] => red [1] => mygreeen [2] => blue [3] => yellow ) 

?>



so here green is replaced by mygreen.


here 1 in array_splice above represent the number of items to be replaced. so here start at index '1' and replaced only one item which is 'green'

down

royanee at yahoo dot com ¶

11 years ago

When trying to splice an associative array into another, array_splice is missing two key ingredients:
  - a string key for identifying the offset
  - the ability to preserve keys in the replacement array

This is primarily useful when you want to replace an item in an array with another item, but want to maintain the ordering of the array without rebuilding the array one entry at a time.

<?php
function array_splice_assoc(&$input, $offset, $length, $replacement) {
$replacement = (array) $replacement;
$key_indices = array_flip(array_keys($input));
        if (isset($input[$offset]) && is_string($offset)) {
$offset = $key_indices[$offset];
        }
        if (isset($input[$length]) && is_string($length)) {
$length = $key_indices[$length] - $offset;
        }

$input = array_slice($input, 0, $offset, TRUE)
                + $replacement
+ array_slice($input, $offset + $length, NULL, TRUE);
}

$fruit = array(
'orange' => 'orange',
'lemon' => 'yellow',
'lime' => 'green',
'grape' => 'purple',
'cherry' => 'red',
);

// Replace lemon and lime with apple
array_splice_assoc($fruit, 'lemon', 'grape', array('apple' => 'red'));

// Replace cherry with strawberry
array_splice_assoc($fruit, 'cherry', 1, array('strawberry' => 'red'));
?>

Note: I have not tested this with negative offsets and lengths.

down

StanE ¶

8 years ago

array_splice() does not preserve numeric keys. The function posted by "weikard at gmx dot de" won't do that either because array_merge() does not preserve numeric keys either.

Use following function instead:

<?php
function arrayInsert($array, $position, $insertArray)
{
$ret = [];

    if ($position == count($array)) {
$ret = $array + $insertArray;
    }
    else {
$i = 0;
        foreach ($array as $key => $value) {
            if ($position == $i++) {
$ret += $insertArray;
            }

$ret[$key] = $value;
        }
    }

    return $ret;
}
?>

Example:
<?php
$a = [
295 => "Hello",
58 => "world",
];

$a = arrayInsert($a, 1, [123 => "little"]);

/*
Output:
Array
(
    [295] => Hello
    [123] => little
    [58] => world
)
*/
?>

It preserves numeric keys. Note that the function does not use a reference to the original array but returns a new array (I see absolutely no reason how the performance would be increased by using a reference when modifying an array through PHP script code).

down

daniele centamore ¶

15 years ago

just useful functions to move an element using array_splice.

<?php

// info at danielecentamore dot com

// $input  (Array) - the array containing the element
// $index (int) - the index of the element you need to move

function moveUp($input,$index) {
$new_array = $input;

       if((count($new_array)>$index) && ($index>0)){
array_splice($new_array, $index-1, 0, $input[$index]);
array_splice($new_array, $index+1, 1);
             } 

       return $new_array;
}

function moveDown($input,$index) {
$new_array = $input;

       if(count($new_array)>$index) {
array_splice($new_array, $index+2, 0, $input[$index]);
array_splice($new_array, $index, 1);
             } 

       return $new_array;
 }  

$input = array("red", "green", "blue", "yellow");

$newinput = moveUp($input, 2);
// $newinput is array("red", "blue", "green", "yellow")

$input = moveDown($newinput, 1);
// $input is array("red", "green", "blue", "yellow")

?>

down

charette dot s at gmail ¶

14 years ago

If you want to append null values wrap them in an array:

<?php

    $a = array('Hey', 'hey', 'my', 'my');
array_splice($a, 1, 0, null);
print_r($a);

?>
Array
(
    [0] => Hey
    [1] => hey
    [2] => my
    [3] => my
)

<?php

    $b = array('Hey', 'hey', 'my', 'my');
array_splice($b, 1, 0, array(null));
print_r($b);

?>
Array
(
    [0] => Hey
    [1] => 
    [2] => hey
    [3] => my
    [4] => my
)

down

gideon at i6developments dot com ¶

20 years ago

array_splice dynamically updates the total number of entries into the array. So for instance I had a case where I needed to insert a value into every 4th entry of the array from the back. The problem was when it added the first, because the total number was dynamically updated, it would only add after the 3rd then the 2nd and so one. The solution I found is to track the number of inserts which were done and account for them dynamically. 

Code: 
<?php
    $modarray = array_reverse($mili);
$trig=1;
        foreach($modarray as $rubber => $glue) {
            if($rubber!="<BR>") {
$i++;
$b++;
            if ($i==4) {
$trig++;
                if($trig<=2) {
array_splice($modarray,$b,0,"<BR>");
                }elseif($trig>=3){
array_splice($modarray,$b+($trig-2),0,"<BR>");
                } 
$i=0;
                };
                };
        };    
$fixarray = array_reverse($modarray);

?>

down

weikard at gmx dot de ¶

18 years ago

You cannot insert with array_splice an array with your own key. array_splice will always insert it with the key "0".


<?php

// [DATA]

$test_array = array (

row1 => array (col1 => 'foobar!', col2 => 'foobar!'),

row2 => array (col1 => 'foobar!', col2 => 'foobar!'),

row3 => array (col1 => 'foobar!', col2 => 'foobar!')

);


// [ACTION]

array_splice ($test_array, 2, 0, array ('rowX' => array ('colX' => 'foobar2')));

echo '<pre>'; print_r ($test_array); echo '</pre>';

?>



[RESULT]


Array (

    [row1] => Array (

            [col1] => foobar!

            [col2] => foobar!

        )


    [row2] => Array (

            [col1] => foobar!

            [col2] => foobar!

        )


    [0] => Array (

            [colX] => foobar2

        )


    [row3] => Array (

            [col1] => foobar!

            [col2] => foobar!

        )

)


But you can use the following function:


function array_insert (&$array, $position, $insert_array) {

  $first_array = array_splice ($array, 0, $position);

  $array = array_merge ($first_array, $insert_array, $array);

}


<?php

// [ACTION]


array_insert ($test_array, 2, array ('rowX' => array ('colX' => 'foobar2')));

echo '<pre>'; print_r ($test_array); echo '</pre>';

?>



[RESULT]


Array (

    [row1] => Array (

            [col1] => foobar!

            [col2] => foobar!

        )


    [row2] => Array (

            [col1] => foobar!

            [col2] => foobar!

        )


    [rowX] => Array (

            [colX] => foobar2

        )


    [row3] => Array (

            [col1] => foobar!

            [col2] => foobar!

        )

)


[NOTE]


The position "0" will insert the array in the first position (like array_shift). If you try a position higher than the langth of the array, you add it to the array like the function array_push.

down

plintus at smtp dot ru ¶

21 years ago

key-safe:


<?php

function array_kslice ($array, $offset, $length = 0) {

$k = array_slice (array_keys ($array), $offset, $length);

$v = array_slice (array_values ($array), $offset, $length);

for ($i = 0; $i < count ($k); $i ++) $r[$k[$i]] = $v[$i];

return $r;

}

?>



smth like this. hope you like it more than versions above :)

down

gilberg_vrn ¶

8 years ago

array_splice with preserve keys

<?php
function array_splice_preserve_keys(&$array, $from, $length = null) {
$result = array_slice($array, $from, $length, true);
$array = array_slice($array, $from + $length, null, true);

    return $result;
}
?>

Example:

<?php
$array = [
1 => 'a',
2 => 'b',
26 => 'z'
];

var_dump(array_splice_preserve_keys($array, 0, 1), $array);
/**
 * array(1) {
 *  [1]=>
 *   string(1) "a"
 *  }
 * array(2) {
 *  [2]=>
 *  string(1) "b"
 *  [26]=>
 *  string(1) "z"
 * }
 */
?>

down

guillaume dot lacourt at gmail dot com ¶

9 years ago

Using array_splice when you traverse array with internal pointer's function reset the array, eg:

<?php
end($arrOfData);
$last = key($arrOfData);
reset($arrOfData);
while (($data = current($arrOfData))) {
  if ($last === key($arrOfData)) {
array_splice($arrOfData, $last, 1);
// current($arrOfData) => first value of $arrOfData
}
}

down

csaba at alum dot mit dot edu ¶

19 years ago

Appending arrays

If you have an array $a2 whose values you would like to append to an array $a1 then four methods you could use are listed below in order of increasing time.  The last two methods took significantly more time than the first two.  The most surprising lesson is that using the & incurs a time hit.


<?php

foreach ($a2 as $elem) $a1[]=$elem;

foreach ($a2 as &$elem) $a1[]=$elem;

array_splice ($a1, count($a1), 0, $a2);

$a1 = array_merge($a1, $a2);

?>



Csaba Gabor from Vienna

down

thom ¶

10 years ago

Maybe it will help someone else: I was trying to strip off the last part of an array using this section, more or less as follows:

<?php array_splice($array, $offset); ?>

Now it could occur in my code that <?php $offset === 0 ?>, in which case the array is returned as-is and not, as you might expect, an empty array because everything is stripped off. Obviously it is not really useful anyway to "strip off everything", but I was reminded of that the hard way and this may spare someone some time, hopefully.

down

kbrown at horizon dot sk dot ca ¶

21 years ago

[ Editor's Note: If you're not concerned with the indexes being contiguously numbered (such as for an associative array) then unset($ar[$ind]); will accomplish the same as the code below without requiring splice/splice/merge.  If contiguous numbering IS a concern (such as for indexed arrays), you can still save time by using: unset($ar[$ind]); $ar = array_values($ar); ]


Removing elements from arrays


This works better - much quicker


<?php

$ar = array("einstein", "bert", "colin", "descartes", "renoir");

$a = array_slice($ar, 0, $ind);

$b = array_slice($ar, $ind + 1);

$ar = array_merge($a, $b);

?>

down

news_yodpeirs at thoftware dot de ¶

14 years ago

Splicing with NULL as replacement may result in unexpected behavior too. Typecasting NULL into an array results in an empty array (as "(array)NULL" equals "array()"). That means, instead of creating an element with value NULL just no new element ist created (just as if there was no replacement specified).

If you want the splicing to create a new element with value NULL you have to use "array(NULL)" instead of NULL.

You should expect this if you read the explanation carefully, but just as objects are considered as a special case for replacement, NULL should be too.

The explanation of replacement better should read: "If replacement is just one element it is not necessary to put array() around it, unless the element is an array itself, an object or NULL."

And the note better should be: "If replacement is not an array, it will be typecast to one (i.e. (array) $parameter). This may result in unexpected behavior when using an object or NULL replacement."

jmtc

down

jrhardytwothousandtwo at yahoo dot com ¶

22 years ago

A reference is made to INSERT'ing into an array here with array_splice, however its not explained very well.  I hope this example will help others find what took me days to research.


<?php

$original_array = array(1,2,3,4,5);

$insert_into_key_position = 3;

$item_to_insert = "blue";


$returned = array_splice($original_array, $insert_into_key_position, 0, $item_to_insert);


// $original_array will now show:


// 1,2,3,blue,4,5

?>



Remember that you are telling the array to insert the element into the KEY position.  Thus the elements start with key 0 and so on 0=>1, 1=>2, 2=>3, 3=>blue, 4=>4, 5=>5.  And walla, you've inserted.  I can't say if this is of any value for named keys, or multidimensional arrays.  However it does work for single dimensional arrays.


$returned should be an empty array as nothing was returned.  This would have substance if you were doing a replace instead.

down

pauljamescampbell at gmail dot com ¶

16 years ago

Here's my own take on an array slice method that preserves keys from an associative array.


<?php

/**

 * Array slice function that preserves associative keys

 * 

 * @function associativeArraySlice

 *

 * @param  Array  $array  Array to slice

 * @param  Integer  $start    

 * @param  Integer  $end

 * 

 * @return  Array

 */

function associativeArraySlice($array, $start, $end) {

// Method param restrictions

if($start < 0) $start = 0;

    if($end > count($array)) $end = count($array);


// Process vars

$new = Array();

$i = 0;


// Loop

foreach($array as $key => $value) {

        if($i >= $start && $i < $end) {

$new[$key] = $value;

        }

$i++;

    }

    return($new);

}

?>

down

randomdestination at gmail dot com ¶

19 years ago

To split an associative array based on it's keys, use this function:

<?php
function &array_split(&$in) {
$keys = func_get_args();
array_shift($keys);

$out = array();
    foreach($keys as $key) {
        if(isset($in[$key]))
$out[$key] = $in[$key];
        else
$out[$key] = null;
        unset($in[$key]);
    }

    return $out;
}
?>

Example: 
<?php
$testin = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4);
$testout =& array_split($testin, 'a', 'b', 'c');

print_r($testin);
print_r($testout);
?>

Will print:

Array
(
    [d] => 4
)
Array
(
    [a] => 1
    [b] => 2
    [c] => 3
)

Hope this helps anyone!

down

ahigerd at stratitec dot com ¶

17 years ago

A comment on array_merge mentioned that array_splice is faster than array_merge for inserting values. This may be the case, but if your goal is instead to reindex a numeric array, array_values() is the function of choice. Performing the following functions in a 100,000-iteration loop gave me the following times: ($b is a 3-element array)

array_splice($b, count($b)) => 0.410652
$b = array_splice($b, 0) => 0.272513
array_splice($b, 3) => 0.26529
$b = array_merge($b) => 0.233582
$b = array_values($b) => 0.151298

down

mip at ycn dot com ¶

17 years ago

Ever wounder what array_splice is doing to your references, then try this little script and see the output.

<?php

$a = "a";
$b = "b";
$c = "c";
$d = "d";
$arr = array();
$arr[] =& $a;
$arr[] =& $b;
$arr[] =& $c;
array_splice($arr,1,0,array($d));
$sec_arr = array();
$sec_arr[] =& $d;
array_splice($arr,1,0,$sec_arr);

$arr[0] = "test"; // should be $a
$arr[3] = "test2"; // should be $b
$arr[1] = "this be d?"; // should be $d
$arr[2] = "or this be d?"; // should be $d
var_dump($arr);
var_dump($a);
var_dump($b);
var_dump($d);
?>

The output will be (PHP 4.3.3):

array(5) {
  [0]=>
  &string(4) "test"
  [1]=>
  &string(10) "this be d?"
  [2]=>
  string(13) "or this be d?"
  [3]=>
  &string(5) "test2"
  [4]=>
  &string(1) "c"
}
string(4) "test"
string(5) "test2"
string(10) "this be d?"

So array_splice is reference safe, but you have to be careful about the generation of the replacement array.

have fun, cheers!

down

Paul ¶

18 years ago

In PHP 4.3.10, at least, it seems that elements that are inserted as part of the replacement array are inserted BY REFERENCE (that is, as though with the =& rather than = assignment operation). So if your replacement array contains elements that references to variables that you can also access via other variable name, then this will be true of the elements in the final array too.

In particular, this means that it is safe to use array_splice() on arrays of objects, as you won't be creating copies of the objects (as it is so easy to do in PHP 4).

down

Anonymous ¶

3 years ago

the following:

        $input = [[5=>"richard=red"], [15=>"york=yellow"], [25=>"gave=green"], [30=>"battle=blue"], [35=>"in=indigo"], [40=>"vain=violet"]];
        array_splice($input, 2, 0, [[10=>"of=orange"]]);
        var_dump($input);

gives this:

array (size=7)
  0 => 
    array (size=1)
      5 => string 'richard=red' (length=11)
  1 => 
    array (size=1)
      15 => string 'york=yellow' (length=11)
  2 => 
    array (size=1)
      10 => string 'of=orange' (length=9)
  3 => 
    array (size=1)
      25 => string 'gave=green' (length=10)
  4 => 
    array (size=1)
      30 => string 'battle=blue' (length=11)
  5 => 
    array (size=1)
      35 => string 'in=indigo' (length=9)
  6 => 
    array (size=1)
      40 => string 'vain=violet' (length=11)

down

dead dot screamer at seznam dot cz ¶

15 years ago

I need <?php array_Splice()?> function, that use array keys instead of order (offset and length) because of associated arrays, and this is result:

<?php
/**
 *    first variation
 *
 *    $input is input array
 *    $start is index of slice begin
 *    $end is index of slice end, if this is null, $replacement will be inserted (in the same way as original array_Slice())
 *indexes of $replacement are preserved in both examples
 */
function array_KSplice1(&$input, $start, $end=null, $replacement=null)
{
$keys=array_Keys($input);
$values=array_Values($input);
    if($replacement!==null)
    {
$replacement=(array)$replacement;
$rKeys=array_Keys($replacement);
$rValues=array_Values($replacement);
    }

$start=array_Search($start,$keys,true);
    if($start===false)
        return false;
    if($end!==null)
    {
$end=array_Search($end,$keys,true);
// if $end not found, exit
if($end===false)
            return false;
// if $end is before $start, exit
if($end<$start)
            return false;
// index to length
$end-=$start-1;
    }

// optional arguments
if($replacement!==null)
    {
array_Splice($keys,$start,$end,$rKeys);
array_Splice($values,$start,$end,$rValues);
    }
    else
    {
array_Splice($keys,$start,$end);
array_Splice($values,$start,$end);
    }

$input=array_Combine($keys,$values);

    return $input;
}

/**
 *    second variation
 *
 *    $input is input array
 *    $start is index of slice begin
 *    $length is length of slice, what will be replaced, if is zero, $replacement will be inserted (in the same way as original array_Slice())
 */
function array_KSplice2(&$input, $start, $length=0, $replacement=null)
{
$keys=array_Keys($input);
$values=array_Values($input);
    if($replacement!==null)
    {
$replacement=(array)$replacement;
$rKeys=array_Keys($replacement);
$rValues=array_Values($replacement);
    }

$start=array_Search($start,$keys,true);
    if($start===false)
        return false;

// optional arguments
if($replacement!==null)
    {
array_Splice($keys,$start,$length,$rKeys);
array_Splice($values,$start,$length,$rValues);
    }
    else
    {
array_Splice($keys,$start,$length);
array_Splice($values,$start,$length);
    }

$input=array_Combine($keys,$values);

    return $input;
}

$array=range(1,10);
var_Dump(array_KSplice1($array,3,3,array(100=>101,102,103,104)));

$array=range(1,10);
var_Dump(array_KSplice2($array,3,3,array(100=>101,102,103,104)));

?>

Both examples output:
array(11) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
  [100]=>
  int(101)
  [101]=>
  int(102)
  [102]=>
  int(103)
  [103]=>
  int(104)
  [6]=>
  int(7)
  [7]=>
  int(8)
  [8]=>
  int(9)
  [9]=>
  int(10)
}

down

paule at cs dot tamu dot edu ¶

22 years ago

to kokos@lac.lviv.ua:

Good point about the code not doing what you expected.

The failure to check for the insert case like you pointed out is not a bug, however. I didn't add code to handle that because the key of such an added index is more or less undefined in an unordered associative array. Put another way, if your array is associative and not auto-indexed, you most likely care enough about your keys to want to set them explicitly.

down

Anonymous ¶

22 years ago

Please note that array_splice() 's second argument is an OFFSET and not an INDEX.


Lets say you want to 

$array_of_items = array ('nothing','myitem','hisitem','heritem');

$sid = array_search('myitem',$array_of_items);

echo $sid; /* prints out 1, since index element 1 is "myitem" */


Now, lets say we want to remove that "myitem" from the array:


<?php

$array_of_items = array_splice($array_of_items,(1+$sid),1);

?>



Notice how you have to add a one to the $sid variable?  That is because offset item 1 is "nothing" and since $sid is currently 1 (the index of "myitem"), we add 1 more to it to find out

 its OFFSET.


DO NOT DO THIS:

 $array_of_items = array_splice($array_of_items,$sid,1);

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vitospericolato at gmail dot com ¶

8 years ago

To remove elements from an array, based on array values:

<?php
$i_to_remove=array();

foreach($array_to_prune as $i=>$value){
  if(cond_to_delete($value)) $i_to_remove[]=$i;
}
foreach($i_to_remove as $j=>$i)
array_splice($array_to_prune,$i-$j,1);

?>

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Hayley Watson ¶

6 years ago

For an analogous function that works on strings rather than arrays, see substr_replace.

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antrik ¶

10 years ago

Prompted by dire need, and inspired by some of the existing notes, I came up with this:

/* Like array_splice(), but preserves the key(s) of the replacement array. */
function array_splice_assoc(&$input, $offset, $length = 0, $replacement = array()) {
  $tail = array_splice($input, $offset);
  $extracted = array_splice($tail, 0, $length);
  $input += $replacement + $tail;
  return $extracted;
};

Apart from preserving the keys, it behaves just like the regular array_splice() for all cases I could think of.

So for example the regular array_splice()

$input = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5, 'f' =>6);
print_r(array_splice($input, -4, 3, array('foo1' => 'bar', 'foo2' => 'baz'))); 
print_r($input); 

will give:

Array
(
    [c] => 3
    [d] => 4
    [e] => 5
)
Array
(
    [a] => 1
    [b] => 2
    [0] => bar
    [1] => baz
    [f] => 6
)

But with array_splice_assoc()

$input = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5, 'f' =>6);
print_r(array_splice_assoc($input, -4, 3, array('foo1' => 'bar', 'foo2' => 'baz')));
print_r($input);

we get:

Array
(
    [c] => 3
    [d] => 4
    [e] => 5
)
Array
(
    [a] => 1
    [b] => 2
    [foo1] => bar
    [foo2] => baz
    [f] => 6
)

A typical use case would be replacing an element identified by a particular key, which we could achieve with:

$input = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5, 'f' =>6);
array_splice_assoc($input, array_search('d', array_keys($input)), 1, array('foo' => 'bar'));
print_r($input);

giving us:

Array
(
    [a] => 1
    [b] => 2
    [c] => 3
    [foo] => bar
    [e] => 5
    [f] => 6
)

down

news_yodpeirs at thoftware dot de ¶

13 years ago

Sometimes you may want to insert one array into another and just work on with the resulting array. array_splice() doesn't support this, as the resulting array isn't the returned value but the first argument, which is changed by reference.


Therefore you may use the following function, which inserts array $ins in array $src at position $pos. $rep can be used if $ins shouldn't be just inserted, but should replace some existing elements (the number of elements to be replaced is given in $rep).


<?php

function array_insert($src,$ins,$pos,$rep=0) {

array_splice($src,$pos,$rep,$ins);

  return($src);

}

?>

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bdjumakov at gmail dot com ¶

17 years ago

Someone might find this function usefull. It just takes a given element from the array and moves it before given element into the same array.

<?php
function array_move($which, $where, $array)
{
$tmp  = array_splice($array, $which, 1);
array_splice($array, $where, 0, $tmp);
    return $array;
}
?>

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paule at cs dot tamu dot edu ¶

22 years ago

After reading KoKos' post above, I thought that the code I posted right before his should do what he wanted. However, my original post neglected to note the little "Tip" in the documentation above, about a single element replacement.


If one changes the lines in my code above that says:


<?php

if(is_array($replacement))

                    foreach($replacement as $r_key=>$r_value)

$new_array[$r_key]=$r_value;

?>



to instead say:


<?php

if(is_string($replacement))

$new_array[$key]=$replacement;

                elseif(is_array($replacement))

                    foreach($replacement as $r_key=>$r_value)

$new_array[$r_key]=$r_value;

?>



that will solve the problem.


Sorry for the omission.

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kokos at lac dot lviv dot ua ¶

22 years ago

It may seem obvious from the above posts, but cost me a bit of

braindamage to figure this out...


Contrary to the equivalence noted on this page

$input[$x] = $y   <==>   array_splice ($input, $x, 1, $y)

array_splice() will not always work as expected, 

even provided that you have only INTEGER keys!


The following code:

   $t=array('a','b','c','d','e');

   var_dump($t);


<?php

unset($t[0],$t[1],$t[3]);

$t[0]='f';

var_dump($t);


array_splice($t,0,1,'g');

var_dump($t);

?>



Will produce:

array(5) {

  [0]=>

  string(1) "a"

  [1]=>

  string(1) "b"

  [2]=>

  string(1) "c"

  [3]=>

  string(1) "d"

  [4]=>

  string(1) "e"

}

array(3) {

  [2]=>

  string(1) "c"

  [4]=>

  string(1) "e"

  [0]=>

  string(1) "f"

}

array(3) {

  [0]=>

  string(1) "g"

  [1]=>

  string(1) "e"

  [2]=>

  string(1) "f"

}


Note the position of $t[0] in the second call to var_dump().

And of course, array_splice() left it intact, changing $t[2] instead.

This is because it operates the _offset_, not the _index_.  :)

I think that "equivalence note" should be considered buggy.  ;)))


Best wishes.

KoKos.

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-1

rolandfoxx at yahoo dot com ¶

20 years ago

Be careful, array_splice does not behave like you might expect should you try to pass it an object as the replacement argument.  Consider the following:

<?php
//Very truncated
class Tree {
  var $childNodes

function addChild($offset, $node) {
array_splice($this->childNodes, $offset, 0, $node);
//...rest of function
}

}

class Node {
  var $stuff
...
}

$tree = new Tree();
// ...set 2 nodes using other functions...
echo (count($tree->childNodes)); //Gives 2
$newNode = new Node();
// ...set node attributes here...
$tree->addChild(1, $newNode);
echo(count($tree->childNodes)); //Expect 3?  wrong!
?>

In this case, the array has a number of items added to it equal to the number of attributes in the new Node object and the values thereof  I.e, if your Node object has 2 attributes with values "foo" and "bar", count($tree->childNodes) will now return 4, with the items "foo" and "bar" added to it.  I'm not sure if this qualifies as a bug, or is just a byproduct of how PHP handles objects.

Here's a workaround for this problem:
function array_insertobj(&$array, $offset, $insert) {
  $firstPart = array_slice($array, 0, $offset);
  $secondPart = array_slice($array, $offset);
  $insertPart = array($insert);
  $array = array_merge($firstPart, $insertPart, $secondPart);
}

Note that this function makes no allowances for when $offset equals the first or last index in the array.  That's because array_unshift and array_push work just fine in those cases.  It's only array_splice that can trip you up.  Obviously, this is kinda tailor-made for arrays with numeric keys when you don't really care what said keys are, but i'm sure you could adapt it for associative arrays if you needed it.

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-2

madmax at max-worlds dot net ¶

15 years ago

Note:  If replacement is not an array, it will be typecast to one (i.e. (array) $parameter). This may result in unexpected behavior when using an object replacement .  


Example :


<?php

class A()

{

    private $a;

    private $b;

    public function __construct()

    {

$this->a = "foo";

$this->b = "bar";

    }

}


$array = array();

array_splice($array, 0, 0, new A());

print_r($array);

?>



Outputs :


Array : Array

{

    [0] => foo

    [1] => bar

}


Solution : Enforce the array() on the object.


<?php

array_splice($array, 0, 0, array(new Object());

?>



Source : http://bugs.php.net/bug.php?id=44485

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-2

tsunaquake DOESNTLIKESPAM @ wp DOT pl ¶

21 years ago

It is possible to use a string instead of offset, eg if you want to deletre the entry $myArray['entry'] then you can simply do it like this:


<?php

array_splice($myArray, 'entry', 1);

?>



Note that you can use unset($myArray['entry']) as well but then, it doesn't enable you to remove more than one entry and it doesn't replace anything in the array, if that's what you intend to do.

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-2

Anonymous ¶

9 years ago

<?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;     
}
?>

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-5

strata_ranger at hotmail dot com ¶

15 years ago

Should you want a similar function for splicing strings together, here is a rough equivalent:

<?php
function str_splice($input, $offset, $length=null, $splice='')
{
$input = (string)$input;
$splice = (string)$splice;
$count = strlen($input);

// Offset handling (negative values measure from end of string)
if ($offset<0) $offset = $count + $offset;

// Length handling (positive values measure from $offset; negative, from end of string; omitted = end of string)
if (is_null($length)) $length = $count;
  elseif ($length < 0)  $length = $count-$offset+$length;

// Do the splice
return substr($input, 0, $offset) . $splice . substr($input, $offset+$length);
}

$string = "The fox jumped over the lazy dog.";

// Outputs "The quick brown fox jumped over the lazy dog."
echo str_splice($string, 4, 0, "quick brown ");

?>

Obviously this is not for cases where all you need to do is a simple search-and-replace.

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-4

leingang AT math DOT rutgers DOT edu ¶

22 years ago

array_splice resets the internal pointer of $input. In fact, many array functions do this. Caveat programmor!

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-3

loushou - life dot 42 at gmail dot com ¶

16 years ago

i miss posted the actual function...
here is the real one lol

<?php

function q_sort(&$Info, $Index, $Left, $Right)
{
  echo "memory usage <b>".memory_get_usage()."</b><br/>\n";
$L_hold = $Left;
$R_hold = $Right;
$Pivot = $Left;
$PivotValue = $Info[$Left];
  while ($Left < $Right)
  {
    while (($Info[$Right][$Index] >= $PivotValue[$Index]) && ($Left < $Right))
$Right--;
    if ($Left != $Right)
    {
$Info[$Left] = $Info[$Right];
$Left++;
    }
    while (($Info[$Left][$Index] <= $PivotValue[$Index]) && ($Left < $Right))
$Left++;
    if ($Left != $Right)
    {
$Info[$Right] = $Info[$Left];
$Right--;
    }
  }
$Info[$Left] = $PivotValue;
$Pivot = $Left;
$Left = $L_hold;
$Right = $R_hold;
  if ($Left < $Pivot)
q_sort($Info, $Index, $Left, $Pivot-1);
  if ($Right > $Pivot)
q_sort($Info, $Index, $Pivot+1, $Right);
}

?>

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array_splice

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