For an analogous function that works on strings rather than arrays, see substr_replace.
(PHP 4, PHP 5, PHP 7)
array_splice — 去掉数组中的某一部分并用其它值取代
&$input
, int $offset
[, int $length = count($input)
[, mixed $replacement = array()
]] )
把 input 数组中由
offset 和 length
指定的单元去掉，如果提供了 replacement 参数，则用其中的单元取代。
注意
input 中的数字键名不被保留。
Note: 如果
replacement不是数组，会被 类型转换 成数组 (例如：(array) $replacement)。 当传入的replacement是个对象或者NULL，会导致未知的行为出现。
input输入的数组。
offset
如果 offset 为正，则从 input
数组中该值指定的偏移量开始移除。如果 offset
为负，则从 input 末尾倒数该值指定的偏移量开始移除。
length
如果省略 length，则移除数组中从 offset
到结尾的所有部分。如果指定了 length
并且为正值，则移除这么多单元。如果指定了 length
并且为负值，则移除从 offset 到数组末尾倒数
length 为止中间所有的单元。
如果设置了 length 为零，不会移除单元。
小窍门：当给出了
replacement 时要移除从 offset
到数组末尾所有单元时，用 count($input) 作为 length。
replacement
如果给出了 replacement 数组，则被移除的单元被此数组中的单元替代。
如果
offset 和 length
的组合结果是不会移除任何值，则 replacement
数组中的单元将被插入到 offset
指定的位置。 注意替换数组中的键名不保留。
如果用来替换 replacement 只有一个单元，那么不需要给它加上
array()，除非该单元本身就是一个数组、一个对象或者 NULL。
返回一个包含有被移除单元的数组。
Example #1 array_splice() 例子
<?php
$input = array("red", "green", "blue", "yellow");
array_splice($input, 2);
// $input is now array("red", "green")
$input = array("red", "green", "blue", "yellow");
array_splice($input, 1, -1);
// $input is now array("red", "yellow")
$input = array("red", "green", "blue", "yellow");
array_splice($input, 1, count($input), "orange");
// $input is now array("red", "orange")
$input = array("red", "green", "blue", "yellow");
array_splice($input, -1, 1, array("black", "maroon"));
// $input is now array("red", "green",
// "blue", "black", "maroon")
$input = array("red", "green", "blue", "yellow");
array_splice($input, 3, 0, "purple");
// $input is now array("red", "green",
// "blue", "purple", "yellow");
?>
Example #2 array_splice() 例子
以下表达式以同样方式修改了 $input：
<?php
// 添加两个新元素到 $input
array_push($input, $x, $y);
array_splice($input, count($input), 0, array($x, $y));
// 移除 $input 中的最后一个元素
array_pop($input);
array_splice($input, -1);
// 移除 $input 中第一个元素
array_shift($input);
array_splice($input, 0, 1);
// 在 $input 的开头插入一个元素
array_unshift($input, $x, $y);
array_splice($input, 0, 0, array($x, $y));
// 在 $input 的索引 $x 处替换值
$input[$x] = $y; // 对于键名和偏移量等值的数组
array_splice($input, $x, 1, $y);
?>
For an analogous function that works on strings rather than arrays, see substr_replace.
array_splice with preserve keys
<?php
function array_splice_preserve_keys(&$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"
* }
*/
?>
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-$j,1);
?>
array_splice() does not preserve numeric keys. The function posted by "weikard at gmx dot de" won't do that either because array_merge() does not preserve numeric keys either.
Use following function instead:
<?php
function arrayInsert($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).
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
}
}
<?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 $tmp;
}
?>
Prompted by dire need, and inspired by some of the existing notes, I came up with this:
/* Like array_splice(), but preserves the key(s) of the replacement array. */
function array_splice_assoc(&$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
)
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 $offset === 0 ?>, in which case the array is returned as-is and not, as you might expect, an empty array because everything is stripped off. Obviously it is not really useful anyway to "strip off everything", but I was reminded of that the hard way and this may spare someone some time, hopefully.
When trying to splice an associative array into another, array_splice is missing two key ingredients:
- a string key for identifying the offset
- the ability to preserve keys in the replacement array
This is primarily useful when you want to replace an item in an array with another item, but want to maintain the ordering of the array without rebuilding the array one entry at a time.
<?php
function array_splice_assoc(&$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.
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'
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);
}
?>
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
)
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
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);
// $input is array("red", "green", "blue", "yellow")
?>
Should you want a similar function for splicing strings together, here is a rough equivalent:
<?php
function str_splice($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.
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)
}
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
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, $Right);
}
?>
Do you need to sort a 2D array on just one of its variables while trying to preserve somewhat the original order?
<?php
function sort_2d_array($array, $position, $order = "ASC"){
if (!is_array($array)) return $array;
if (count($array) < 2) return $array;
$new = array($array[0]);
for ($cnt = 1; $cnt <= count($array) - 1; $cnt++){
$stop = 0;
$splice = 0;
for ($newcnt = 0; $newcnt <= count($new) - 1; $newcnt++){
if ($stop == 0){
if ($order == "ASC")
if ($array[$cnt][$position] < $new[$newcnt][$position]){
$splice = $newcnt;
$stop = 1;
} // splice position for ASC
if ($order == "DESC")
if ($array[$cnt][$position] > $new[$newcnt][$position]){
$splice = $newcnt;
$stop = 1;
} // splice position for DESC
} // stop vying for position
} // cycle through new array to find position
if ($stop == 0){
$new[] = $array[$cnt];
} else {
array_splice($new, $splice, 0, array($array[$cnt]));
} // splice into new array while keeping somewhat the original order
} // cycle through original array
return $new;
} // sort_2d_array
?>
Application Example: In-House Search Engine
Here we are trying to find the word apple in the website by sort of the most recent occurances first, but the number of occurances first.
We've already sorted the mysql output by the date desc and have counted the no of occurances and have placed those in an array for the final query.
I've used this function to further sort the occurances but somewhat keep the original mysql sort order.
Key
[0] Record number
[0] Record ID
[1] Source Table
[2] No of Occurances Pinged
---------------------------
[0]
[0] 24530
[1] Blogs
[2] 1
[1]
[0] 24400
[1] Blogs
[2] 1
[2]
[0] 24240
[1] Blogs
[2] 4
[3]
[0] 243422
[1] Classifieds
[2] 1
[4]
[0] 243100
[1] Classifieds
[2] 1
After running...
<?php
sort_2d_array($array, 2, "DESC");
?>
We have...
[0]
[0] 24240
[1] Blogs
[2] 4
[1]
[0] 24530
[1] Blogs
[2] 1
[2]
[0] 24400
[1] Blogs
[2] 1
[3]
[0] 243422
[1] Classifieds
[2] 1
[4]
[0] 243100
[1] Classifieds
[2] 1
Might be useful to someone...
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);
}
?>
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($d);
?>
The output will be (PHP 4.3.3):
array(5) {
[0]=>
&string(4) "test"
[1]=>
&string(10) "this be d?"
[2]=>
string(13) "or this be d?"
[3]=>
&string(5) "test2"
[4]=>
&string(1) "c"
}
string(4) "test"
string(5) "test2"
string(10) "this be d?"
So array_splice is reference safe, but you have to be careful about the generation of the replacement array.
have fun, cheers!
A comment on array_merge mentioned that array_splice is faster than array_merge for inserting values. This may be the case, but if your goal is instead to reindex a numeric array, array_values() is the function of choice. Performing the following functions in a 100,000-iteration loop gave me the following times: ($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
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;
}
?>
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).
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.
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, $a2);
?>
Csaba Gabor from Vienna
To split an associative array based on it's keys, use this function:
<?php
function &array_split(&$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!
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);
?>
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 $offset equals the first or last index in the array. That's because array_unshift and array_push work just fine in those cases. It's only array_splice that can trip you up. Obviously, this is kinda tailor-made for arrays with numeric keys when you don't really care what said keys are, but i'm sure you could adapt it for associative arrays if you needed it.
[ Editor's Note: If you're not concerned with the indexes being contiguously numbered (such as for an associative array) then unset($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, $b);
?>
key-safe:
<?php
function array_kslice ($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 :)
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.
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,$sid,1);
to kokos@lac.lviv.ua:
Good point about the code not doing what you expected.
The failure to check for the insert case like you pointed out is not a bug, however. I didn't add code to handle that because the key of such an added index is more or less undefined in an unordered associative array. Put another way, if your array is associative and not auto-indexed, you most likely care enough about your keys to want to set them explicitly.
After reading KoKos' post above, I thought that the code I posted right before his should do what he wanted. However, my original post neglected to note the little "Tip" in the documentation above, about a single element replacement.
If one changes the lines in my code above that says:
<?php
if(is_array($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.
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.
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.
array_splice resets the internal pointer of $input. In fact, many array functions do this. Caveat programmor!