数组 函数
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array_push

(PHP 4, PHP 5)

array_push — 将一个或多个单元压入数组的末尾（入栈）

说明

int array_push ( array &$array , mixed $var [, mixed $... ] )

array_push() 将 array 当成一个栈，并将传入的变量压入 array 的末尾。array 的长度将根据入栈变量的数目增加。和如下效果相同：

<?php
$array[] = $var;
?>
并对每个 var 重复以上动作。

返回数组新的单元总数。

Example #1 array_push() 例子

<?php
$stack = array("orange", "banana");
array_push($stack, "apple", "raspberry");
print_r($stack);
?>

本例将使 $stack 具有如下单元： 

Array
(
    [0] => orange
    [1] => banana
    [2] => apple
    [3] => raspberry
)

Note: 如果用 array_push() 来给数组增加一个单元，还不如用 $array[] = ，因为这样没有调用函数的额外负担。

Note: 如果第一个参数不是数组，array_push() 将发出一条警告。这和 $var[] 的行为不同，后者会新建一个数组。

参见 array_pop()，array_shift() 和 array_unshift()。

数组 函数
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PHP手册
PHP手册 - N: 将一个或多个单元压入数组的末尾（入栈）

用户评论:

Rodrigo de Aquino (30-Mar-2012 11:24)

If you're going to use array_push() to insert a "$key" => "$value" pair into an array, it can be done using the following:

    $data[$key] = $value;

It is not necessary to use array_push.

Chicna (21-Mar-2012 06:14)

I found a simple way to have an "array_push_array" function, without the references problem when we want to use call_user_func_array(), hope this help :

function array_push_array(array &$array)
{
    $numArgs = func_num_args();
    if(2 > $numArgs)
    {
      trigger_error(sprintf('%s: expects at least 2 parameters, %s given', __FUNCTION__, $numArgs), E_USER_WARNING);
      return false;
    }
   
    $values = func_get_args();
    array_shift($values);
  
    foreach($values as $v)
    {
      if(is_array($v))
      {
        if(count($v) > 0)
        {
          foreach($v as $w)
          {
            $array[] = $w;
          }
        }
      }
      else
      {
        $array[] = $v;
      }
    }
   
    return count($array);
}

Szorstki (27-Dec-2011 10:35)

With multidimensional arrays it's easy too (somebody posted a sample, but it isn't useful for beginners). Here is a piece of code that should explain everything and much more:

<?php
//two classes of objects which will be in multidimensional array
class Org {
    public $name;
    public function __construct($name) {
        $this->name = $name;
    }
}
class Org2 {
    public $name;
    public function __construct($name) {
        $this->name = $name;
    }
}

//main array
$arr = array();

//creating first subarray manually
//the subarray name must be like first class above
$arr['Org'] = array();

//creating second subarray for objects of selected class
//in another way
$x=2222;        //only for creating the sample object
$arr[get_class(new Org2("wtf".$x))] = array();

//pushing some new objects to (sub)arrays in (main)array
for ($i=0; $i<3; $i++) {
    $org1 = new Org("tst".$i);
    $org2 = new Org2("wtf".$i);
    array_push($arr[get_class($org1)], $org1);
    array_push($arr[get_class($org2)], $org2);
}

//printing everything
foreach ($arr as $key=>$value) {
    $counter = 0;
    echo "=====".$key." (key) | value: ".$value."<br/>";
    foreach ($value as $key2=>$value2) {
        if($value2 == null) {
            //echo "counter: ".$counter." | key: ".$key2;
            unset($arr[$key][$key2]);
        } else {
            print_r($value2);
            echo " [".$counter."]  [".$key2."]<br/>";
        }
        $counter++;
    }
}

//the additional, second part
echo "<br/>--------<br/><br/>";
//deleting one of the objects from selected (sub)array
unset($arr['Org'][1]);

//printing everything again (look at the counter values)
foreach ($arr as $key=>$value) {
    $counter = 0;
    echo "=====".$key." (key) | value: ".$value."<br/>";
    foreach ($value as $key2=>$value2) {
        if($value2 == null) {
            //echo "counter: ".$counter." | key: ".$key2;
            unset($arr[$key][$key2]);
        } else {
            print_r($value2);
            echo " [".$counter."]  [".$key2."]<br/>";
        }
        $counter++;
    }
}
?>

What we get in browser/console:
=====Org (key) | value: Array
Org Object ( [name] => tst0 ) [0] [0]
Org Object ( [name] => tst1 ) [1] [1]
Org Object ( [name] => tst2 ) [2] [2]
=====Org2 (key) | value: Array
Org2 Object ( [name] => wtf0 ) [0] [0]
Org2 Object ( [name] => wtf1 ) [1] [1]
Org2 Object ( [name] => wtf2 ) [2] [2]

--------

=====Org (key) | value: Array
Org Object ( [name] => tst0 ) [0] [0]
Org Object ( [name] => tst2 ) [1] [2]
=====Org2 (key) | value: Array
Org2 Object ( [name] => wtf0 ) [0] [0]
Org2 Object ( [name] => wtf1 ) [1] [1]
Org2 Object ( [name] => wtf2 ) [2] [2]

yuri (30-Nov-2011 06:00)

If you want to put an element to a specific position in an array, try this function.

<?php

function array_put_to_position(&$array, $object, $position, $name = null)
{
        $count = 0;
        $return = array();
        foreach ($array as $k => $v)
        {  
                // insert new object
                if ($count == $position)
                {  
                        if (!$name) $name = $count;
                        $return[$name] = $object;
                        $inserted = true;
                }  
                // insert old object
                $return[$k] = $v;
                $count++;
        }  
        if (!$name) $name = $count;
        if (!$inserted) $return[$name];
        $array = $return;
        return $array;
}
?>

Example :

<?php
$a = array(
 'a' => 'A',
 'b' => 'B',
 'c' => 'C',
);
           
print_r($a);
array_put_to_position($a, 'G', 2, 'g');
print_r($a);

/*
Array
(
    [a] => A
    [b] => B
    [c] => C
)
Array
(
    [a] => A
    [b] => B
    [g] => G
    [c] => C
)
*/
?>

aosojnik at gmail dot com (23-Nov-2009 10:56)

If you want to preserve the keys in the array, use the following:

<?php
function array_pshift(&$array) {
    $keys = array_keys($array);
    $key = array_shift($keys);
    $element = $array[$key];
    unset($array[$key]);
    return $element;
}
?>

rarioj at gmail dot com (05-Oct-2009 02:44)

This function "Returns the new number of elements in the array."

To find out the last index, use:

<?php
$count = array_push($array, $value);
$last_index = array_pop(array_keys($array));
?>

Anonymous (20-Sep-2009 10:00)

If you need to push the elements of an array onto the end of another, simply use array_splice():

array_splice($array, count($array), 0, $otherArray);

helpmepro1 at gmail dot com (13-Jan-2009 09:43)

elegant php array combinations algorithm

<?

//by Shimon Dookin

function get_combinations(&$lists,&$result,$stack=array(),$pos=0)
{
 $list=$lists[$pos];
 if(is_array($list))
  foreach($list as $word)
  {
   array_push($stack,$word);
   if(count($lists)==count($stack))
    $result[]=$stack;
   else
    get_combinations($lists,$result,$stack,$pos+1);
   array_pop($stack);
  }
}

$wordlists= array( array("shimon","doodkin") , array("php programmer","sql programmer","mql metatrader programmer") );

get_combinations($wordlists,$combinations);

echo '<xmp>';
print_r($combinations);

?>

wesleys at opperschaap dot net (10-Oct-2008 08:58)

A function which mimics push() from perl, perl lets you push an array to an array: push(@array, @array2, @array3). This function mimics that behaviour.

<?php

function array_push_array(&$arr) {
    $args = func_get_args();
    array_shift($args);

    if (!is_array($arr)) {
        trigger_error(sprintf("%s: Cannot perform push on something that isn't an array!", __FUNCTION__), E_USER_WARNING);
        return false;
    }

    foreach($args as $v) {
        if (is_array($v)) {
            if (count($v) > 0) {
                array_unshift($v, &$arr);
                call_user_func_array('array_push',  $v);
            }
        } else {
            $arr[] = $v;
        }
    }
    return count($arr);
}

$arr = array(0);
$arr2  = array(6,7,8);
printf("%s\n", array_push_array($arr, array(),array(1,2,3,4,5), $arr2));
print_r($arr);

# error..
$arr = "test";
printf("%s\n", array_push_array($arr, array(),array(1,2,3,4,5), $arr2));

?>

willdemaine at gmail dot com (07-Aug-2008 03:00)

If you're adding multiple values to an array in a loop, it's faster to use array_push than repeated [] = statements that I see all the time:

<?php
class timer
{
        private $start;
        private $end;

        public function timer()
        {
                $this->start = microtime(true);
        }

        public function Finish()
        {
                $this->end = microtime(true);
        }

        private function GetStart()
        {
                if (isset($this->start))
                        return $this->start;
                else
                        return false;
        }

        private function GetEnd()
        {
                if (isset($this->end))
                        return $this->end;
                else
                        return false;
        }

        public function GetDiff()
        {
                return $this->GetEnd() - $this->GetStart();
        }

        public function Reset()
        {
                $this->start = microtime(true);
        }

}

echo "Adding 100k elements to array with []\n\n";
$ta = array();
$test = new Timer();
for ($i = 0; $i < 100000; $i++)
{
        $ta[] = $i;
}
$test->Finish();
echo $test->GetDiff();

echo "\n\nAdding 100k elements to array with array_push\n\n";
$test->Reset();
for ($i = 0; $i < 100000; $i++)
{
        array_push($ta,$i);
}
$test->Finish();
echo $test->GetDiff();

echo "\n\nAdding 100k elements to array with [] 10 per iteration\n\n";
$test->Reset();
for ($i = 0; $i < 10000; $i++)
{
        $ta[] = $i;
        $ta[] = $i;
        $ta[] = $i;
        $ta[] = $i;
        $ta[] = $i;
        $ta[] = $i;
        $ta[] = $i;
        $ta[] = $i;
        $ta[] = $i;
        $ta[] = $i;
}
$test->Finish();
echo $test->GetDiff();

echo "\n\nAdding 100k elements to array with array_push 10 per iteration\n\n";
$test->Reset();
for ($i = 0; $i < 10000; $i++)
{
        array_push($ta,$i,$i,$i,$i,$i,$i,$i,$i,$i,$i);
}
$test->Finish();
echo $test->GetDiff();
?>

Output

$ php5 arraypush.php
X-Powered-By: PHP/5.2.5
Content-type: text/html

Adding 100k elements to array with []

0.044686794281006

Adding 100k elements to array with array_push

0.072616100311279

Adding 100k elements to array with [] 10 per iteration

0.034690141677856

Adding 100k elements to array with array_push 10 per iteration

0.023932933807373

Ariz Jacinto (28-Jun-2008 12:41)

if you're going to use array_push() to insert a "$key" => "$value" pair into an array, it can be done using the following example:

    array_push($data[$key], $value);
    ...
    array_push($data[$key], $value);

bxi at apparoat dot nl (23-May-2008 12:29)

I've done a small comparison between array_push() and the $array[] method and the $array[] seems to be a lot faster.

<?php
$array = array();
for ($x = 1; $x <= 100000; $x++)
{
    $array[] = $x;
}
?>
takes 0.0622200965881 seconds

and

<?php
$array = array();
for ($x = 1; $x <= 100000; $x++)
{
    array_push($array, $x);
}
?>
takes 1.63195490837 seconds

so if your not making use of the return value of array_push() its better to use the $array[] way.

Hope this helps someone.

alexander dot williamson at gmail dot com (27-Mar-2008 12:06)

This will work to solve the associative array issues:

$aValues[$key] = $value;

Where $key is a unique identifier and $value is the value to be stored. Since the $key works off a string or number, if you already have a $key with the same value as an existing $key, the element will be overwritten.

e.g.

$aValues["one"] = "value of one";
$aValues["two"] = "different value of two!";

gives:
array([one] => "value of one", [two] => "value of two");

but will be overwritten when using the same key (one):

$aValues["one"] = "value of one";
$aValues["one"] = "different value of two!";

will give:

array([one] => "different value of two!");

3686

darkimmortal at dkimmortal dot com (18-Feb-2008 07:31)

I wrote this function for use with 'latest scores' on a quiz site, but it has many potential uses.

<?php
/**
* @desc array_push and removes elements from the beginning of the array until it is within limit
* @param    array   Array to push on to
* @param    mixed   Passed to array push as 2nd parameter
* @param    int     Limit (default = 10)
*
* @return   array   New array
*/
function array_push_limit($array,$add,$limit=10){
    array_push($array, $add);   
    do {       
        array_shift($array);
        $size=count($array);       
    } while($size > $limit);
       
    return $array;
}
?>
----------
EXAMPLE:
----------
<?php
    $array=array(1, -5, 23, -66, 33, 54, 3);   
    print_r(array_push_limit($array, "HELLO", 4));
?>
----------
OUTPUT:
----------
Array
(
    [0] => 33
    [1] => 54
    [2] => 3
    [3] => HELLO
)

rob AT rate for the cure dot com (15-Aug-2007 05:09)

I had a problem with .htaccess and some tricky encrypted paths (for protecting true dir names of images and files) and created this quick function to auto correct paths for the document root using regex and array_diff
<?
function fixPath($path){
        $temp = trim($path);
        $temp = eregi_replace("(\./|\.\./)","/",$temp);
        $temp = eregi_replace("([^/]+(\.htm|\.php))","",$temp);
        if(!eregi($_SERVER['DOCUMENT_ROOT'],$temp,$regs)){
            $partsA = explode("/",substr($temp,0,-1));
            $partsB = explode("/",$_SERVER['DOCUMENT_ROOT']);
            //if the path does not match the dir structure diff the array and reconstruct on the TRUE doc root
            $tHolder = array_diff($partsA,$partsB);
                foreach($tHolder as $k=>$v){
                    array_push($partsB,$v);
                }
                       
            $temp =  implode("/",$partsB)."/";
        }
        return $temp;
    }
$correctPath = fixPath('.som/phpEncrypted/Path/class/class.QMI.php');
?>

The function strips out filename, checks to see if the path resolves to the doc root, and if it does not it takes the difference in the paths and returns a path that translates to the true path. This is useful for encoding paths where you want to obfuscate the true server path (such as creating external api functions)

zbde00 at hotmail dot com (20-Jul-2007 01:59)

A very good function to remove a element from array
function array_del($str,&$array)
{
    if (in_array($str,$array)==true)
    {
   
        foreach ($array as $key=>$value)
        {
            if ($value==$str) unset($array[$key]);
        }
    }
}

antido at gmail dot com (03-Aug-2006 09:04)

Simple data object implementation:

<?php

/**
 * Data object
 *
 * @version 0.6
 * @author Tom Reitsma <antido@gmail.com>
 */
Class DataObject
{
    /**
     * @var int $ptr
     */
    private $ptr = 0;
   
    /**
     * @var array $data
     */
    private $data = array();
   
    /**
     * Class constructor
     */
    public function __construct($anArray=false)
    {
        if($anArray != false)
        {
            if(is_array($anArray))
            {
                $this->data[] = $anArray;
            }
        }
    }
   
    /**
     * Fetches the data under the pointer
     *
     * @return String if there is still data left under the pointer, false if the end has been reached
     */
    public function fetch()
    {
        if(isset($this->data[$this->ptr]))
        {
            return $this->data[$this->ptr++];
        }
       
        return false;
    }
   
    /**
     * Moves to the next row in the data object
     *
     * @return boolean
     */
    public function moveNext()
    {
        $newPtr = $this->ptr + 1;
       
        if(isset($this->data[$newPtr]))
        {
            $this->ptr = $newPtr;
            return true;
        }
       
        return false;
    }
   
    /**
     * Moves to the previous row in the data object
     *
     * @return boolean
     */
    public function movePrevious()
    {
        $newPtr = $this->ptr - 1;
       
        if(isset($this->data[$newPtr]))
        {
            return $this->data[$newPtr];
        }
       
        return false;
    }
   
    /**
     * Pushes an element onto the array
     *
     * @param String or an array $input
     * @return number of elements
     */
    public function push($input)
    {
        if($this->getNumRows() > 0)
        {
            return array_push($this->data, $input);
        }
        else
        {
            return $this->data[] = $input;
        }
    }
   
    /**
     * Counts the number of rows
     */
    public function getNumRows()
    {
        return count($this->data);
    }
}

?>

Marc Bernet (15-May-2006 05:18)

A small and basic implementation of a stack without using an array.

class node
{
        var $elem;
        var    $next;
}
class stack
{
    var $next;
    function pop()
    {
        $aux=$this->next->elem;
        $this->next=$this->next->next;
        return $aux;
    }
    function push($obj)
    {
        $nod=new node;
        $nod->elem=$obj;
        $nod->next=$this->next;
        $this->next=$nod;
    }
    function stack()
    {
        $this->next=NULL;
    }    
}

richard dot udo at gmail dot com (09-Feb-2006 11:05)

Just a typo i think but the code below will actually produce

Array
(
    [0] => a
    [1] => b
    [2] => c
    [3] => Array
        (
            [0] => d
            [1] => e
            [2] => f
        )
)

egingell at sisna dot com (28-Jan-2006 02:06)

If you push an array onto the stack, PHP will add the whole array to the next element instead of adding the keys and values to the array. If this is not what you want, you're better off using array_merge() or traverse the array you're pushing on and add each element with $stack[$key] = $value.

<?php

$stack = array('a', 'b', 'c');
array_push($stack, array('d', 'e', 'f'));
print_r($stack);

?>
The above will output this:
Array (
  [0] => a
  [1] => b
  [2] => c
  [3] => Array (
     [0] => a
     [1] => b
     [2] => c
  )
)

steve at webthoughts d\ot ca (13-Nov-2005 12:02)

Further Modification on the array_push_associative function
1.  removes seemingly useless array_unshift function that generates php warning
2.  adds support for non-array arguments

<?
// Append associative array elements
function array_push_associative(&$arr) {
   $args = func_get_args();
   foreach ($args as $arg) {
       if (is_array($arg)) {
           foreach ($arg as $key => $value) {
               $arr[$key] = $value;
               $ret++;
           }
       }else{
           $arr[$arg] = "";
       }
   }
   return $ret;
}

$items = array("here" => "now");
$moreitems = array("this" => "that");

$theArray = array("where" => "do we go", "here" => "we are today");
echo array_push_associative($theArray, $items, $moreitems, "five") . ' is the size of $theArray.<br />';
   
echo "<pre>";
print_r($theArray);
echo "</pre>";

?>

Yields:

4 is the size of $theArray.
Array
(
    [where] => do we go
    [here] => now
    [this] => that
    [five] =>
)

ludvig dot ericson at gmail dot com (31-Oct-2005 01:32)

Previous comment was not fully imitating the array_push behaviour,
1) does not return number of items pushed
2) can only handle one array to push

> Revised associative_push function with absolute reference of arg1 array; left unchanged if arg2 is empty.

<?php
// Append associative array elements
function array_push_associative(&$arr) {
    $args = func_get_args();
    array_unshift($args); // remove &$arr argument
    foreach ($args as $arg) {
        if (is_array($arg)) {
            foreach ($arg as $key => $value) {
                $arr[$key] = $value;
                $ret++;
            }
        }
    }
   
    return $ret;
}

$theArray = array();
echo array_push_associative($theArray, $items, $moreitems) . ' items added to $theArray.';
?>

john (19-Oct-2005 09:33)

A variation of kamprettos' associative array push:

// append associative array elements
function associative_push($arr, $tmp) {
  if (is_array($tmp)) {
    foreach ($tmp as $key => $value) {
      $arr[$key] = $value;
    }
    return $arr;
  }
  return false;
}

$theArray = array();
$theArray = associative_push($theArray, $items);

kamprettos at yahoo dot com Teguh Iskanto (19-Sep-2005 01:33)

Looking for a way to push data into an associative array and frustrated to know that array_push() can't do the job ?

here's my Scenario :
-------------------
I need to relate system command output into an associative array like these :

[sge@digital_db work]$ /usr/local/apache/htdocs/work/qhost.sh -h t1 -F | awk '{if(NR>4) print $1}' | sed  's/hl://g'
arch=lx24-amd64
num_proc=2.000000
mem_total=3.808G
swap_total=3.907G
virtual_total=7.715G
load_avg=0.000000
load_short=0.000000
load_medium=0.000000
load_long=0.000000
mem_free=3.510G
swap_free=3.907G
virtual_free=7.417G
mem_used=305.242M
swap_used=0.000
virtual_used=305.242M
cpu=0.000000
np_load_avg=0.000000
np_load_short=0.000000
np_load_medium=0.000000
np_load_long=0.000000

how I did it :
<? php

# get into the system command output
$assoc_cmd =`$work_dir/qhost.sh -h $host_resource -F | awk '{if(NR>4) print $1}'| sed  's/hl://g' ` ;

# split the "\n" character
$assoc_row = explode("\n", chop($assoc_cmd));

# get the index row
$idx_row  = count($assoc_row) - 1 ;

# initialize the associative array
$host_res_array = array();

for ($i = 0 ; $i<= $idx_row ; $i++)
        {      
                # get params & values
                list($host_param,$host_val) = explode("=",$assoc_row[$i]);

                # populate / push data to assoc array
                $host_res_array[$host_param]= $host_val ;
        }   

echo "<pre> Architecture : </pre>\n" ;
echo $host_res_array['arch'] ;
echo "<pre> Mem Total    : </pre>\n" ;
echo $host_res_array['mem_tot'];

?>

Hope this helps ! :)

bk at quicknet dot nl (04-Sep-2005 09:51)

Add elements to an array before or after a specific index or key:

<?php

/**
 * @return array
 * @param array $src
 * @param array $in
 * @param int|string $pos
*/
function array_push_before($src,$in,$pos){
    if(is_int($pos)) $R=array_merge(array_slice($src,0,$pos), $in, array_slice($src,$pos));
    else{
        foreach($src as $k=>$v){
            if($k==$pos)$R=array_merge($R,$in);
            $R[$k]=$v;
        }
    }return $R;
}

/**
 * @return array
 * @param array $src
 * @param array $in
 * @param int|string $pos
*/
function array_push_after($src,$in,$pos){
    if(is_int($pos)) $R=array_merge(array_slice($src,0,$pos+1), $in, array_slice($src,$pos+1));
    else{
        foreach($src as $k=>$v){
            $R[$k]=$v;
            if($k==$pos)$R=array_merge($R,$in);
        }
    }return $R;
}

// Examples:

$src=array("A","B","C");
$in=array("X","Y");

var_dump(array_push_before($src,$in,1));
/* array_push_before, no-key array
array(5) {
  [0]=>
  string(1) "A"
  [1]=>
  string(1) "X"
  [2]=>
  string(1) "Y"
  [3]=>
  string(1) "B"
  [4]=>
  string(1) "C"
}*/

var_dump(array_push_after($src,$in,1));
/* array_push_after, no-key array
array(5) {
  [0]=>
  string(1) "A"
  [1]=>
  string(1) "B"
  [2]=>
  string(1) "X"
  [3]=>
  string(1) "Y"
  [4]=>
  string(1) "C"
}*/

$src=array('a'=>"A",'b'=>"B",'c'=>"C");
$in=array('x'=>"X",'y'=>"Y");

var_dump(array_push_before($src,$in,1));
/* array_push_before, key array, before index insert
array(5) {
  ["a"]=>
  string(1) "A"
  ["x"]=>
  string(1) "X"
  ["y"]=>
  string(1) "Y"
  ["b"]=>
  string(1) "B"
  ["c"]=>
  string(1) "C"
}*/

var_dump(array_push_before($src,$in,'b'));
/* array_push_before, key array, before key insert
array(5) {
  ["a"]=>
  string(1) "A"
  ["x"]=>
  string(1) "X"
  ["y"]=>
  string(1) "Y"
  ["b"]=>
  string(1) "B"
  ["c"]=>
  string(1) "C"
}*/

var_dump(array_push_after($src,$in,1));
/* array_push_after, key array, after index insert
array(5) {
  ["a"]=>
  string(1) "A"
  ["b"]=>
  string(1) "B"
  ["x"]=>
  string(1) "X"
  ["y"]=>
  string(1) "Y"
  ["c"]=>
  string(1) "C"
}*/

var_dump(array_push_after($src,$in,'b'));
/* array_push_after, key array, after key insert
array(5) {
  ["a"]=>
  string(1) "A"
  ["b"]=>
  string(1) "B"
  ["x"]=>
  string(1) "X"
  ["y"]=>
  string(1) "Y"
  ["c"]=>
  string(1) "C"
}*/

?>

ciprian dot amariei at gmail com (30-Aug-2005 10:47)

regarding the speed of oneill's solution to insert a value into a non-associative array,  I've done some tests and I found that it behaves well if you have a small array and more insertions, but for a huge array and a little insersions I sugest  using this function:

function array_insert( &$array, $index, $value ) {
   $cnt = count($array);
 
   for( $i = $cnt-1; $i >= $index; --$i ) {
       $array[ $i + 1 ] = $array[ $i ];
   }
   $array[$index] = $value;
}

or if you are a speed adicted programmer (same situation: big array, few insertions) use this:

array_splice ( $array, $offset, 0, $item );

item may also be an array of values ;).

Phil Davies (18-Jul-2005 11:51)

As someone pointed out the array_push() function returns the count of the array not the key of the new element. As it was the latter function i required i wrote this very simple replacement.

function array_push2(&$array,$object,$key=null){
    $keys = array_keys($array);
    rsort($keys);
    $newkey = ($key==null)?$keys[0]+1:$key;
    $array[$newkey] = $object;
    return $newkey;
}

oneill at c dot dk (03-Jun-2005 09:50)

To insert a value into a non-associative array, I find this simple function does the trick:

function insert_in_array_pos($array, $pos, $value)
{
  $result = array_merge(array_slice($array, 0 , $pos), array($value), array_slice($array,  $pos));
  return $result;
}

Seems an awful lot simpler than the iterative solutions given above...

aaron dot hawley at uvm dot edu (27-May-2005 07:36)

Skylifter notes on 20-Jan-2004 that the [] empty bracket notation does not return the array count as array_push does.  There's another difference between array_push and the recommended empty bracket notation.

Empy bracket doesn't check if a variable is an array first as array_push does.  If array_push finds that a variable isn't an array it prints a Warning message if E_ALL error reporting is on.

So array_push is safer than [], until further this is changed by the PHP developers.

josh at digitalfruition dot com (14-Feb-2005 06:17)

Note that array_push() will, as described, return the COUNT of the array after adding a new item, not necessarily the INDEX of that new item:

<?php
$array = array(3 => 'three', 5 => 'five');

echo "\$array = ";
print_r($array);
echo "\n\n";

$to_push = array(1,2,4,);
foreach($to_push as $var)
{
    echo "calling array_push(\$array,$var); retval is ";
    echo array_push($array,$var);
    echo "\n";
}

echo "\$array = ";
print_r($array);
?>

The output of above is:

$array = Array
(
    [3] => three
    [5] => five
)

calling array_push($array,1); retval is 4
calling array_push($array,2); retval is 5
calling array_push($array,4); retval is 6
$array = Array
(
    [3] => three
    [5] => five
    [7] => seven
    [8] => 1
    [9] => 2
    [10] => 4
)

Notice how when array_push($array,1) was called, the new element has a key of 8 but array_push() returns 4.

andrew at cgipro dot com (02-Feb-2005 11:18)

Need a real one-liner for adding an element onto a new array name?

$emp_list_bic = $emp_list + array(c=>"ANY CLIENT");

CONTEXT...
drewdeal: this turns out to be better and easier than array_push()
patelbhadresh: great!... so u discover new idea...
drewdeal: because you can't do:   $emp_list_bic = array_push($emp_list, c=>"ANY CLIENT");
drewdeal: array_push returns a count and affects current array.. and does not support set keys!
drewdeal: yeah. My one-liner makes a new array as a derivative of the prior array

aron (24-Feb-2004 10:48)

The problem with array_push is that it is pass by value.  If you are dealing with objects whose inner state may change at any time, you need a push and pop who return the actual objects, rather than copies of them. 
After some difficulty and board assistance, I have these methods.  I've tested them, and they seem to work fine.

<?php
function push(&$array, &$object){   
    $array[] =& $object;   
}
function & pop(&$array){
    return array_pop($array);
}

// [Test Code]
class TestObject{
    var $value = 0;
    function getValue(){
        return $this->value;
    }
    function setValue($mixed){
        $this->value = $mixed;
    }
}
$myarr = array();
$tmp =& new TestObject();
$tmp2 =& new TestObject();
$tmp->setValue(2);
$tmp2->setValue(3);

push($myarr, $tmp);
push($myarr, $tmp2);
$tmp->setValue(4);
$tmp2->setValue(6);
$val = pop($myarr);
print "popped value: ".$val->getValue()."<br />";

print "values in internal array: <br />";
foreach ($myarr as $key=>$value){
    print "key: $key, object: $value, value: ";
    print  $value->getValue()."<br />";
}
// [/TestCode]
?>

skiflyer (21-Jan-2004 12:05)

However, don't forget that array_push() does more than [], it also performs a count and returns the value.

Modifying your code ever so slightly (see below), this puts array_push in the lead (not suprisingly).  So my conclusion would be that if I care about the number of elements in the array, then I'd use array_push(), if I don't (which is usually the case), then I'd use the [] method.

Results...
[] method: 0.34943199
push method: 0.31505919
difference: -0.03437280

Modified section of code...
$s_test_begin = FullMicroTime();
for($i = 0; $i <= 50000; $i++) { $num_tot = array_push($test2, $i); }
$s_test_end = FullMicroTime();

$f_test_begin = FullMicroTime();
for($i = 0; $i <= 50000; $i++) { $test[] = $i; $num_tot = count($test); }
$f_test_end = FullMicroTime();

daevid at daevid dot com (17-Feb-2003 04:38)

Sadly, array_push() does not create an array if the array doesn't exist.  So if you're pushing the first element onto an array, you need to check and create it manually...

<?php
if ( !is_array($myArray) ) $myArray= array();
array_push($myArray, $myElement);
?>

bart at framers dot nl (27-Sep-2001 12:16)

Array_push also works fine with multidimensional arrays. Just make sure the element is defined as an array first.

<?php
$array["element"][$element]["element"] = array();
array_push ($array["element"][$element]["element"], "banana");
?>