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.
(PHP 4, PHP 5, PHP 7)
array_push — Push one or more elements onto the end of array
array_push() treats array as a
stack, and pushes the passed variables onto the end of
array. The length of array
increases by the number of variables pushed. Has the same effect as:
<?php
$array[] = $var;
?>
Note: If you use array_push() to add one element to the array it's better to use $array[] = because in that way there is no overhead of calling a function.
Note: array_push() will raise a warning if the first argument is not an array. This differs from the $var[] behaviour where a new array is created.
arrayThe input array.
value1
The first value to push onto the end of the array.
Returns the new number of elements in the array.
Example #1 array_push() example
<?php
$stack = array("orange", "banana");
array_push($stack, "apple", "raspberry");
print_r($stack);
?>
The above example will output:
Array
(
[0] => orange
[1] => banana
[2] => apple
[3] => raspberry
)
If you're going to use array_push() to insert a "$key" => "$value" pair into an array, it can be done using the following:
$data[$key] = $value;
It is not necessary to use array_push.
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.
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
)
)
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
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"
}*/
?>
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
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);
?>
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;
}
?>
Be warned using $array "+=" array(1,2,3) or union operations (http://php.net/manual/en/language.operators.array.php)
I think it worked in the past or i havent test it good enough. :-/
(once it worked, once [] was faster than array_push, the past :-D ):
php -r '$a = array(1,2); $a += array(3,4); print_r($a);'
Array (
[0] => 1
[1] => 2
)
php -r '$a = array(1,2); $b = array(3,4);$c = $a + $b; print_r($c);'
Array (
[0] => 1
[1] => 2
)
php -r '$a = array(1,2); $b = array(2=>3,3=>4);$c = $a + $b; print_r($c);'
Array (
[0] => 1
[1] => 2
[2] => 3
[3] => 4
)
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));
?>
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";
$aValues["one"] = "different value of two!";
will give:
array([one] => "different value of two!");
3686
To insert a value into a non-associative array, I find this simple function does the trick:
function insert_in_array_pos($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...
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()
{
$this->next=NULL;
}
}
I found a simple way to have an "array_push_array" function, without the references problem when we want to use call_user_func_array(), hope this help :
function array_push_array(array &$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);
}
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
)
*/
?>
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
)
)
Unfortunately array_push returns the new number of items in the array
It does not give you the key of the item you just added, in numeric arrays you could do -1, you do however need to be sure that no associative key exists as that would break the assumption
It would have been better if array_push would have returned the key of the item just added like the below function
(perhaps a native variant would be a good idea...)
<?php
if(!function_exists('array_add')){
function array_add(array &$array,$value /*[, $...]*/){
$values = func_get_args(); //get all values
$values[0]= &$array; //REFERENCE!
$org=key($array); //where are we?
call_user_func_array('array_push',$values);
end($array); // move to the last item
$key = key($array); //get the key of the last item
if($org===null){
//was at eof, added something, move to it
return $key;
}elseif($org<(count($array)/2)){ //somewhere in the middle +/- is fine
reset($array);
while (key($array) !== $org) next($List);
}else{
while (key($array) !== $org) prev($List);
}
return $key;
}
}
echo "<pre>\n";
$pr = array('foo'=>'bar','bar'=>'foo');
echo "Taken array;";
print_r($pr);
echo "\npush 1 returns ".array_push($pr,1)."\n";
echo "------------------------------------\n";
$pr = array('foo'=>'bar','bar'=>'foo');
echo "\npush 2 returns ".array_push($pr,1,2)."\n";
echo "------------------------------------\n";
$pr = array('foo'=>'bar','bar'=>'foo');
echo "\n add 1 returns ".array_add($pr,2)."\n\n";
echo "------------------------------------\n";
$pr = array('foo'=>'bar','bar'=>'foo');
echo "\n add 2 returns ".array_add($pr,1,2)."\n\n";
echo "<pre/>\n\n";
?>
Outputs:
Taken array;Array
(
[foo] => bar
[bar] => foo
)
push 1 returns 3
------------------------------------
push 2 returns 4
------------------------------------
add 1 returns 0
------------------------------------
add 2 returns 1
Rodrigo de Aquino asserted that instead of using array_push to append to an associative array you can instead just do...
$data[$key] = $value;
...but this is actually not true. Unlike array_push and even...
$data[] = $value;
...Rodrigo's suggestion is NOT guaranteed to append the new element to the END of the array. For instance...
$data['one'] = 1;
$data['two'] = 2;
$data['three'] = 3;
$data['four'] = 4;
...might very well result in an array that looks like this...
[ "four" => 4, "one" => 1, "three" => 3, "two" => 2 ]
I can only assume that PHP sorts the array as elements are added to make it easier for it to find a specified element by its key later. In many cases it won't matter if the array is not stored internally in the same order you added the elements, but if, for instance, you execute a foreach on the array later, the elements may not be processed in the order you need them to be.
If you want to add elements to the END of an associative array you should use the unary array union operator (+=) instead...
$data['one'] = 1;
$data += [ "two" => 2 ];
$data += [ "three" => 3 ];
$data += [ "four" => 4 ];
You can also, of course, append more than one element at once...
$data['one'] = 1;
$data += [ "two" => 2, "three" => 3 ];
$data += [ "four" => 4 ];
Note that like array_push (but unlike $array[] =) the array must exist before the unary union, which means that if you are building an array in a loop you need to declare an empty array first...
$data = [];
for ( $i = 1; $i < 5; $i++ ) {
$data += [ "element$i" => $i ];
}
...which will result in an array that looks like this...
[ "element1" => 1, "element2" => 2, "element3" => 3, "element4" => 4 ]
I did a performance check, and I saw, if you push more than one value it can be faster the array push, that the normal $array[] version.
Case 1: $array[] = something;
Case 2: array_push($array, $value);
Case 3: array_push($array, $value1, $value2, $value3 [...]); $values are definied
Case 4: array_push($array, $value1, $value2, $value3 [...]); $values are definied, when $array is not empty
Case 5: Case1 + Case 3
Case 6: Result array contains some value (Case 4)
Case 7: Result array contains same value as the push array (Case 4)
-----------------------------------------------------------------------------------------------------------
~~~~~~~~~~~~ Case 1 ~~~~~~~~~~~~
Times: 0.0310 0.0300 0.0290 0.0340 0.0400 0.0440 0.0480 0.0550 0.0570 0.0570
Min: 0.0290
Max: 0.0570
Avg: 0.0425
~~~~~~~~~~~~ Case 2 ~~~~~~~~~~~~
Times: 0.3890 0.3850 0.3770 0.4110 0.4020 0.3980 0.4020 0.4060 0.4130 0.4200
Min: 0.3770
Max: 0.4200
Avg: 0.4003
~~~~~~~~~~~~ Case 3 ~~~~~~~~~~~~
Times: 0.0200 0.0220 0.0240 0.0340 0.0360 0.0410 0.0460 0.0500 0.0520 0.0520
Min: 0.0200
Max: 0.0520
Avg: 0.0377
~~~~~~~~~~~~ Case 4 ~~~~~~~~~~~~
Times: 0.0200 0.0250 0.0230 0.0260 0.0330 0.0390 0.0460 0.0510 0.0520 0.0520
Min: 0.0200
Max: 0.0520
Avg: 0.0367
~~~~~~~~~~~~ Case 5 ~~~~~~~~~~~~
Times: 0.0260 0.0250 0.0370 0.0360 0.0390 0.0440 0.0510 0.0520 0.0530 0.0560
Min: 0.0250
Max: 0.0560
Avg: 0.0419
~~~~~~~~~~~~ Case 6 ~~~~~~~~~~~~
Times: 0.0340 0.0280 0.0370 0.0410 0.0450 0.0480 0.0560 0.0580 0.0580 0.0570
Min: 0.0280
Max: 0.0580
Avg: 0.0462
~~~~~~~~~~~~ Case 7 ~~~~~~~~~~~~
Times: 0.0290 0.0270 0.0350 0.0410 0.0430 0.0470 0.0540 0.0540 0.0550 0.0550
Min: 0.0270
Max: 0.0550
Avg: 0.044
Tester code:
// Case 1
$startTime = microtime(true);
$array = array();
for ($x = 1; $x <= 100000; $x++)
{
$array[] = $x;
}
$endTime = microtime(true);
// Case 2
$startTime = microtime(true);
$array = array();
for ($x = 1; $x <= 100000; $x++)
{
array_push($array, $x);
}
$endTime = microtime(true);
// Case 3
$result = array();
$array2 = array(&$result)+$array;
$startTime = microtime(true);
call_user_func_array("array_push", $array2);
$endTime = microtime(true);
// Case 4
$result = array();
for ($x = 1; $x <= 100000; $x++)
{
$result[] = $x;
}
$array2 = array(&$result)+$array;
$startTime = microtime(true);
call_user_func_array("array_push", $array2);
$endTime = microtime(true);
// Case 5
$result = array();
$startTime = microtime(true);
$array = array(&$result);
for ($x = 1; $x <= 100000; $x++)
{
$array[] = $x;
}
$endTime = microtime(true);
// Case 6
$result = array(1,2,3,4,5,6);
$startTime = microtime(true);
$array = array(&$result);
for ($x = 1; $x <= 100000; $x++)
{
$array[] = $x;
}
$endTime = microtime(true);
// Case 7
$result = array();
for ($x = 1; $x <= 100000; $x++)
{
$result[] = $x;
}
$startTime = microtime(true);
$array = array(&$result);
for ($x = 1; $x <= 100000; $x++)
{
$array[] = $x;
}
$endTime = microtime(true);
<?php
//Push same var into array multiple times
if(!function_exists('m_push')){
function m_push($array, $var, $count){
for ($i = 1; $i <= $count; $i++)
{
$array[] = $var;
}
return $array;
}
}
?>
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));
?>
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
)
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]);
}
}
}
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 $theArray.
Array
(
[where] => do we go
[here] => now
[this] => that
[five] =>
)
Looking for a way to push data into an associative array and frustrated to know that array_push() can't do the job ?
here's my Scenario :
-------------------
I need to relate system command output into an associative array like these :
[sge@digital_db work]$ /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 $host_res_array['mem_tot'];
?>
Hope this helps ! :)
regarding the speed of oneill's solution to insert a value into a non-associative array, I've done some tests and I found that it behaves well if you have a small array and more insertions, but for a huge array and a little insersions I sugest using this function:
function array_insert( &$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, $item );
item may also be an array of values ;).
As someone pointed out the array_push() function returns the count of the array not the key of the new element. As it was the latter function i required i wrote this very simple replacement.
function array_push2(&$array,$object,$key=null){
$keys = array_keys($array);
rsort($keys);
$newkey = ($key==null)?$keys[0]+1:$key;
$array[$newkey] = $object;
return $newkey;
}
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.
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();
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");
?>
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 $theArray.';
?>
The problem with array_push is that it is pass by value. If you are dealing with objects whose inner state may change at any time, you need a push and pop who return the actual objects, rather than copies of them.
After some difficulty and board assistance, I have these methods. I've tested them, and they seem to work fine.
<?php
function push(&$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 $value->getValue()."<br />";
}
// [/TestCode]
?>
If you need to push the elements of an array onto the end of another, simply use array_splice():
array_splice($array, count($array), 0, $otherArray);
A variation of kamprettos' associative array push:
// append associative array elements
function associative_push($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);
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]
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.
I noticed that under certain circumstances it can be faster to use
<?php
call_user_func_array("array_push", array('x' => &$array1) + array_values($array2));
?>
than
<?php
foreach ($array2 as $key => $value) {
$array1[] = $value;
}
?>
Sadly, array_push() does not create an array if the array doesn't exist. So if you're pushing the first element onto an array, you need to check and create it manually...
<?php
if ( !is_array($myArray) ) $myArray= array();
array_push($myArray, $myElement);
?>
i wanted to do some string manipulation on a specific field from an sql result set and then append the row to the end of an array like this.
[0] =>
[one] => [val1]
[two] => [val2]
[three] => [val3]
[four] => [val4]
[0] =>
[one] => [val1]
[two] => [val2]
[three] => [val3]
[four] => [val4]
~I tried array push and couldnt get it sorted, So what i did was this.
while ($row = mysql_fetch_assoc($query)) {
$row['five'] = str_replace('.','',$row['place']);
$results[] = $row;
}
resulting in
[0] =>
[one] => [val1]
[two] => [val2]
[three] => [val3]
[four] => [val4]
[five] => [val5]
[0] =>
[one] => [val1]
[two] => [val2]
[three] => [val3]
[four] => [val4]
[five] => [val5]