Add array to array php

Question

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

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Description
Return Values
How do I add an array to another array in PHP?
What is array_push in PHP?
Can you add arrays in PHP?
How do I add one array to another?

array_push — Push one or more elements onto the end of array

Description

array_push(array &$array, mixed ...$values): int

repeated for each passed value.

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 differed from the $var[] behaviour where a new array was created, prior to PHP 7.1.0.

Parameters

array

The input array.

values

The values to push onto the end of the array.

Return Values

Returns the new number of elements in the array.

Changelog

Version	Description
7.3.0	This function can now be called with only one parameter. Formerly, at least two parameters have been required.

Examples

Example #1 array_push() example

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

The above example will output:

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

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 ]

willdemaine at gmail dot com ¶

14 years ago

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:

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

raat1979 at gmail dot com ¶

6 years ago

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...)

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 "