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array_merge

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

array_mergeCombina um ou mais arrays

Descrição

array_merge(array $array1, array $... = ?): array

Funde os elementos de dois ou mais arrays de forma que os elementos de um são colocados no final do array anterior. Retorna o array resultante da fusão.

Se os arrays dados têm as mesmas chaves string, então o último valor para uma chave irá sobrescrever o valor anterior. Se, no entanto, os arrays tem as mesmas chaves numéricas, o último valor para uma chave não sobrescreverá o valor original, e sim adicionado ao array resultante.

Se apenas uma array é dada e a array é indexada numericamente, as chaves são reindexadas de uma maneira continua.

Parâmetros

array1

O array inicial para fundir.

...

A lista variável de arrays para fundir recursivamente.

Valor Retornado

Retorna o array resultante.

Exemplos

Exemplo #1 Exemplo de array_merge()

<?php
$array1 
= array("cor" => "vermelho"24);
$array2 = array("a""b""cor" => "verde""forma" => "trapezoide"4);
$result array_merge($array1$array2);
print_r($result);
?>

O exemplo acima irá imprimir:

Array
(
    [cor] => verde
    [0] => 2
    [1] => 4
    [2] => a
    [3] => b
    [forma] => trapezoide
    [4] => 4
)

Exemplo #2 Exemplo simples de array_merge()

<?php
$array1 
= array();
$array2 = array(=> "data");
$result array_merge($array1$array2);
?>

Não esqueça que as chaves numéricas serão reordenadas!

Array
(
    [0] => data
)

Se você deseja apenas adicionar os elementos do segundo array no primeiro, sem sobrescrever os elementos e sem causar a reindexação, utilize o operador +:

<?php
$array1 
= array(=> 'zero_a'=> 'two_a'=> 'three_a');
$array2 = array(=> 'one_b'=> 'three_b'=> 'four_b');
$result $array1 $array2;
var_dump($result);
?>

As chaves do primeiro array são preservados. Se uma chave existir em dois arrays, então o elemento do primeiro array será preservado e o elemento de mesma chave no segundo array será descartado.

array(5) {
  [0]=>
  string(6) "zero_a"
  [2]=>
  string(5) "two_a"
  [3]=>
  string(7) "three_a"
  [1]=>
  string(5) "one_b"
  [4]=>
  string(6) "four_b"
}

Exemplo #3 array_merge() com tipos não array

<?php
$beginning 
'foo';
$end = array(=> 'bar');
$result array_merge((array)$beginning, (array)$end);
print_r($result);
?>

O exemplo acima irá imprimir:

    Array
    (
        [0] => foo
        [1] => bar
    )

Veja Também

add a note

User Contributed Notes 6 notes

up
292
Julian Egelstaff
13 years ago
In some situations, the union operator ( + ) might be more useful to you than array_merge.  The array_merge function does not preserve numeric key values.  If you need to preserve the numeric keys, then using + will do that.

ie:

<?php

$array1
[0] = "zero";
$array1[1] = "one";

$array2[1] = "one";
$array2[2] = "two";
$array2[3] = "three";

$array3 = $array1 + $array2;

//This will result in::

$array3 = array(0=>"zero", 1=>"one", 2=>"two", 3=>"three");

?>

Note the implicit "array_unique" that gets applied as well.  In some situations where your numeric keys matter, this behaviour could be useful, and better than array_merge.

--Julian
up
23
ChrisM
11 months ago
I wished to point out that while other comments state that the spread operator should be faster than array_merge, I have actually found the opposite to be true for normal arrays. This is the case in both PHP 7.4 as well as PHP 8.0. The difference should be negligible for most applications, but I wanted to point this out for accuracy.

Below is the code used to test, along with the results:

<?php
$before
= microtime(true);

for (
$i=0 ; $i<10000000 ; $i++) {
   
$array1 = ['apple','orange','banana'];
   
$array2 = ['carrot','lettuce','broccoli'];
   
   
$array1 = [...$array1,...$array2];
}

$after = microtime(true);
echo (
$after-$before) . " sec for spread\n";

$before = microtime(true);

for (
$i=0 ; $i<10000000 ; $i++) {
   
$array1 = ['apple','orange','banana'];
   
$array2 = ['carrot','lettuce','broccoli'];
   
   
$array1 = array_merge($array1,$array2);
}

$after = microtime(true);
echo (
$after-$before) . " sec for array_merge\n";
?>

PHP 7.4:
1.2135608196259 sec for spread
1.1402177810669 sec for array_merge

PHP 8.0:
1.1952061653137 sec for spread
1.099925994873 sec for array_merge
up
6
Andreas Hofmann
1 year ago
In addition to the text and Julian Egelstaffs comment regarding to keep the keys preserved with the + operator:
When they say "input arrays with numeric keys will be renumbered" they MEAN it. If you think you are smart and put your numbered keys into strings, this won't help. Strings which contain an integer will also be renumbered! I fell into this trap while merging two arrays with book ISBNs as keys. So let's have this example:

<?php
    $test1
['24'] = 'Mary';
   
$test1['17'] = 'John';

   
$test2['67'] = 'Phil';
   
$test2['33'] = 'Brandon';

   
$result1 = array_merge($test1, $test2);
   
var_dump($result1);

   
$result2 = [...$test1, ...$test2];    // mentioned by fsb
   
var_dump($result2);
?>

You will get both:

array(4) {
  [0]=>
  string(4) "Mary"
  [1]=>
  string(4) "John"
  [2]=>
  string(4) "Phil"
  [3]=>
  string(7) "Brandon"
}

Use the + operator or array_replace, this will preserve - somewhat - the keys:

<?php
    $result1
= array_replace($test1, $test2);
   
var_dump($result1);

   
$result2 = $test1 + $test2;
   
var_dump($result2);
?>

You will get both:

array(4) {
  [24]=>
  string(4) "Mary"
  [17]=>
  string(4) "John"
  [67]=>
  string(4) "Phil"
  [33]=>
  string(7) "Brandon"
}

The keys will keep the same, the order will keep the same, but with a little caveat: The keys will be converted to integers.
up
9
fsb at thefsb dot org
2 years ago
We no longer need array_merge() as of PHP 7.4.

    [...$a, ...$b]

does the same as

    array_merge($a, $b)

and can be faster too.

https://wiki.php.net/rfc/spread_operator_for_array#advantages_over_array_merge
up
0
JoshE
8 months ago
Not to contradict ChrisM's test, but I ran their code example and I got very different results for PHP 8.0.

Testing PHP 8.0.14
1.4955070018768 sec for spread
4.4120140075684 sec for array_merge
up
-1
php at k dot ull dot at
1 month ago
Merge two arrays and retain only unique values.
Append values from second array.
Do not care about keys.

$array1 = [
    0 => 'apple',
    1 => 'orange',
    2 => 'pear',
];

$array2 = [
    0 => 'melon',
    1 => 'orange',
    2 => 'banana',
];

$result = array_keys(
    array_flip($array1) + array_flip($array2)
);

Result:
[
  [0] => "apple",
  [1] => "orange",
  [2] => "pear",
  [3] => "melon",
  [4] => "banana",
}
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