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
(PHP 4, PHP 5, PHP 7, PHP 8)
array_merge — 合并一个或多个数组
$...
= ?
) : array将一个或多个数组的单元合并起来,一个数组中的值附加在前一个数组的后面。返回作为结果的数组。
如果输入的数组中有相同的字符串键名,则该键名后面的值将覆盖前一个值。然而,如果数组包含数字键名,后面的值将 不会 覆盖原来的值,而是附加到后面。
如果输入的数组存在以数字作为索引的内容,则这项内容的键名会以连续方式重新索引。
...
要合并的数组。
返回合并后的结果数组。如果参数为空,则返回空 array。
版本 | 说明 |
---|---|
7.4.0 | 允许不带参数调用,之前版本至少需要一个参数。 |
Example #1 array_merge() 示例
<?php
$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
$result = array_merge($array1, $array2);
print_r($result);
?>
以上例程会输出:
Array ( [color] => green [0] => 2 [1] => 4 [2] => a [3] => b [shape] => trapezoid [4] => 4 )
Example #2 Simple array_merge() 示例
<?php
$array1 = array();
$array2 = array(1 => "data");
$result = array_merge($array1, $array2);
?>
别忘了数字键名将会被重新编号!
Array ( [0] => data )
如果你想完全保留原有数组并只想新的数组附加到后面,可以使用
+
运算符:
<?php
$array1 = array(0 => 'zero_a', 2 => 'two_a', 3 => 'three_a');
$array2 = array(1 => 'one_b', 3 => 'three_b', 4 => 'four_b');
$result = $array1 + $array2;
var_dump($result);
?>
第一个数组的键名将会被保留。在两个数组中存在相同的键名时,第一个数组中的同键名的元素将会被保留,第二个数组中的元素将会被忽略。
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" }
Example #3 array_merge() 合并非数组的类型
<?php
$beginning = 'foo';
$end = array(1 => 'bar');
$result = array_merge((array)$beginning, (array)$end);
print_r($result);
?>
以上例程会输出:
Array ( [0] => foo [1] => bar )
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
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