I've seen the following often lately and I'm wondering what it does? I can't seem to find it in the PHP manual.
$arr1 = array('key' => 'value1');
$arr2 = array('key' => 'value2');
$arr1 += $arr2;
Is it similar to an array_merge?
I know what the following does, but I don't understand what it does when working with an array:
$var1 = 1;
$var2 = 2;
$var1 += $var2;
echo $var1; // 3
$arr1 += $arr2 is short for $arr1 = $arr1 + $arr2.
The + array operator does the following:
$arr1 and $arr2, except for the next condition.$arr1 will be present.$arr2 will be after those of $arr1.This is different from array_merge, which:
$arr1 and $arr2, except for the next condition.$arr2 will be present.$arr1, and then moving to the elements of $arr2.$arr2 will be after those of $arr1, except the string elements, which will be in the position of the first array in which they appear.Example:
<?php
$arr1 = array(1 => 'value1.1', 10 => 'value1.2', 's' => 'value1.s');
$arr2 = array(1 => 'value2', 2=> 'value2.2', 's' => 'value2.s');
var_dump(array_merge($arr1,$arr2));
$arr1 += $arr2;
var_dump($arr1);
Result (edited for clarity):
array(5) {
[0] => string(8) "value1.1"
[1] => string(8) "value1.2"
["s"] => string(8) "value2.s"
[2] => string(6) "value2"
[3] => string(8) "value2.2"
}
array(4) {
[1] => string(8) "value1.1"
[10] => string(8) "value1.2"
["s"] => string(8) "value1.s"
[2] => string(8) "value2.2"
}
The + operator in PHP when applied to arrays does the job of array UNION.
$arr += array $arr1;
effectively finds the union of $arr and $arr1 and assigns the result to $arr.
The + operation between two arrays acts like a UNION.
One of the differences between array_merge(), and the sum of two arrays is evident in the following snippets. (See also https://3v4l.org/TcNBF.)
$array1 = array();
$array2 = array(1 => "data");
$result = array_merge($array1, $array2);
The index in $result will be 0.
$array1 = array();
$array2 = array(1 => "data");
$result = $array1 + $array2;
The index is not changed; the index is still 1.