PHP array_merge() function - php

Question

I have some problems during working with arrays using array_merge function. Here an example:
First example:
$first = array('01' => 1, '03' => 73);
$second = array('14'=>11, '15' => 23);
var_dump(array_merge($first, $second));
Result is:
array(4) { ["01"]=> int(1) ["03"]=> int(73) [0]=> int(11) [1]=> int(23) }
Expected:
array(4) { ["01"]=> int(1) ["03"]=> int(73) [14]=> int(11) [15]=> int(23) }
Second example:
$first = array('01'=>3, '03'=>10);
$second = array('05'=>44, '07'=>3);
var_dump(array_merge($first,$second));
Result is(as expected):
array(4) { ["01"]=> int(3) ["03"]=> int(10) ["05"]=> int(44) ["07"]=> int(3) }
Third example:
var_dump(array_merge(array("somekey"=> array("some value"))));
Result is(as expected):
array(1) { ["somekey"]=> array(1) { [0]=> string(10) "some value" } }
Fourth example:
var_dump(array_merge(array("34"=> array("some value"))));
Result is:
array(1) { [0]=> array(1) { [0]=> string(10) "some value" } }
Expected:
array(1) { [0]=> array(1) { ["34"]=> string(10) "some value" } }
var_dump(array_merge(array("34"=> array("some value"))));
As you can see from third and fourth examples I set string for keys but the result was not as expected.
What is wrong or incorrect of understanding?
Thanks for helping.
Edited. Why (example first and second) the result is different, but the keys are string and consist of only with digest?

Answer 1

Quoting from the manual:
If the input arrays have the same string keys, then the later value
for that key will overwrite the previous one. If, however, the arrays
contain numeric keys, the later value will not overwrite the original
value, but will be appended.
Values in the input array with numeric keys will be renumbered with
incrementing keys starting from zero in the result array.
Keys with a leading zero are being treated as strings, while numeric keys without a leading zero are being treated as numeric
If you want to retain the keys exactly as they are:
$first = array('01' => 1, '03' => 73);
$second = array('14'=>11, '15' => 23);
var_dump(
array_combine(
array_merge(
array_keys($first), array_keys($second)
),
array_merge(
$first, $second
)
)
);
as long as keys are unique between $first and $second

Answer 2

Definition : Merges the elements of one or more arrays together so that the values of one are appended to the end of the previous one. It returns the resulting array.
If the input arrays have the same string keys, then the later value for that key will overwrite the previous one. If, however, the arrays contain numeric keys, the later value will not overwrite the original value, but will be appended.
Values in the input array with numeric keys will be renumbered with incrementing keys starting from zero in the result array.
INPUT
<?php
$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
$result = array_merge($array1, $array2);
print_r($result);
?>
OUTPUT
Array
(
[color] => green
[0] => 2
[1] => 4
[2] => a
[3] => b
[shape] => trapezoid
[4] => 4
)
Hope it helps:)

Answer 3

Try array_merge() like below:-
$first = array('01' => 1, '03' => 73);
$second = array('14'=>11, '15' => 23);
$output = array_merge($first, $second);
print_r($output);
EDIT:-
$first = array('01' => 1, '03' => 73);
$second = array('14'=>11, '15' => 23);
$output = $first + $second;
print_r($output);