如何防止重新编号assoc_merge的结果？

Question

I use array_merge function for merging two arrays. In most case it works properly

$x = array_merge(array('a' => 'x', 'b' => 'x'), array('b' => 'y', 'c' => 'y'));
var_dump($x);

// array(3) { ["a"]=> string(1) "x" ["b"]=> string(1) "y" ["c"]=> string(1) "y" }

But for numeric case it returns unexpected result

$x = array_merge(array('1' => 'x', '2' => 'x'), array('2' => 'y', '3' => 'y'));
var_dump($x);

// array(4) { [0]=> string(1) "x" [1]=> string(1) "x" [2]=> string(1) "y" [3]=> string(1) "y" }

How to prevent renumbering of indexes? There is way to merge two arrays by base php functions without renumbering of numeric indexes?

Answer 1

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.

so, instead use array_replace.