Merging associative arrays in PHP

Pontus — Mon, 19 Oct 2009 22:16:50 +0000

It’s nice when serendipity is your friend! I was porting my Bitly class from Pike to PHP – I know there’s probably a hundred PHP classes already out there, but mine is better coded – and noted by accident that I had used some Pike syntax in my PHP class but it was working anyway. So what was I doing? In Pike there’s separate data type for associative arrays called mapping. In Pike, in general, when merging two objects you just join them with a + sign. Thus merging two mappings you do like


mapping m1 = ([ "key1" : "Value 1", "key2" : "Value 2" ]);
mapping m2 = ([ "key3" : "Value 3" ]);

write("My mapping: %O\n", m1 + m2);
//> My mapping: ([ /* 3 elements */
//>   "key1": "Value 1",
//>   "key2": "Value 2",
//>   "key3": "Value 3"
//> ])

And I noted that I had done the same thing in PHP and the result was perfectly valid:


$a1 = array("key1" => "Value 1", "key2" => "Value 2");
$a2 = array("key3" => "Value 3");

echo "My mapping: ";
print_r($a1 + $a2);
//> My mapping: Array
//> (
//>     [key1] => Value 1
//>     [key2] => Value 2
//>     [key3] => Value 3
//> )

This method doesn’t work on flat array though so there you’ll still have to use array_merge(), but pretty nice anyway.

And oh, the PHP Bitly class will be part of the new PLib release once done!

Pontus Östlund » Serendipity

Merging associative arrays in PHP