Question

I have an array:

$array = array('a' => 'val1', 'b' => 'val2', 'c' => 'val3', 'd' => 'val4');

How do I swap any two keys round so the array is in a different order? E.g. to produce this array:

$array = array('d' => 'val4', 'b' => 'val2', 'c' => 'val3', 'a' => 'val1');

Thanks :).

Answer 1

I thought there would be really simple answer by now, so I’ll throw mine in the pile:

// Make sure the array pointer is at the beginning (just in case)
reset($array);

// Move the first element to the end, preserving the key
$array[key($array)] = array_shift($array);

// Go to the end
end($array);

// Go back one and get the key/value
$v = prev($array);
$k = key($array);

// Move the key/value to the first position (overwrites the existing index)
$array = array($k => $v) + $array;

This is swapping the first and last elements of the array, preserving keys. I thought you wanted array_flip() originally, so hopefully I’ve understood correctly.

Demo: http://codepad.org/eTok9WA6