Get the first element of an array

Original answer, but costly (O(n)):

array_shift(array_values($array));

In O(1):

array_pop(array_reverse($array));

Other use cases, etc...

If modifying (in the sense of resetting array pointers) of $array is not a problem, you might use:

reset($array);

This should be theoretically more efficient, if a array "copy" is needed:

array_shift(array_slice($array, 0, 1));

With PHP 5.4+ (but might cause an index error if empty):

array_values($array)[0];

As Mike pointed out (the easiest possible way):

$arr = array( 4 => 'apple', 7 => 'orange', 13 => 'plum' )
echo reset($arr); // Echoes "apple"

If you want to get the key: (execute it after reset)

echo key($arr); // Echoes "4"

From PHP's documentation:

mixed reset ( array &$array );

Description:

reset() rewinds array's internal pointer to the first element and returns the value of the first array element, or FALSE if the array is empty.

$first_value = reset($array); // First element's value
$first_key = key($array); // First element's key