$array = array("a" => "apple", "B" => "banana", "c" => "cherry");
$result = array_change_key_case($array, CASE_UPPER);
print_r($result);
echo "\n";
$array = array("a" => "apple", "b" => "banana", "c" => "cherry");
$firstKey = array_key_first($array);
echo $firstKey;
echo "\n\n";
$array = array("a" => "apple", "b" => "banana", "c" => "cherry");
$lastKey = array_key_last($array);
echo $lastKey;
echo "\n\n";
$array1 = array("Dog", "Cat", "Horse");
$array2 = array("Pluto", "Garfield", "Hercules");
array_multisort($array1, $array2);
print_r($array1);
print_r($array2);
echo "\n";
$array1 = array("red", "green");
$array2 = array("blue", "yellow");
$result = array_replace($array1, $array2);
print_r($result);
echo "\n";
$array = array("red", "green", "blue");
$result = array_reverse($array);
print_r($result);
echo "\n";
$array = array("a", "b", "c", "d", "e");
$slice = array_slice($array, 2);
print_r($slice);
echo "\n";
$array = array("red", "green", "blue", "yellow");
array_splice($array, 1, 2, array("black", "maroon"));
print_r($array);
echo "\n";
$array1 = array("a" => "red", "b" => "green", "c" => "blue");
$array2 = array("a" => "yellow", "b" => "black");
$result = array_diff_key($array1, $array2);
print_r($result);
echo "\n";
$array = array_fill(0, 5, "banana");
print_r($array);
echo "\n";
$keys = array("foo", "bar", "baz");
$result = array_fill_keys($keys, "banana");
print_r($result);
echo "\n";
$array1 = array("a" => "red", "b" => "green", "c" => "blue");
$array2 = array("a" => "yellow", "b" => "black");
$result = array_intersect_key($array1, $array2);
print_r($result);
echo "\n";
$array1 = array("a" => "red", "b" => "green", "c" => "blue");
$array2 = array("a" => "yellow", "b" => "black");
$result = array_uintersect($array1, $array2, "strcasecmp");
print_r($result);
echo "\n";