【DAY.1】PHP如何得到数组最后元素的key?

1.array_keys(end($arr))

	$array = array(
			'one'=>1,
			'two'=>2,
			'three'=>3,
			'four'=>4,
		);
	$arr = array_keys($array);
	var_dump(end($arr));

2.array_pop(end($arr))

	$array = array(
			'one'=>1,
			'two'=>2,
			'three'=>3,
			'four'=>4,
		);
	$arr = array_keys($array);
	var_dump(array_pop($arr));

3.foreach()

	$array = array(
			'one'=>1,
			'two'=>2,
			'three'=>3,
			'four'=>4,
		);
	foreach($array as $key => $value){
		$temp = $key;
	}
	var_dump($temp)

4.array_slice

	$array = array(
			'one'=>1,
			'two'=>2,
			'three'=>3,
			'four'=>4,
		);
	$arr = array_slice($array,-1,1,true);
	var_dump(key($arr));