(PHP 5 >= 5.2.0, PHP 7)
ArrayIterator::uasort — Sort with a user-defined comparison function and maintain index association
This method sorts the elements such that indices maintain their correlation with the values they are associated with, using a user-defined comparison function.
Note:
If two members compare as equal, their relative order in the sorted array is undefined.
cmp_function
�ڵ�һ������С�ڣ����ڻ���ڵڶ�������ʱ���ñȽϺ���������Ӧ�ط���һ��С�ڣ����ڻ���� 0 ��������
û�з���ֵ��