几种快速排序的方法，对int类型数组排序，对char类型数组排序，对double类型数组排序，对结构体一、二级排序，对字符串进行排序，计算几何中求凸包的cmp-Several methods of quick sort, sort array of type int, the type of char array to sort, sort array of double type of the structure of primary and secondary sort, sort of s