C++实现任意表达式的四则运算。数据结构与算法中双链表的使用。在VC2008或2010中完成，可转换到其他编辑器中运行。-C++, arbitrary arithmetic expressions. Data structures and algorithms used in the double-linked list. Completed in the VC2008 or 2010, can be converted to another editor to run.