1．本程序主要的功能是利用链表将用户输入的任意精度中缀表达式转换成后缀表达式，为了以便于区分数据和操作符，数据间用下划线将它们区分开来，并且计算出此表达式的值。



2．需要注意的是：此程序所叙述的四则运算是狭义的，并没有显式的要求用户以中括弧“[]”或者是大括弧“{}”进行输入,因为这样会大大的加大程序的代码量，为了简便起见，同时又为了实现四则混合运算的功能，只要用户将含有中括弧或者是大括弧的地方均以小括弧表示即可。-1. This program is the main function of the use of linked lists of user input to the arbitrary precision converted into ordinary expression suffix expression, in order to distinguish between data and operator, data will be used as an underscore to separate them, and calculate the value of this expression. 2. Note : This procedure described by the four operation is narrow, and no explicit demands to which users brackets "[]" or large bracket "()" for the importation, because it will greatly increase the volume of procedures code, for the sake of simplicity, but also to achieve four mixed computing functions, as long as the user which contains a large bracket, or brackets in both small brackets can be expressed.