实验要求

要求实现语法分析程序的以下功能：

把表达式首先经过词法分析形成二元式记号提供给语法分析程序

如果符合语法要求，形成一个语法树

实验三 算符优先分析

如果出现错误，指出错误的位置和类型

把语法树按照树的前序遍历的形式把所有的结点打印输出

按照某种规则计算出表达式的值-Experimental requirements requirements the parser following features: the expression first formed after the lexical analysis binary notation available to the parser grammatically form a syntax tree experiment operator priority analysis If an error occurs, that error The location and type of the syntax tree in accordance with the pre-order traversal of the tree in the form of all the nodes printout according to certain rules to calculate the value of the expression