算符优先文法 -Operator Prior operator priority grammar grammar

现在要求以字符序列的形式从终端输入语法正确的、不含变量的表达式，利用给定的算符优先关系，实现对算术四则混合运算表达式的求值，并演示在求值过程中运算栈、操作数栈、输入字符和主要操作的变化过程-Now in the form required character sequences from input terminal of the correct grammar, do not contain variables by the operator is given priority to, the