以字符序列的形式从终端输入语法正确的，不含变量的整数表达式。利用算符优先关系，实现对算术四则混合运算表达式的求值，并演示在求值中运算符栈、运算数栈、输入字符和主要操作的变化过程。-In the form of character sequence from the terminal input grammar correctly, do not contain the variables of the integer expression. Use of operator of prior relation, and to realize the four mixed operation expression of the arithmetic evaluated, and the presentation is evaluated operators stack, operation in several stack, input character and the change of the main operation process.