用算符优先法对算术表达式求值的过程。要求以字符序列的形式从终端输入语法正确的、不含变量的整数表达式。实现对算术四则混合运算表达式的求值，并在求值中运算符栈、运算数栈、输入字符和主要操作的变化过程。-Operator priority method with arithmetic expression evaluation process. Request to form a sequence of characters from the terminal input grammar correc