以字符序列的形式从键盘输入语法正确的、不含变量的整数表达式，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求值，并打印求值过程中运算符栈、操作数栈的变化过程。-In the form of a sequence of characters from the keyboard input grammatically correct, non-integer variable expression, using the given operator precedence relations,