问题描述：一个算术表达式是由操作数(operand)、运算符(operator)和界限符(delimiter)组成的。假设操作数是正整数，运算符只含加减乘除等四种运算符，界限符有左右括号和表达式起始、结束符“#”，如：#（7+15）*（23-28/4）#。引入表达式起始、结束符是为了方便。编程利用“算符优先法”求算术表达式的值。

基本要求：从键盘读入一个合法的算术表达式，输出正确的结果；显示输入序列和栈的变化过程，操作数类型扩充到实数。

-Problem Descr iption: An arithmetic expression is an operand (operand), operator (operator) and boundary character (delimiter) composition. Assuming a positive integer operands, operators, containing only addition, subtraction and other four operators, boundary character has left and right parentheses and expressions start and end symbol　# , such as:# (7+ 15)* (23-28/4)#. Introducing expressions start and end character is for convenience. Programming using the　operator precedence　Evaluate arithmetic expressions.

Basic requirements: reads a legitimate arithmetic expressions, output the correct result　the keyboard　display change process sequence and stack input operand types expanded to real numbers.