1、实现算术表达式的求值运算，程序通过键盘输入一个表达式，通过运算得到表达式的值，并在显示器上输出完整的表达式及其值；

2、程序实现时，采用栈数据结构

3、表达式以字符串的形式输入；

4、表达式中包括的基本运算符有加、减、乘、除（分别用+、-、*、、表示），表达式中包括括号的处理，括号可以嵌套；表达式中的数字可以是整数，也可以是小数-1, and the evaluation of arithmetic operations, the program through keyboard input an expression, obtained by computing the value of the expression and display the full expression of the value of output　2, program implementation, the use of the stack data structure 3, the expression as a string input　4 expression, including the basic operators are add, subtract, multiply and divide (respectively+,-,*,, said), the expression including the handling of parentheses, Parentheses can be nested　expressions can be integer numbers, can also be fractional