1、　　设计一个简易的计算器，可以进行简单的四则运算：加、减、乘、除等（限于十进制下）

程序要求：

（1）接收终端输入的某种四则运算式，例如“2*（3+1）”，当用户敲回车时，即给出运算结果，显示为：“2*（3+1）=8”

（2）运算符号定为：“+”，“-”，“*”，“/”。

-1, design a simple calculator that can perform simple arithmetic: addition, subtraction, multiplication, division, etc. (limited to the next decimal) program requirements: (1) to receive a four terminal input expressions, such as " 2* ( 3+1) " , when the user hit Enter, that gives the operator the results appear as:"　2* (3+1) = 8 " (2) operator symbols as :" +" ," -" ," *" ," /" 。