分数计算器及测试程序，具有对输入的运算进行“+，-，*，/”的功能

（1）完成计算器程序，对main函数的结构进行改进，要求有详细的菜单选项界面，用户不选择退出就可以反复运算。

（2）完善程序，改为多操作数基本四则运算，遇#停止。

（3）增加函数，完成四则混合运算，注意算法要考虑运算符的优先级，对应增加主菜单选项。

（4）增加语句使四则运算具有测试功能，即计算机能够 自动出题，并要求用户计算，同时计算机判断用户计算的对错并打分，要求十题一个单元，每题一个运算符，参与运算的分子分母均为一位数，运算符包括加，减，乘，除及大于小于等运算符。-Fractional calculator and test procedures, with the input of the operation　+,-,*, /　function

(1) to complete the calculator program, the structure of the main function to improve the requirements of a detailed menu options interface, users do not choose to exit can be repeated operation.

(2) to improve the program, to multi operand four basic arithmetic, in# stop.

(3) increase in function, the completion of four hybrid operation, pay attention to consider the operator priority algorithm, the corresponding increase in the main menu options.

(4) increase a statement the four operations with testing, in which a computer can questions automatically, and requires the user to calculate. At the same time, the computer to determine the user to calculate the right　wrong and scoring, ten questions a unit, each item with an operator in operation of the numerator and denominator are a digit, operators including addition, subtraction, multiplication, division and greater than the other opera