第5次作业--四则运算

GitHub项目地址： https://github.com/ZJW9633/hello-word/blob/master/ElArith.py

PSP

PSP2.1	Personal Software Process Stages	预估耗时(分钟)	实际耗时(分钟)
Planning	计划	10	23
Estimate	估计这个任务需要多少时间	15	/
Development	开发	40	60
Analysis	需求分析(包括学习新技术)	40	60
Design Spec	生成设计文档	/	/
Design Review	设计复审(和同事审核设计文档)	20	25
Coding Standard	代码规范(为目前的开发制定合适的规范)	10	10
Design	具体设计	20	25
Coding	具体编码	60	120
Code Review	代码复审	15	20
Test	测试(自我测试,修改代码,提交修改)	25	25
Reporting	报告	25	60
Test Report	测试报告	40	45
Size Measurement	计算工作量	10	10
Postmortem & Process Improvement Plan	事后总结,并提出过程改进计划	20	25
合计		325	460

项目要求

参与运算的操作数(operands)除了100以内的整数以外，还要支持真分数的四则运算。操作数必须随机生成。
运算符(operators)为 +, −, ×, ÷ 运算符的种类和顺序必须随机生成。
要求能处理用户的输入，并判断对错，打分统计正确率。
使用参数控制生成题目的个数。

解题思路：

定义一个函数用于随机生成随机长度的算式
把字符串型的算式转换为逆波兰式(RPN，也称后缀表达式)
再把后缀表达式利用栈结构计算出结果
最后再与用户的输入做比较

重点难点：

计算结果为负数的情况
分数的表示和计算

难点解决思路：

使用python的fractions库
分数的表示和计算

代码说明:

#算式转换形式

    def toRpn(self, question):
        self.stack = []
        s = ''
        for x in question:
            if x != '+' and x != '-' and x != '×' and x != '÷' and x != '/':
                s += x  #若为数字，直接输出
            else:  # 若为运算符，进栈
                if not self.stack:  #栈空
                    self.stack.append(x)
                else:
                    if self.this_bigger(x, self.stack[-1]):  #运算级高于栈顶元素
                        self.stack.append(x)  #直接进栈
                    else:
                        while self.stack:
                            if self.this_bigger(x, self.stack[-1]):
                                break
                            s += self.stack.pop()
                        self.stack.append(x)
        while self.stack:
            s += self.stack.pop()
        return s

代码测试

C:UsersAdministratorPycharmProjectsuntitledvenvScriptspython.exe C:/Users/Administrator/PycharmProjects/untitled/size.py
please input the num of question：10
----------the total of question is:10----------
the 1/10 question is :5×3-2+4-8×8/9=
1
Your answer is wrong !The right answer is :89/9
the 2/10 question is :5+8/9÷1×3×7/9-4=
2
Your answer is wrong !The right answer is :83/27
the 3/10 question is :7÷8-1+8×8/9-4/9×8=
3
Your answer is wrong !The right answer is :247/72
the 4/10 question is :4+6/9+5=
87/9
Your answer is wrong !The right answer is :29/3
the 5/10 question is :2÷8+7÷3×1+8=
1
Your answer is wrong !The right answer is :127/12
the 6/10 question is :0+7/9+2+7÷6÷1=
2
Your answer is wrong !The right answer is :71/18
the 7/10 question is :3/5-8÷3+1×6/7×7×1=
3
Your answer is wrong !The right answer is :59/15
the 8/10 question is :4/6÷6=
4/36
Your answer is wrong !The right answer is :1/9
the 9/10 question is :7+3-6×0÷6=

Your answer is wrong !The right answer is :10
the 10/10 question is :8÷1÷6+7×2÷5/8×7/8=
2
Your answer is wrong !The right answer is :787/480
-------------------------------------
----------you have pass 0 question----------

Process finished with exit code 0

效能分析，可用python的profile进行

结果：暂无