我不知道如何让displayGPA（）干净地处理一个零分区

Question

#!/usr/bin/env python3

class Student:
    def __init__(self, name, number):
        self.name = name
        self.number = number
        self.courses = {}

    def displayStudent(self):
        return 'Student Name: ' + self.name + '\n' + 'Student Number: ' + str(self.number)

    def addGrade(self, course, grade):
        self.courses[course] = grade

    def displayGPA(self):
        if len(self.courses) == 0:
            errormsg  = print('Wrong Input')
            return errormsg

        else:
            gpa = 0.0
            for course in self.courses.keys():
                gpa = gpa + self.courses[course]
            return 'GPA of student ' + self.name + ' is ' + str(gpa / len(self.courses))


    def displayCourses(self):
        return [k for k in self.courses.keys() if self.courses[k] > 0]


if __name__ == '__main__':
    # Create first student object and add grades for each class
    student1 = Student('John', '013454900')
    student1.addGrade('uli101', 1.0)
    student1.addGrade('ops235', 2.0)
    student1.addGrade('ops435', 3.0)

    # Create second student object and add grades for each class
    student2 = Student('Jessica', '123456')
    student2.addGrade('ipc144', 4.0)
    student2.addGrade('cpp244', 3.5)
    student2.addGrade('cpp344', 0.0)

    # Display information for student1 object
    print(student1.displayStudent())
    print(student1.displayGPA())
    print(student1.displayCourses())

    # Display information for student2 object
    print(student2.displayStudent())
    print(student2.displayGPA())
    print(student2.displayCourses())

问题在于displayGPA()可能被零除（ZeroDivisionError），如果没有课程添加到字典或添加到字典的分数是0.0浮动的

Answer 1

您可以尝试decimal模块：

from decimal import *

setcontext(ExtendedContext)

value = 123 / Decimal(0)    # value is now Decimal('Infinity')
print(str(float(value)))

输出：

'inf'