Python：使用学分和成绩计算班级的 GPA

Question

我非常接近这段代码，我需要弄清楚如何将多个等级作为参数。它需要一个完美的，但我的代码是这样写的，所以它会不断地获取成绩和学分，直到没有输入任何内容。但事实并非如此。

到目前为止我的代码：

#! /usr/bin/python3
# gpa.py
#    Program to take credits and grades and return calculated GPA

class Student:

def __init__(self, hours, qpoints, credits):
    self.hours = float(hours)
    self.qpoints = float(qpoints)

def getName(self):
    return self.name

def getHours(self):
    return self.hours

def getQPoints(self):
    return self.qpoints

def gpa(self):
    return self.qpoints/self.hours

def addGrade(self, gradePoint, credits):
    self.hours += credits
    self.qpoints += credits*gradePoint

def addLetterGrade(self, grade):
    total = 0
    for i in grade(A,B,C,D,E,F):
        if grade == 'A':
                     total = total + 4.0
        elif grade == 'A-':
                     total = total + 3.7
        elif grade == 'B+':
                     total = total + 3.3
        elif grade == 'B':
                     total = total + 3.0
        elif grade == 'B-':
                     total = total + 2.7
        elif grade == 'C+':
                     total = total + 2.3
        elif grade == 'C':
                     total = total + 2.0
        elif grade == 'C-':
                     total = total + 1.7
        elif grade == 'D+':
                     total = total + 1.3
        elif grade == 'D':
                     total = total + 1.0
        elif grade == 'E':
                     total = total + 0.0
        elif grade == 'F':
                     total = total + 0.0



def main():
    grade = input('Enter grade for next course, or type done finish: ')
    credits = input('Enter number of credit hours for this course: ')
    error_float = 'error: expected a floating-point number'
# make a new Student object
    students = Student('students', 0.0, 0.0)

# user-feedback loop
    while 1:
    # prompt user to enter a grade
        grade_str = input(grade)
    # quit if no grade is entered
        if grade_str.strip() == 'done':
            break

        try:
        # convert input to a floating-point value
            grade = float(grade_str)
        except ValueError:
        # if input cannot be converted, restart feedback loop
            print(error_float)
            continue

    # prompt user to enter the number of credits
        credits_str = input(credits).strip()
        try:
        # convert input to a floating-point value
            credits = float(credits_str)
        except ValueError:
        # if input cannot be converted, restart feedback loop
            print(error_float)
            continue

    # update the student's grades
        students.addGrade(grade, credits)

# after user has entered all grades, compute the cumulative GPA
    if students.getHours() == 0.0:
    # can't compute GPA if hours = 0
        print('*** zero credit hours recorded')
    else:
    # otherwise, output cumulative GPA and finish
        print('*** final GPA =', students.gpa())

if __name__ == '__main__':
    main()

Answer 1

students = Student('students', 0.0, 0.0)

但是在 init 中你得到了：

def __init__(self, hours, qpoints, credits):
    self.hours = float(hours)

所以你给它一个字符串而不是 int/float...并且你尝试将它转换为 float， 失败了

students = Student(0.0, 0.0, 0)

或者在 init:

中输入名称或其他内容

def __init__(self, name, hours, qpoints, credits):

Answer 2

你可以试试这个方法...

#! /usr/bin/python3
# gpa.py
#    Program to take credits and grades and return calculated GPA

class Student:
    def __init__(self, hours, qpoints, credits):
        self.hours = float(hours)
        self.qpoints = float(qpoints)

    def getName(self):
        return self.name

    def getHours(self):
        return self.hours

    def getQPoints(self):
        return self.qpoints

    def gpa(self):
        return self.qpoints/self.hours

    def addGrade(self, gradePoint, credits):
        self.hours += credits
        self.qpoints += credits*gradePoint

    def addLetterGrade(self, grade):
        total = 0
        for i in grade(A,B,C,D,E,F):
            if grade == 'A':
                total = total + 4.0
            elif grade == 'A-':
                total = total + 3.7
            elif grade == 'B+':
                total = total + 3.3
            elif grade == 'B':
                total = total + 3.0
            elif grade == 'B-':
                total = total + 2.7
            elif grade == 'C+':
                total = total + 2.3
            elif grade == 'C':
                total = total + 2.0
            elif grade == 'C-':
                total = total + 1.7
            elif grade == 'D+':
                total = total + 1.3
            elif grade == 'D':
                total = total + 1.0
            elif grade == 'E':
                total = total + 0.0
            elif grade == 'F':
                total = total + 0.0



def main():
    grade = input('Enter grade for next course, or type done finish: ')
    credits = input('Enter number of credit hours for this course: ')
    error_float = 'error: expected a floating-point number'
# make a new Student object
#     students = Student('students', 0.0, 0.0) # This is wrong declaration because you initialised "def __init__(self, hours, qpoints, credits): "
    students = Student(0.0, 0.0, 0.0)

# user-feedback loop
    while 1:
    # prompt user to enter a grade
        grade_str = input(grade)
    # quit if no grade is entered
        if grade_str.strip() == 'done':
            break

        try:
        # convert input to a floating-point value
            grade = float(grade_str)
        except ValueError:
        # if input cannot be converted, restart feedback loop
            print(error_float)
            continue

    # prompt user to enter the number of credits
        credits_str = input(credits).strip()
        try:
        # convert input to a floating-point value
            credits = float(credits_str)
        except ValueError:
        # if input cannot be converted, restart feedback loop
            print(error_float)
            continue

    # update the student's grades
        students.addGrade(grade, credits)

# after user has entered all grades, compute the cumulative GPA
    if students.getHours() == 0.0:
    # can't compute GPA if hours = 0
        print('*** zero credit hours recorded')
    else:
    # otherwise, output cumulative GPA and finish
        print('*** final GPA =', students.gpa())

if __name__ == '__main__':
    main()