我的程序不会放成绩

Question

对于这个作业，我们应该在 Python 中开设一门课，我们在其中输入 3 个分数，并且必须找到学生的平均成绩和成绩。它有效，但我有一个错误。当我输入一个整数（例如 73）三次时，它会显示字母等级。但是当我输入一个带小数的数字（例如 83.7）三次时，它不会显示字母等级，这就是我们需要的数字。当我输入带小数的数字时，有没有办法让它显示成绩？为什么它只适用于整数？

class grades:
    def __init__(self,name,test1,test2,test3,avg):
            self.name = name
            self.test1 = test1
            self.test2 = test2
            self.test3 = test3
            self.avg = avg

    def getName(self):
        return self.name

    def getTest1(self):
        return self.test1

    def getTest2(self):
        return self.test2

    def getTest3(self):
        return self.test3

    def getAvg(self):
        return self.avg


#main:
name = input("Enter the students name: ")
test1 = float(input("Enter the first score: "))
test2 = float(input("Enter the second score: "))
test3 = float(input("Enter the third score: "))
avg = float(test1 + test2 + test3) /3.0
grades1 = grades(name,test1,test2,test3,avg)
grades1.name
grades1.test1
grades1.test2
grades1.test3
grades1.avg
print("The student's name is:" ,grades1.name)
print(grades1.name +"'s test scores are:")
print("---------------------------:")
print("TEST1: \t\t\t",grades1.test1)
print("TEST2: \t\t\t",grades1.test2)
print("TEST3: \t\t\t",grades1.test3)
print(grades1.name +"'s average is: \t",grades1.avg)
##if avg <= 100.0 and avg >= 90.0:
##    print(name +"'s grade is: \t A")
##elif avg <= 89.0 and avg >= 80.0:
##    print(name +"'s grade is: \t B")
##elif avg <= 79.0 and avg >= 70.0:
##    print(name +"'s grade is: \t C")
##elif avg <= 69.0 and avg >= 60.0:
##    print(name +"'s grade is: \t D")
##elif avg <= 59.0 and avg >= 0.0:
##    print(name +"'s grade is: \t E")
if avg >= 90.0 and avg <= 100.0:
    print(name +"'s grade is: \t A")
elif avg >= 80.0 and avg <= 89.0:
    print(name +"'s grade is: \t B")
elif avg >= 70.0 and avg <= 79.0:
    print(name +"'s grade is: \t C")
elif avg >= 60.0 and avg <= 69.0:
    print(name +"'s grade is: \t D")
elif avg >= 0.0 and avg <= 59.0:
    print(name +"'s grade is: \t E")

我之所以评论一年级部分是因为我尝试了两种方式都没有运气。

这是我尝试过的，但小数点没有运气

Enter the students name: k
Enter the first score: 89.9
Enter the second score: 89.9
Enter the third score: 89.9
The student's name is: k
k's test scores are:
---------------------------:
TEST1:           89.9
TEST2:           89.9
TEST3:           89.9
k's average is:      89.90000000000002

Answer 1

问题在于您的ifs。当平均值介于 89 和 90、79 和 80 等之间时，你没有理由。此外，除了第一个之外，您不需要任何 ands，因为之前的每次检查都将确认 ands 再次检查的内容。您可以将大部分ifs 缩短为一个条件。

if avg > 100 or avg < 0:
    #check for out of range grades first
    print('Grade out of range')
elif avg >= 90.0:
    print(name +"'s grade is: \t A")
# if the elif is reached, we already know that the grade is below 90, because
# it would have been handled by the previous if, if it were >=90
elif avg >= 80.0:
    print(name +"'s grade is: \t B")
elif avg >= 70.0:  # other wise the previous check will have caught it
    print(name +"'s grade is: \t C")
elif avg >= 60.0:
    print(name +"'s grade is: \t D")
elif avg >= 0.0:
    print(name +"'s grade is: \t E")  # should this be 'F' instead of 'E'?

只是因为我是个好人;）

class Grades:
    def __init__(self, name, *tests):
            self.name = name
            self.tests = list(tests)

    @property
    def avg(self):
        return sum(self.tests)/len(self.tests)

    @property
    def letter_avg(self):
        avg = self.avg
        if avg > 100 or avg < 0:
            raise ValueError('Grade out of range')
        elif avg >= 90.0:
            return 'A'
        elif avg >= 80.0:
            return 'B'
        elif avg >= 70.0:
            return 'B'
        elif avg >= 60.0:
            return 'D'
        elif avg >= 0.0:
            return 'F'

    def __iter__(self):
        return iter(self.tests)

    def __getattr__(self, attr):
        """Allows access such as 'grades.test1' """
        if attr.startswith('test'):
            try:
                num = int(attr[4:])-1
                return self.tests[num]
            except (ValueError, IndexError):
                raise AttributeError('Invalid test number')
        else:
            raise AttributeError(
                'Grades object has no attribute {0}'.format(attr))


def main():
    name = input("Enter the students name: ")
    test1 = float(input("Enter the first score: "))
    test2 = float(input("Enter the second score: "))
    test3 = float(input("Enter the third score: "))
    grades1 = Grades(name, test1, test2, test3)
    print("The student's name is:" , grades1.name)
    print(grades1.name +"'s test scores are:")
    print("---------------------------:")

    for index, test in enumerate(grades1):
        print('TEST{0}: \t\t\t{1}'.format(index, test))

    print("{0}'s average is {1}".format(grades1.name, grades1.avg))
    print("{0}'s average is \t {1}".format(grades1.name, grades1.letter_avg))

if __name__ == '__main__':
    main()

Answer 2

您的if-elif 语句并未涵盖所有可能的值。例如，如果平均值为 89.5，则没有一个块会捕捉到它。解决此问题的最简单方法是从您的 if-elif 语句中删除 <= 子句，因为它们是不必要的。

if avg >= 90.0:
    print(name +"'s grade is: \t A")
elif avg >= 80.0:
    print(name +"'s grade is: \t B")
elif avg >= 70.0:
    print(name +"'s grade is: \t C")
elif avg >= 60.0:
    print(name +"'s grade is: \t D")
else:
    print(name +"'s grade is: \t E")

Answer 3

您遗漏了一些边界情况，例如89.9、79.7，这样的平均值不会在您的程序中打印任何成绩。

你需要这样的东西：

if avg >= 90.0 and avg <= 100.0:
    print(name +"'s grade is: \t A")
elif avg >= 80.0 and avg < 90.0:       #should be <90 not 89.0
    print(name +"'s grade is: \t B")
elif avg >= 70.0 and avg < 80.0:       #should be <80 not 79.0
    print(name +"'s grade is: \t C")
elif avg >= 60.0 and avg < 70.0:       #should be <70 not 69.0
    print(name +"'s grade is: \t D")
elif avg >= 0.0 and avg < 60.0:        #should be <60 not 59.0
    print(name +"'s grade is: \t E")

演示：

The student's name is: dfgd
dfgd's test scores are:
---------------------------:
TEST1:           89.9
TEST2:           89.9
TEST3:           89.9
dfgd's average is:   89.90000000000002
dfgd's grade is:     B

更新：

这里更简洁的解决方案是bisect 模块：

import bisect
lis = [0,60,70,80,90,100]
grades = list('EDCBA')
ind = bisect.bisect_right(lis,avg) -1 
print(name +"'s grade is: \t {}".format(grades[ind]))