Question

我正在制作更改计数器，而且我在打印等级的百分比时遇到问题，每当我运行程序时，我可以输入尽可能多的输入，但是，当我输入完成时，应该终止程序并给用户留下百分比和字母等级，它只是结束程序。如果我能得到任何建议，我将不胜感激。这是我的代码：

grade=""
total=0
count=1
scores=''

while scores != 'done':
    scores=input("Enter Homework score: ")
    if scores.isdigit():
        numeric=int(scores)
        percentage=(numeric*10/count)
    elif percentage >= 92 and percentage < 100:
        letter = 'A'
    elif percentage >= 87 and percentage < 92:
        letter = 'B+'
    elif percentage >= 80 and percentage < 87:
        letter = 'B'
    elif percentage >=77 and percentage < 80:
        letter = 'C+'
    elif percentage >=70 and percentage < 77:
        letter = 'C'
    elif percentage >= 67 and percentage < 70:
        letter = 'D+'
    elif percentage >= 60 and percentage < 67:
        letter = 'D'
    elif percentage < 60 and percentage >= 0:
        letter= 'F'
    elif (numeric) < 0:
        print("Score must be between 0 and 10")
    elif (numeric) > 10:
        print("Score must be between 0 and 10")
    elif (scores)== 'done':
         print(percentage,"% and you got an, ",letter)

Answer 1

您的条件逻辑存在缺陷。如果letter：

，您永远不会评估成绩（score.isdigit()）

while scores != 'done':
    scores=input("Enter Homework score: ")
    if scores.isdigit():
        numeric=int(scores)
        percentage=(numeric*10/count)
        if percentage >= 92 and percentage < 100:
            letter = 'A'
        elif percentage >= 87 and percentage < 92:
            letter = 'B+'
        ...

如果初始条件为假，则跳出循环通常更清晰，例如：

while scores != 'done':
    scores=input("Enter Homework score: ")
    if not scores.isdigit():
        continue

    numeric=int(scores)
    percentage=(numeric*10/count)
    if 92 <= percentage < 100:
        letter = 'A'
    elif 87 <= percentage < 92:
        letter = 'B+'
    ...

同样在python中，你不应该害怕例外。 python中常见的习语是EAFP（比宽容更容易要求宽恕）：

while scores != 'done':
    scores=input("Enter Homework score: ")
    try:
        numeric = int(scores)
    except ValueError:
        continue

您可能还想考虑更好的方法来执行大成绩if elif elif ...阻止。例如。另一种方法是定义成绩词典：

grades = {'A': (92, 100), 'B+': (87, 92)} # Etc..
score = 93
_, letter = max((low <= score < high, letter) for letter, (low, high) in grades.items())
print(letter) # 'A'

Answer 2

您的代码应类似于下面的代码。虽然我仍然无法评估你的程序背后的逻辑（因为你没有在你的问题中解释，例如percentage=(numeric*10/count)对我来说似乎不太正确，等等），但下面的代码解决了你当前的问题（基于你当前的问题）。

grade=""
total=0
count=1
scores=''

percentage = 0

while scores != 'done':
    scores=input("Enter Homework score: ")

    if scores.isdigit():
        numeric=int(scores)

        if numeric < 0:
            print("Score must be between 0 and 10")
        elif numeric > 10:
            print("Score must be between 0 and 10")

        percentage=(numeric*10/count)



if percentage >= 92 and percentage < 100: # I would change this to if percentage >= 92 and percentage <= 100:
    letter = 'A'
elif percentage >= 87 and percentage < 92:
    letter = 'B+'
elif percentage >= 80 and percentage < 87:
    letter = 'B'
elif percentage >=77 and percentage < 80:
    letter = 'C+'
elif percentage >=70 and percentage < 77:
    letter = 'C'
elif percentage >= 67 and percentage < 70:
    letter = 'D+'
elif percentage >= 60 and percentage < 67:
    letter = 'D'
elif percentage < 60 and percentage >= 0:  #I would change this to else:
    letter= 'F'

print(percentage,"% and you got an, ",letter)

变量计数程序的if语句中未定义的变量

2 个答案: