python中的语法无效

Question

grade = int(input("Enter Grade: "))

def finalgrade(grade):  

if grade >= 90 and <= 100:
   return "A"

elif grade >=80 and <= 89:
    return "B"
else:
    return "F"

抱怨invalid syntax in = sign before 100

任何帮助都将不胜感激

Answer 1

elif grade >=80 and <= 89:是错误的；应该有一些东西与89相比较。我猜你的意思是elif grade >=80 and grade <= 89:。90-100部分也是如此。你知道吗

Answer 2

elif grade >=80 and <= 89:应该是elif grade >=80 and grade <= 89:，if grade >= 90 and <= 100:应该是if grade >= 90 and grade <= 100:

Answer 3

问题是你没有明确地将100或89与任何事物进行比较。这是更好的语法：

if 90 <= grade <= 100:
    return "A"
elif 80 <= grade <= 89:
    return "B"
else:
    return "F"

但更接近于您的编写方式，您需要在两个比较中都包含grade：

if grade >= 90 and grade <= 100:
     return "A"
elif grade >=80 and grade <= 89:
    return "B"
else:
    return "F"

另外，您可能需要考虑grade=89.5的可能性，并将范围更改为80 <= grade < 90，使用<而不是<=