为什么我收到此消息无效语法？

Question

i write code if statement but there is a wrong in it. this is the code

mark = float(input('enter your mark : '))
if mark < 50:
    result = 'failed'
elif mark >= 50 and < 75:
    result = 'accepted'
elif mark >= 75 and < 85:
    result = 'good'
elif mark >= 85 and < 90:
    result = 'very good'
else:
    result = 'excellent'
print(result)

the message appear is invalid syntax in line 4 about < assignment any help here guys?

Answer 1

mark >= 50 and < 75 is not a valid expression, you must write mark >= 50 and mark < 75 instead. Alternatively, you can use a chained comparison: 50 <= mark < 75 .

Answer 2

The proper syntax is either elif mark >= 50 and mark < 75: or elif 50 <= mark < 75:

Answer 3

This would be your code that actually runs:

mark = float(input('enter your mark : '))
if mark < 50:
    result = 'failed'
elif mark >= 50 and mark < 75:
    result = 'accepted'
elif mark >= 75 and mark < 85:
    result = 'good'
elif mark >= 85 and mark < 90:
    result = 'very good'
else:
    result = 'excellent'
print(result)

As others stated mark >= 50 and < 85 is not valid in Python.