python-3.x - 仅接受介于0和1之间的 float -python

Question

因此，我需要一个真正有效的代码，该代码将接受用户的0到1之间的任何数字，并不断提示他们重试，直到他们的输入满足此条件。
到目前为止，这是我得到的:

def user_input():
while True:
    global initial_input
    initial_input = input("Please enter a number between 1 and 0")
    if initial_input.isnumeric() and (0 <= float(initial_input) <= 1):
        initial_input = float(initial_input)
        return(initial_input)
    print("Please try again, it must be a number between 0 and 1")
user_input()

这有效，但仅当数字实际为1或0时。如果您在两者之间输入小数(例如0.6)，则会崩溃

Answer 1

仅当输入是介于0和1之间的数字时，才应使用try/except返回输入，将错误的输入捕获为ValueError:

def user_input():
    while True:
        try:
            # cast to float
            initial_input = float(input("Please enter a number between 1 and 0"))      # check it is in the correct range and is so return 
            if 0 <= initial_input <= 1:
                return (initial_input)
            # else tell user they are not in the correct range
            print("Please try again, it must be a number between 0 and 1")
        except ValueError:
            # got something that could not be cast to a float
            print("Input must be numeric.")

另外，如果您使用自己的代码获取"Unresolved attribute reference 'is numeric' for class 'float'".，则说明您使用的是python2而不是python3，因为您只在等数字检查后才进行转换，因此意味着输入已被评估。如果是这种情况，请使用raw_input代替输入。