功能不断要求输入

Question

我编写的函数绘制了 square、triangle 或 rectangle。它要求用户输入他们想要绘制的形状。如果输入不是以下之一，它会重新要求用户输入有效的输入：

有效输入

square,
triangle,
rectangle,
q #function Quits.

我遇到的问题是，当用户第一次键入有效输入时，该函数会完美运行并绘制该形状。但是，如果用户首先输入 "invalid input"，例如（圆圈），它会要求用户重新输入 "valid input(shape)"。当他这样做时，无穷大函数一直在说：

错误信息

Unknown shape. Please try again
Enter shape to draw (q to quit):

代码

def get_valid_shape():
''' Asking the user to enter a valid shape that the function can draw '''
    shape = input("Enter shape to draw (q to quit): ").lower()
    unvalid_names1 = shape != "triangle" and shape != "square"
    unvalid_names2 = shape != "rectangle" and shape != "q"

    while unvalid_names1 == True and unvalid_names2 == True:
        print("Unknown shape. Please try again")
        shape = input("Enter shape to draw (q to quit): ").lower()
    if shape == "q":
        print("Goodbye")
    return

有人能帮忙吗？

Answer 1

这是因为您在没有条件跳出循环的情况下要求循环内的下一个值。一个简单的修复方法是：

def get_valid_shape():
    ''' Asking the user to enter a valid shape that the function can draw '''
    shape = input("Enter shape to draw (q to quit): ").lower()
    unvalid_names1 = shape != "triangle" and shape != "square"
    unvalid_names2 = shape != "rectangle" and shape != "q"
    quit = False

    while not quit and unvalid_names1 == True and unvalid_names2 == True:
        print("Unknown shape. Please try again")
        shape = input("Enter shape to draw (q to quit): ").lower()
        quit = shape == 'q'

    if shape == "q":
        print("Goodbye")
    return

get_valid_shape()

除此之外，您的代码很难理解。我冒昧地制作了另一个版本。可读性确实是意见，但它也解决了您的问题，同时使（恕我直言）更清楚您要做什么：

def get_valid_shape():
    ''' Asking the user to enter a valid shape that the function can draw '''
    valid_shapes = set(['triangle', 'square', 'rectangle'])
    user_quit = False
    requested_shape = ''

    while True:
        requested_shape = input("Enter shape to draw (q to quit): ").lower()
        if requested_shape in valid_shapes:
            break
        elif requested_shape == 'q':
            user_quit = True
            break
        else:
            print('Invalid shape')

    if not user_quit:
        print('Would now print shape')
    else:
        print('Goodbye')

get_valid_shape()

功能不断要求输入

function keeps asking for input

python-3.x

infinite-loop