Question

我正在寻求以下3个while循环的帮助：

while choice is None:  ...
while not isinstance (choice, int):  ...
while int(choice) not in range(0,1):  ...

可能是这样的：

while choice is None and not isinstance (choice, int) and int(choice) not in range(0,1):
    print("Invalid option!")
    choice = input("Choose key: ")

我该如何正确嵌套呢？

choice = None
choice = input("Choose key: ")

while choice is None:
    choice = input("Choose key: ")

while not isinstance (choice, int):
    print("choice is an integer and I equal 0 or 1")
    print("Also if I am None or not an int, I will loop until I meet I am")

while int(choice) not in range(0,1):
    choice = input("Choose key: ")
    choice = int(choice)

Answer 1

您可以通过将所有内容移入一个循环来很好地压缩它：

while True:
    choice = input("Choose key: ")
    if choice in ("0", "1"):
        choice = int(choice)
        break

Answer 2

input返回一个str对象，即句点。它永远不会返回None，也永远不会返回int。只需（尝试）将choice转换为int，然后检查结果值，只有在输入0或1时才中断。

while True:
    choice = input("Choose key: ")
    try:
        choice = int(choice)
    except ValueError:
        continue
    if choice in (0, 1):
        break

Answer 3

如果您需要整数输入...

while True:
    try:
        choice = int(input('Enter choice: '))
    except ValueError:
        print('Invalid choice')
    else:
        # add an if statement here to add another condition to test the int against before accepting input
        break
# .... do whatever next with you integer

Answer 4

如果我了解得很清楚，这与嵌套无关，而与订购有关，对吗？怎么样：

In [10]: choice = None

In [11]: while (
...:     not choice or
...:     not choice.isdigit() or
...:     int(choice) not in range(0,2)
...: ):
...:     print("Invalid option!")
...:     choice = input("Choose key: ")

Answer 5

choice = None
while choice not in range(0,1):
    choice = int(input("Choose key: "))

我不知道那是你想做的

while循环正确的嵌套

5 个答案: