Python - 用户输入数据类型

Question

我用 Python 3.x 编写了以下代码来验证用户的输入:

while True:
    try:
        answer = int(input("Enter an integer: "))
    except ValueError:
        print("That's not a whole number. Try again.")

我知道输入“hi”或“hi46”将是字符串(并且会导致 ValueError)。

输入“”(无)会是什么数据类型？输入“]%$”(符号)怎么样？

Answer 1

假设您使用的是 python 3.X，用户输入的所有内容都将是一个字符串。甚至是看起来像“23”或“0”的数字。 int(thing) 不验证 thing 是否为整数类型。它尝试将 thing 从现在的任何类型转换为整数类型，如果不可能，则会引发 ValueError。

演示:

>>> while True:
...     x = input("Enter something: ")
...     print("You entered {}".format(x))
...     print("That object's type is: {}".format(type(x)))
...
Enter something: hi
You entered hi
That object's type is: <class 'str'>
Enter something: hi46
You entered hi46
That object's type is: <class 'str'>
Enter something: 
You entered
That object's type is: <class 'str'>
Enter something: ]%$
You entered ]%$
That object's type is: <class 'str'>
Enter something: 23
You entered 23
That object's type is: <class 'str'>
Enter something: 42
You entered 42
That object's type is: <class 'str'>
Enter something: 0
You entered 0
That object's type is: <class 'str'>