“字符串"的逻辑值是什么?在 Python 中? [英] What's the logical value of "string" in Python?

问题描述

我错误地用 Python 编写了这段代码:

I erroneously wrote this code in Python:

name = input("what is your name?")
if name == "Kamran" or "Samaneh":
    print("That is a nice name")
else:
    print("You have a boring name ;)")

即使输入既不是Kamran"也不是Samaneh"，它总是会打印出那是个好名字".

It always prints out "That is a nice name" even when the input is neither "Kamran" nor "Samaneh".

我说它认为Samaneh"是真的是对的吗?为什么?

Am I correct in saying that it considers "Samaneh" as a true? Why?

顺便说一下，我已经注意到我的错误了.正确的形式是:

By the way, I already noticed my mistake. The correct form is:

if name == "Kamran" or name == "Samaneh":

推荐答案

Python(和大多数其他语言)中的任何非空字符串都是真的，所有非零数字和非空列表、字典、集合和元组也是如此.¹

Any non empty string in Python (and most other languages) is true as are all non-zero numbers and non-empty lists, dictionaries, sets and tuples.¹

做你想做的更好的方法是:

A nicer way to do what you want is:

name = input("what is your name?")
if name in ("Kamran", "Samaneh"):
    print("That is a nice name")
else:
    print("You have a boring name ;)")

这将创建一个包含您想要的名称的元组并执行成员资格测试.

This creates a tuple containing the names that you want and performs a membership test.

^{1 正如 delnan 在评论中指出的，这适用于所有写得好的集合.也就是说，如果你实现了自定义的集合类，请确保它为空时为false.}

^{1 As delnan points out in the comments, this applies to all well written collections. That is, if you implement a custom collection class, make sure that it is false when it's empty.}

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