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EX.What's wrong with booleans

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暮晨 2018-11-17 13:08:03 +08:00 committed by 暮晨
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@ -40,7 +40,7 @@ So, here we go...
- [> not knot!/别纠结!](#-not-knot别纠结) - [> not knot!/别纠结!](#-not-knot别纠结)
- [> Half triple-quoted strings/三个引号](#-half-triple-quoted-strings三个引号) - [> Half triple-quoted strings/三个引号](#-half-triple-quoted-strings三个引号)
- [> Midnight time doesn't exist?/不存在的午夜?](#-midnight-time-doesnt-exist不存在的午夜) - [> Midnight time doesn't exist?/不存在的午夜?](#-midnight-time-doesnt-exist不存在的午夜)
- [> What's wrong with booleans?](#-whats-wrong-with-booleans) - [> What's wrong with booleans?/布尔你咋了?](#-whats-wrong-with-booleans布尔你咋了)
- [> Class attributes and instance attributes](#-class-attributes-and-instance-attributes) - [> Class attributes and instance attributes](#-class-attributes-and-instance-attributes)
- [> yielding None](#-yielding-none) - [> yielding None](#-yielding-none)
- [> Mutating the immutable!](#-mutating-the-immutable) - [> Mutating the immutable!](#-mutating-the-immutable)
@ -763,12 +763,11 @@ midnight_time 并没有被输出.
--- ---
### > What's wrong with booleans? ### > What's wrong with booleans?/布尔你咋了?
1\. 1\.
```py ```py
# A simple example to count the number of boolean and # 一个简单的例子, 统计下面可迭代对象中的布尔型值的个数和整型值的个数
# integers in an iterable of mixed data types.
mixed_list = [False, 1.0, "some_string", 3, True, [], False] mixed_list = [False, 1.0, "some_string", 3, True, [], False]
integers_found_so_far = 0 integers_found_so_far = 0
booleans_found_so_far = 0 booleans_found_so_far = 0
@ -812,9 +811,9 @@ another_dict[1.0] = "Python"
'' ''
``` ```
#### 💡 Explanation: #### 💡 说明:
* Booleans are a subclass of `int` * 布尔值是 `int` 的子类
```py ```py
>>> isinstance(True, int) >>> isinstance(True, int)
True True
@ -822,13 +821,13 @@ another_dict[1.0] = "Python"
True True
``` ```
* The integer value of `True` is `1` and that of `False` is `0`. * 所以 `True` 的整数值是 `1`, 而 `False` 的整数值是 `0`.
```py ```py
>>> True == 1 == 1.0 and False == 0 == 0.0 >>> True == 1 == 1.0 and False == 0 == 0.0
True True
``` ```
* See this StackOverflow [answer](https://stackoverflow.com/a/8169049/4354153) for the rationale behind it. * 关于其背后的原理, 请看这个 StackOverflow 的[回答](https://stackoverflow.com/a/8169049/4354153).
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