mirror of https://github.com/TwoWater/Python
113 lines
3.4 KiB
Markdown
113 lines
3.4 KiB
Markdown
# 六、运算符相关的魔术方法 #
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运算符相关的魔术方法实在太多了,j就大概列举下面两类：
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## 1、比较运算符 ##
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|魔术方法|说明|
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|-----|-----|
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|`__cmp__(self, other)`|如果该方法返回负数，说明 `self < other`; 返回正数，说明 `self > other`; 返回 0 说明 `self == other `。强烈不推荐来定义 `__cmp__` , 取而代之, 最好分别定义 `__lt__`, `__eq__` 等方法从而实现比较功能。 `__cmp__` 在 Python3 中被废弃了。|
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|`__eq__(self, other)`|定义了比较操作符 == 的行为|
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|`__ne__(self, other)`|定义了比较操作符 != 的行为|
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|`__lt__(self, other)`|定义了比较操作符 < 的行为|
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|`__gt__(self, other)`|定义了比较操作符 > 的行为|
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|`__le__(self, other)`|定义了比较操作符 <= 的行为|
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|`__ge__(self, other)`|定义了比较操作符 >= 的行为|
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来看个简单的例子就能理解了：
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```python
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#!/usr/bin/env python3
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# -*- coding: UTF-8 -*-
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class Number(object):
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def __init__(self, value):
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self.value = value
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def __eq__(self, other):
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print('__eq__')
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return self.value == other.value
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def __ne__(self, other):
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print('__ne__')
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return self.value != other.value
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def __lt__(self, other):
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print('__lt__')
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return self.value < other.value
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def __gt__(self, other):
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print('__gt__')
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return self.value > other.value
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def __le__(self, other):
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print('__le__')
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return self.value <= other.value
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def __ge__(self, other):
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print('__ge__')
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return self.value >= other.value
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if __name__ == '__main__':
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num1 = Number(2)
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num2 = Number(3)
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print('num1 == num2 ? --------> {} \n'.format(num1 == num2))
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print('num1 != num2 ? --------> {} \n'.format(num1 == num2))
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print('num1 < num2 ? --------> {} \n'.format(num1 < num2))
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print('num1 > num2 ? --------> {} \n'.format(num1 > num2))
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print('num1 <= num2 ? --------> {} \n'.format(num1 <= num2))
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print('num1 >= num2 ? --------> {} \n'.format(num1 >= num2))
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```
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输出的结果为：
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```txt
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__eq__
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num1 == num2 ? --------> False
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__eq__
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num1 != num2 ? --------> False
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__lt__
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num1 < num2 ? --------> True
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__gt__
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num1 > num2 ? --------> False
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__le__
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num1 <= num2 ? --------> True
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__ge__
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num1 >= num2 ? --------> False
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```
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## 2、算术运算符 ##
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|魔术方法|说明|
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|-----|-----|
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|`__add__(self, other)`|实现了加号运算|
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|`__sub__(self, other)`|实现了减号运算|
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|`__mul__(self, other)`|实现了乘法运算|
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|`__floordiv__(self, other)`|实现了 // 运算符|
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|`___div__(self, other)`|实现了/运算符. 该方法在 Python3 中废弃. 原因是 Python3 中，division 默认就是 true division|
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|`__truediv__(self, other)`|实现了 true division. 只有你声明了 `from __future__ import division` 该方法才会生效|
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|`__mod__(self, other)`|实现了 % 运算符, 取余运算|
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|`__divmod__(self, other)`|实现了 divmod() 內建函数|
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|`__pow__(self, other)`|实现了 `**` 操作. N 次方操作|
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|`__lshift__(self, other)`|实现了位操作 `<<`|
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|`__rshift__(self, other)`|实现了位操作 `>>`|
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|`__and__(self, other)`|实现了位操作 `&`|
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|`__or__(self, other)`|实现了位操作 `|`|
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|`__xor__(self, other)`|实现了位操作 `^`|
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最后，如果对本文感兴趣的，可以关注下公众号：
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