运算符

介绍

Python 中的运算符是用于对值和变量执行运算的特殊符号和关键字。它们涵盖了从算术和比较到逻辑、按位和赋值运算等各种功能。掌握这些运算符对于构建富有表现力且高效的 Python 代码至关重要，因为它们构成了程序中几乎所有计算或决策过程的基础。下面，您将找到每个运算符的简明示例，以帮助您理解它们的用法和预期结果。

Arithmetic

姓名	象征	操作员	例子
添加	+	a + b	5 + 3 # 8
分配	/	a / b	10 / 4 # 2.5 (always returns a float)
指数运算	**	a ** b	2 ** 3 # 8
楼层划分	//	a // b	10 // 4 # 2 (always returns an integer)
模数	%	a % b	10 % 4 # 2
乘法	*	a * b	5 * 3 # 15
否定	-	- a	- 5 # -5
减法	-	a - b	10 - 3 # 7

Augmented Arithmetic

姓名	象征	操作员	例子
添加	+=	a += b	a = 5 b = 3 a += b # a = 8
分配	/=	a /= b	a = 10 b = 4 a /= b # a = 2.5
指数运算	**=	a **= b	a = 2 b = 3 a **= b # a = 8
楼层划分	//=	a //= b	a = 10 b = 4 a //= b # a = 2
模量	%=	a %= b	a = 10 b = 3 a %= b # a = 1
乘法	*=	a *= b	a = 2 b = 3 a *= b # a = 6
减法	-=	a -= b	a = 10 b = 4 a -= b # a = 6

Comparison

姓名	象征	操作员	例子
平等	==	a == b	5 == 5 # True
不等式	!=	a != b	5 != 10 # True
大于	>{code}	a > b	10 > 5 # True
大于或等于	>=	a >= b	10 >= 5 # True
少于	<	a < b	5 < 10 # True
小于或等于	<=	a <= b	5 <= 5 # True
链式比较	varies	a < b < c	1 < 2 < 3 # True (1 < 2) and (2 < 3)

Logical

姓名	象征	例子
错误的	False	Certain values are defined to be False, including: None False Numeric zero of any type: 0, 0.0, 0j Empty sequences and collections: ‘’ (empty string), [] (empty list), () (empty tuple), {} (empty dictionary), set(), etc.
真的	True	Any object that is not explicitly False is considered True. For instance, non-empty strings, non-zero numbers, non-empty lists, and even custom objects (unless they override the truth value methods to return False) are treated as True.

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姓名	象征	操作员	例子
身份	is	a is b	[1] is [1] # False
非身份	is not	a is not b	5 is not 10 # True
逻辑与	and	a and b	True and False # False
逻辑否定	not	not a	not False # True
逻辑或	or	a or b	False or True # True
条件表达式	if else	x if condition else y	“Yes” if 5 > 3 else “No” # “Yes”

Sequences (Lists, Tuples, Strings)

姓名	象征	操作员	例子
级联	+	seq1 + seq2	[1, 2] + [3, 4] # [1, 2, 3, 4]
切片分配		seq[i:j] = values	lst = [1, 2, 3, 4] lst[1:3] = [20, 30] # lst = [1, 20, 30, 4]
切片删除		del seq[i:j]	lst = [1, 2, 3, 4] del lst[1:3] # lst = [1, 4]
切片		seq[i:j]	lst = [1, 2, 3, 4] lst[1:3] # [2, 3]

Dictionaries (Mappings)

姓名	象征	操作员	例子
索引分配		obj[k] = v	d = {} d[‘a’] = 1 # d = {‘a’: 1}
索引删除		del obj[k]	d = {‘a’: 1} del d[‘a’] # d = {}
索引		obj[k]	d = {‘a’: 1} d[‘a’] # 1

String Formatting

姓名	象征	操作员	例子
字符串格式化	％	s % obj	str = “Hello, %(name)s” % {“name”: “Alice”} # str = ‘Hello, Alice’

Membership

姓名	象征	操作员	例子
遏制测试	in	obj in seq	‘a’ in ‘cat’ # True
成员资格否定（Not In）	not in	a not in b	‘x’ not in ‘hello’ # True

Bitwise

姓名	象征	操作员	例子
按位与	&	a & b	6 & 3 # 2 (0b110 & 0b011 = 0b010)
按位异或（XOR）	^	a ^ b	6 ^ 3 # 5 (0b110 ^ 0b011 = 0b101)
按位反转（NOT）	~	~ a	~5 # -6 (~0b101 yields -6 in two’s complement)
按位或	|	a | b	6 | 3 # 7 (0b110 | 0b011 = 0b111)
左移	<<	a << b	2 << 3 # 16 (0b10 << 3 becomes 0b10000)
右移	>>{code}	a >> b	16 >> 2 # 4 (0b10000 >> 2 becomes 0b100)

Augmented Bitwise

姓名	象征	操作员	例子
增强按位与	&=	a &= b	a = 6 b = 3 a &= b # a = 2 (0b110 & 0b011 = 0b010)
增强按位异或 (XOR)	^=	a ^= b	a = 6 b = 3 a ^= b # a = 5 (0b110 ^ 0b011 = 0b101)
增强按位或	|=	a |= b	a = 6 b = 3 a |= b # a = 7 (0b110 | 0b011 = 0b111)
增强左移	<<=	a <<= b	a = 5 b = 2 a <<= b # a = 20 (5 << 2 equals 5 * 2²)
增强右移	>>=	a >>= b	a = 20 b = 2 a >>= b # a = 5 (20 >> 2 equals 20 // 2²)