Python Full Stack Road Series: Assignment and Operators

Before continuing with the following article, let's first take a look at several operators provided by Python for us. Define two variables, a and b. The value of a is 10 and the value of b is 20.

Arithmetic Operator

##*Multiple, the two numbers are equivalent or Returns a string repeated several timesa*b=200/Divide two objectsb/a=2%Take the membrane and return the remainder of the divisionb%a=0**Power, returns the y power of xa**b=100000000000000000000L//Remainder of integer division, return the integer part of the quotienta//b=0##Comparison operator

Operator	Description	Example
+	Add, add two objects	a+b=30
-	Subtract, subtract two objects, you may get a negative number	a-b=-10

Operator##====Equals , compare whether two objects are equala==bReturn False!=Not equal, compare whether two objects are not equala!=b returns TrueNot equal, compare whether two objects are equal is greater than, compares whether x is greater than y, Less than, compare whether x is less than y##>=Greater than or equal to, compare whether x is greater than or equal to ya>=b returns FalseLess than or equal to, compare Whether x is less than or equal to ya

Description	Instance
		##
a< ;>b returns True		>
a>b returns False
a
	Assignment operator

## Operator

DescriptionInstanceAssignment Operator c=a+b, assign the operation result of a+b to c##+=addition copy operatorc += a, etc. Effective for c = c + a-=Subtractive copy operatorc -= a is equivalent to c = c - a*=Multiplicative copy operatorc = a is equivalent to c = c a/=c /= a is equivalent to c = c / a%=Modulo assignment operatorc %= a is equivalent to c = c % a**=Power assignment operator c = a is equivalent to c = c a//=c //= a is equivalent to c = c // aOperation Symbol

		=
		Division copy operator
		Integer division assignment operator
	Logical operator

Description

Instanceand"with"a and b returns trueor"or"a or b returns truenot "Not"no(a and b) returns false##Member operatorOperatorDescription

not in

赋值语句的语法

in	Returns True if the value is found in the specified sequence , otherwise it returns False
If the value is not found in the specified sequence, it returns True, otherwise it returns false

运算	解释
spam='Spam'	基本形式
spam, ham='yum', 'YUM'	元组赋值运算
[spam, han]=['yum', 'YUM']	列表赋值运算
a,b,c,d='spam'	序列赋值运算，通用性
a, *b='spam'	扩展的序列解包
spam = ham = 'hello'	多目标赋值运算
spams += 42	增强赋值运算

实例

序列运算

>>> nudge = 1
>>> wink = 2
>>> A, B = nudge, wink
>>> A,B
(1, 2)
# 嵌套的方式
>>> ((a, b), c) = ('SP', 'AM')
>>> a, b, c
('S', 'P', 'AM')

扩展的序列解包

一个列表赋给了带星号的名称，该列表收集了序列中没有赋值给其他名称的所有项。

先定义一个seq序列用于测试:

>>> seq = [1, 2, 3, 4]

a匹配序列中的第一项，b匹配剩下的内容

>>> a, *b = seq
>>> a, b
(1, [2, 3, 4])

b匹配序列中的最后一项，a匹配序列中最后一项之前的所有内容

>>> *a, b = seq
>>> a,b
([1, 2, 3], 4)

第一项个最后一项分别赋值给了a和c，而b获取了二者之间的所有内容。

>>> *a, b, c = seq
>>> a,b,c
([1, 2], 3, 4)

带星号的名称可能只匹配单个的项，但是，总会向其复制一个列表，如果没有剩下的内容可以匹配那么会返回一个空列表：

>>> a,b,c,*d = seq
>>> print(a,b,c,d)
1 2 3 [4]
>>> a,b,c,d,*e = seq
>>> print(a,b,c,d,e)
1 2 3 4 []

多目标赋值语句就是直接把所有提供的变量名都赋值给右侧的对象

>>> a = b = c = 'As'
>>> a,b,c
('As', 'As', 'As')
# 所引用的值也都是同一个
>>> id(a),id(b),id(c)
(4331109208, 4331109208, 4331109208)

                                               

Before continuing with the following article, let's first take a look at several operators provided by Python for us. Define two variables, a and b. The value of a is 10 and the value of b is 20.

Arithmetic Operator

##*Multiple, the two numbers are equivalent or Returns a string repeated several timesa*b=200/Divide two objectsb/a=2%Take the membrane and return the remainder of the divisionb%a=0**Power, returns the y power of xa**b=100000000000000000000L//Remainder of integer division, return the integer part of the quotienta//b=0##Comparison operator

Operator	Description	Example
+	Add, add two objects	a+b=30
-	Subtract, subtract two objects, you may get a negative number	a-b=-10

Operator##====Equals , compare whether two objects are equala==bReturn False!=Not equal, compare whether two objects are not equala!=b returns TrueNot equal, compare whether two objects are equal is greater than, compares whether x is greater than y, Less than, compare whether x is less than y##>=Greater than or equal to, compare whether x is greater than or equal to ya>=b returns FalseLess than or equal to, compare Whether x is less than or equal to ya

Description	Instance
		##
a< ;>b returns True		>
a>b returns False
a
	Assignment operator

## Operator

DescriptionInstanceAssignment Operator c=a+b, assign the operation result of a+b to c##+=addition copy operatorc += a, etc. Effective for c = c + a-=Subtractive copy operatorc -= a is equivalent to c = c - a*=Multiplicative copy operatorc = a is equivalent to c = c a/=c /= a is equivalent to c = c / a%=Modulo assignment operatorc %= a is equivalent to c = c % a**=Power assignment operator c = a is equivalent to c = c a//=c //= a is equivalent to c = c // aOperation Symbol

		=
		Division copy operator
		Integer division assignment operator
	Logical operator

Description

Instanceand"with"a and b returns trueor"or"a or b returns truenot "Not"no(a and b) returns false##Member operatorOperatorDescription

not in

赋值语句的语法

in	Returns True if the value is found in the specified sequence , otherwise it returns False
If the value is not found in the specified sequence, it returns True, otherwise it returns false

运算	解释
spam='Spam'	基本形式
spam, ham='yum', 'YUM'	元组赋值运算
[spam, han]=['yum', 'YUM']	列表赋值运算
a,b,c,d='spam'	序列赋值运算，通用性
a, *b='spam'	扩展的序列解包
spam = ham = 'hello'	多目标赋值运算
spams += 42	增强赋值运算

实例

序列运算

>>> nudge = 1
>>> wink = 2
>>> A, B = nudge, wink
>>> A,B
(1, 2)
# 嵌套的方式
>>> ((a, b), c) = ('SP', 'AM')
>>> a, b, c
('S', 'P', 'AM')

扩展的序列解包

一个列表赋给了带星号的名称，该列表收集了序列中没有赋值给其他名称的所有项。

先定义一个seq序列用于测试:

>>> seq = [1, 2, 3, 4]

a匹配序列中的第一项，b匹配剩下的内容

>>> a, *b = seq
>>> a, b
(1, [2, 3, 4])

b匹配序列中的最后一项，a匹配序列中最后一项之前的所有内容

>>> *a, b = seq
>>> a,b
([1, 2, 3], 4)

第一项个最后一项分别赋值给了a和c，而b获取了二者之间的所有内容。

>>> *a, b, c = seq
>>> a,b,c
([1, 2], 3, 4)

带星号的名称可能只匹配单个的项，但是，总会向其复制一个列表，如果没有剩下的内容可以匹配那么会返回一个空列表：

>>> a,b,c,*d = seq
>>> print(a,b,c,d)
1 2 3 [4]
>>> a,b,c,d,*e = seq
>>> print(a,b,c,d,e)
1 2 3 4 []

多目标赋值语句就是直接把所有提供的变量名都赋值给右侧的对象

>>> a = b = c = 'As'
>>> a,b,c
('As', 'As', 'As')
# 所引用的值也都是同一个
>>> id(a),id(b),id(c)
(4331109208, 4331109208, 4331109208)

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