python 运算符实例教程详解

发布时间:2020-09-09编辑:脚本学堂
有关python运算符的实例教程,内容非常全面,包括了python算术运算符、python比较运算符、python赋值运算符、python位运算符、python运算符的优先级等常用知识,需要的朋友参考下。

python运算符

例子 4 +5 = 9 ,4和5被称为操作数,"+"号为运算符。 
 
Python语言支持以下类型的运算符: 
算术运算符 
比较(关系)运算符 
赋值运算符 
逻辑运算符 
位运算符 
成员运算符 
身份运算符 
运算符优先级 

学习Python的运算符。  
 
1、Python算术运算符 
以下假设变量a为10,变量b为20: 
 
运算符 描述  实例 
+   加 - 两个对象相加   a + b 输出结果 30 
-   减 - 得到负数或是一个数减去另一个数  a - b 输出结果 -10 
*   乘 - 两个数相乘或是返回一个被重复若干次的字符串    a * b 输出结果 200 
/   除 - x除以y     b / a 输出结果 2 
%   取模 - 返回除法的余数     b % a 输出结果 0 
**  幂 - 返回x的y次幂  a**b 为10的20次方, 输出结果 100000000000000000000 
//  取整除 - 返回商的整数部分   9//2 输出结果 4 , 9.0//2.0 输出结果 4.0 

例子,Python所有算术运算符的操作: 
 

复制代码 代码示例:
#!/usr/bin/python
a = 21 
b = 10 
c = 0 
 
c = a + b 
print "Line 1 - Value of c is ", c 
 
c = a - b 
print "Line 2 - Value of c is ", c  
 
c = a * b 
print "Line 3 - Value of c is ", c  
 
c = a / b 
print "Line 4 - Value of c is ", c  
 
c = a % b 
print "Line 5 - Value of c is ", c 
 
a = 2 
b = 3 
c = a**b  
print "Line 6 - Value of c is ", c 
 
a = 10 
b = 5 
c = a//b  
print "Line 7 - Value of c is ", c 

输出结果: 
Line 1 - Value of c is 31 
Line 2 - Value of c is 11 
Line 3 - Value of c is 210 
Line 4 - Value of c is 2 
Line 5 - Value of c is 1 
Line 6 - Value of c is 8 
Line 7 - Value of c is 2 

2、Python比较运算符 
以下假设变量a为10,变量b为20: 
运算符 描述  实例 
 

==   等于 - 比较对象是否相等   (a == b) 返回 False。 
!=   不等于 - 比较两个对象是否不相等   (a != b) 返回 true. 
<>    不等于 - 比较两个对象是否不相等    (a <> b) 返回 true。这个运算符类似 != 。 
>     大于 - 返回x是否大于y   (a > b) 返回 False。 
<     小于 - 返回x是否小于y。所有比较运算符返回1表示真,返回0表示假。这分别与特殊的变量True和False等价。注意,这些变量名的大写。   (a < b) 返回 true。 
>=    大于等于 - 返回x是否大于等于y。  (a >= b) 返回 False。 
<=    小于等于 - 返回x是否小于等于y。  (a <= b) 返回 true。 

Python所有比较运算符的操作: 
 

复制代码 代码示例:
#!/usr/bin/python 
a = 21 
b = 10 
c = 0 
 
if ( a == b ): 
   print "Line 1 - a is equal to b" 
else: 
   print "Line 1 - a is not equal to b" 
 
if ( a != b ): 
   print "Line 2 - a is not equal to b" 
else: 
   print "Line 2 - a is equal to b" 
 
if ( a <> b ): 
   print "Line 3 - a is not equal to b" 
else: 
   print "Line 3 - a is equal to b" 
 
if ( a < b ): 
   print "Line 4 - a is less than b"  
else: 
   print "Line 4 - a is not less than b" 
 
if ( a > b ): 
   print "Line 5 - a is greater than b" 
else: 
   print "Line 5 - a is not greater than b" 
 
a = 5; 
b = 20; 
if ( a <= b ): 
   print "Line 6 - a is either less than or equal to  b" 
else: 
   print "Line 6 - a is neither less than nor equal to  b" 
 
if ( b >= a ): 
   print "Line 7 - b is either greater than  or equal to b" 
else: 
   print "Line 7 - b is neither greater than  nor equal to b" 

输出结果: 
Line 1 - a is not equal to b 
Line 2 - a is not equal to b 
Line 3 - a is not equal to b 
Line 4 - a is not less than b 
Line 5 - a is greater than b 
Line 6 - a is either less than or equal to b 
Line 7 - b is either greater than or equal to b  

3、Python赋值运算符 
以下假设变量a为10,变量b为20: 
运算符 描述  实例 
 

=   简单的赋值运算符     c = a + b 将 a + b 的运算结果赋值为 c 
+=  加法赋值运算符  c += a 等效于 c = c + a 
-=  减法赋值运算符  c -= a 等效于 c = c - a 
*=  乘法赋值运算符  c *= a 等效于 c = c * a 
/=  除法赋值运算符  c /= a 等效于 c = c / a 
%=  取模赋值运算符  c %= a 等效于 c = c % a 
**= 幂赋值运算符   c **= a 等效于 c = c ** a 
//=  取整除赋值运算符    c //= a 等效于 c = c // a 

Python所有赋值运算符的操作: 
 

复制代码 代码示例:
#!/usr/bin/python 
 
a = 21 
b = 10 
c = 0 
 
c = a + b 
print "Line 1 - Value of c is ", c 
 
c += a 
print "Line 2 - Value of c is ", c  
 
c *= a 
print "Line 3 - Value of c is ", c  
 
c /= a  
print "Line 4 - Value of c is ", c  
 
c  = 2 
c %= a 
print "Line 5 - Value of c is ", c 
 
c **= a 
print "Line 6 - Value of c is ", c 
 
c //= a 
print "Line 7 - Value of c is ", c 

输出结果: 
Line 1 - Value of c is 31 
Line 2 - Value of c is 52 
Line 3 - Value of c is 1092 
Line 4 - Value of c is 52 
Line 5 - Value of c is 2 
Line 6 - Value of c is 2097152 
Line 7 - Value of c is 99864 

4、Python位运算符 
按位运算符是把数字看作二进制来进行计算的。Python中的按位运算法则如下: 
运算符 描述  实例 
 

&    按位与运算符  (a & b) 输出结果 12 ,二进制解释: 0000 1100 
|    按位或运算符  (a | b) 输出结果 61 ,二进制解释: 0011 1101 
^    按位异或运算符     (a ^ b) 输出结果 49 ,二进制解释: 0011 0001 
~    按位取反运算符     (~a ) 输出结果 -61 ,二进制解释: 1100 0011, 在一个有符号二进制数的补码形式。 
<<    左移动运算符   a << 2 输出结果 240 ,二进制解释: 1111 0000 
>>     右移动运算符  a >> 2 输出结果 15 ,二进制解释: 0000 1111 

Python所有位运算符的操作: 
 

复制代码 代码示例:
#!/usr/bin/python 
 
a = 60            # 60 = 0011 1100  
b = 13            # 13 = 0000 1101  
c = 0 
 
c = a & b;        # 12 = 0000 1100 
print "Line 1 - Value of c is ", c 
 
c = a | b;        # 61 = 0011 1101  
print "Line 2 - Value of c is ", c 
 
c = a ^ b;        # 49 = 0011 0001 
print "Line 3 - Value of c is ", c 
 
c = ~a;           # -61 = 1100 0011 
print "Line 4 - Value of c is ", c 
 
c = a << 2;       # 240 = 1111 0000 
print "Line 5 - Value of c is ", c 
 
c = a >> 2;       # 15 = 0000 1111 
print "Line 6 - Value of c is ", c 

输出结果: 
Line 1 - Value of c is 12 
Line 2 - Value of c is 61 
Line 3 - Value of c is 49 
Line 4 - Value of c is -61 
Line 5 - Value of c is 240 
Line 6 - Value of c is 15 

5、Python逻辑运算符 
Python语言支持逻辑运算符,以下假设变量a为10,变量b为20: 
运算符 描述  实例 
 

and  布尔"与" - 如果x为False,x and y返回False,否则它返回y的计算值。    (a and b) 返回 true。 
or  布尔"或" - 如果x是True,它返回True,否则它返回y的计算值。     (a or b) 返回 true。 
not 布尔"非" - 如果x为True,返回False。如果x为False,它返回True。  not(a and b) 返回 false。 

Python所有逻辑运算符的操作: 
 

复制代码 代码示例:
#!/usr/bin/python 
 
a = 10 
b = 20 
c = 0 
 
if ( a and b ): 
   print "Line 1 - a and b are true" 
else: 
   print "Line 1 - Either a is not true or b is not true" 
 
if ( a or b ): 
   print "Line 2 - Either a is true or b is true or both are true" 
else: 
   print "Line 2 - Neither a is true nor b is true" 
 
 
a = 0 
if ( a and b ): 
   print "Line 3 - a and b are true" 
else: 
   print "Line 3 - Either a is not true or b is not true" 
 
if ( a or b ): 
   print "Line 4 - Either a is true or b is true or both are true" 
else: 
   print "Line 4 - Neither a is true nor b is true" 
 
if not( a and b ): 
   print "Line 5 - a and b are true" 
else: 
   print "Line 5 - Either a is not true or b is not true" 

输出结果: 
Line 1 - a and b are true 
Line 2 - Either a is true or b is true or both are true 
Line 3 - Either a is not true or b is not true 
Line 4 - Either a is true or b is true or both are true 
Line 5 - a and b are true 

6、Python成员运算符 
除了以上的一些运算符之外,Python还支持成员运算符,测试实例中包含了一系列的成员,包括字符串,列表或元组。 
 
运算符 描述  实例 
 

in   如果在指定的序列中找到值返回True,否则返回False。   x 在 y序列中 , 如果x在y序列中返回True。 
not in  如果在指定的序列中没有找到值返回True,否则返回False。 x 不在 y序列中 , 如果x不在y序列中返回True。 

Python所有成员运算符的操作: 
 

复制代码 代码示例:
#!/usr/bin/python 
 
a = 10 
b = 20 
list = [1, 2, 3, 4, 5 ]; 
 
if ( a in list ): 
   print "Line 1 - a is available in the given list" 
else: 
   print "Line 1 - a is not available in the given list" 
 
if ( b not in list ): 
   print "Line 2 - b is not available in the given list" 
else: 
   print "Line 2 - b is available in the given list" 
 
a = 2 
if ( a in list ): 
   print "Line 3 - a is available in the given list" 
else: 
   print "Line 3 - a is not available in the given list" 

输出结果: 
Line 1 - a is not available in the given list 
Line 2 - b is not available in the given list 
Line 3 - a is available in the given list 

7、Python身份运算符 
身份运算符用于比较两个对象的存储单元 
运算符 描述  实例 
 

is   is是判断两个标识符是不是引用自一个对象    x is y, 如果 id(x) 等于 id(y) , is 返回结果 1 
is not  is not是判断两个标识符是不是引用自不同对象     x is not y, 如果 id(x) 不等于 id(y). is not 返回结果 1 

Python所有身份运算符的操作: 
 

复制代码 代码示例:
#!/usr/bin/python 
 
a = 20 
b = 20 
 
if ( a is b ): 
   print "Line 1 - a and b have same identity" 
else: 
   print "Line 1 - a and b do not have same identity" 
 
if ( id(a) == id(b) ): 
   print "Line 2 - a and b have same identity" 
else: 
   print "Line 2 - a and b do not have same identity" 
 
b = 30 
if ( a is b ): 
   print "Line 3 - a and b have same identity" 
else: 
   print "Line 3 - a and b do not have same identity" 
 
if ( a is not b ): 
   print "Line 4 - a and b do not have same identity" 
else: 
   print "Line 4 - a and b have same identity" 

输出结果: 
Line 1 - a and b have same identity 
Line 2 - a and b have same identity 
Line 3 - a and b do not have same identity 
Line 4 - a and b do not have same identity  

8、Python运算符优先级 
以下表格列出了从最高到最低优先级的所有运算符: 
运算符 描述 
 

**  指数 (最高优先级) 
~ + -   按位翻转, 一元加号和减号 (最后两个的方法名为 +@ 和 -@) 
* / % //    乘,除,取模和取整除 
+ - 加法减法 
>> <<   右移,左移运算符 
&   位 'AND' 
^ | 位运算符 
<= < > >=   比较运算符 
<> == !=  等于运算符 
= %= /= //= -= += *= **=    赋值运算符 
is is not   身份运算符 
in not in   成员运算符 
not or and  逻辑运算符 

Python所有运算符优先级的操作: 
 

复制代码 代码示例:
#!/usr/bin/python 
 
a = 20 
b = 10 
c = 15 
d = 5 
e = 0 
 
e = (a + b) * c / d       #( 30 * 15 ) / 5 
print "Value of (a + b) * c / d is ",  e 
 
e = ((a + b) * c) / d     # (30 * 15 ) / 5 
print "Value of ((a + b) * c) / d is ",  e 
 
e = (a + b) * (c / d);    # (30) * (15/5) 
print "Value of (a + b) * (c / d) is ",  e 
 
e = a + (b * c) / d;      #  20 + (150/5) 
print "Value of a + (b * c) / d is ",  e 

输出结果: 
Value of (a + b) * c / d is 90 
Value of ((a + b) * c) / d is 90 
Value of (a + b) * (c / d) is 90 
Value of a + (b * c) / d is 50