运算符

• +

>>> "hello " + "itcast"
'hello itcast'
>>> [1, 2] + [3, 4]
[1, 2, 3, 4]
>>> ('a', 'b') + ('c', 'd')
('a', 'b', 'c', 'd')

  

 

  
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• *

>>> 'ab'*4
'ababab'
>>> [1, 2]*4
[1, 2, 1, 2, 1, 2, 1, 2]
>>> ('a', 'b')*4
('a', 'b', 'a', 'b', 'a', 'b', 'a', 'b')

  

 

  
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• in

>>> 'itc' in 'hello itcast'
True
>>> 3 in [1, 2]
False
>>> 4 in (1, 2, 3, 4)
True
>>> "name" in {"name":"Delron", "age":24}
True

  

 

  
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注意，in在对字典操作时，判断的是字典的键

python内置函数
Python包含了以下内置函数

• cmp

>>> cmp("hello", "itcast")
-1
>>> cmp("itcast", "hello")
1
>>> cmp("itcast", "itcast")
0
>>> cmp([1, 2], [3, 4])
-1
>>> cmp([1, 2], [1, 1])
1
>>> cmp([1, 2], [1, 2, 3])
-1
>>> cmp({"a":1}, {"b":1})
-1
>>> cmp({"a":2}, {"a":1})
1
>>> cmp({"a":2}, {"a":2, "b":1})
-1

  

 

  
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注意：cmp在比较字典数据时，先比较键，再比较值。

• len

>>> len("hello itcast")
12
>>> len([1, 2, 3, 4])
4
>>> len((3,4))
2
>>> len({"a":1, "b":2})
2

  

 

  
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注意：len在操作字典数据时，返回的是键值对个数。

• max

>>> max("hello itcast")
't'
>>> max([1,4,522,3,4])
522
>>> max({"a":1, "b":2})
'b'
>>> max({"a":10, "b":2})
'b'
>>> max({"c":10, "b":2})
'c'

  

 

  
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• del
  del有两种用法，一种是del加空格，另一种是del()

>>> a = 1
>>> a
1
>>> del a
>>> a

  

 

  
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Traceback (most recent call last):
File “”, line 1, in
NameError: name ‘a’ is not defined

>>> a = ['a', 'b']
>>> del a[0]
>>> a
['b']
>>> del(a)
>>> a

  

 

  
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Traceback (most recent call last):
File “”, line 1, in
NameError: name ‘a’ is not defined

多维列表/元祖访问的示例

>>> tuple1 = [(2,3),(4,5)]
>>> tuple1[0]
(2, 3)
>>> tuple1[0][0]
2
>>> tuple1[0][2]

  

 

  
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Traceback (most recent call last):
File “”, line 1, in
IndexError: tuple index out of range

>>> tuple1[0][1]
3
>>> tuple1[2][2]

  

 

  
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Traceback (most recent call last):
File “”, line 1, in
IndexError: list index out of range

>>> tuple2 = tuple1+[(3)]
>>> tuple2
[(2, 3), (4, 5), 3]
>>> tuple2[2]
3
>>> tuple2[2][0]

  

 

  
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Traceback (most recent call last):
File “”, line 1, in
TypeError: ‘int’ object is not subscriptable

文章来源: yujiang.blog.csdn.net，作者：鱼酱2333，版权归原作者所有，如需转载，请联系作者。

原文链接：yujiang.blog.csdn.net/article/details/89322169