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• Python character string

Python character string

Python in , In addition to using some built-in functions to obtain information about strings （ for example len() Function to get the length of the string ）, The string type itself has some methods for us to use .

Be careful , The method here , Refers to the string type str What it provides , Because of the knowledge of classes and objects , Beginners don't have to delve into , Just know the specific usage of the method .
From this section on , We will introduce some common string type methods , This section first introduces the method of splitting strings split() Method .

split() Method can be used to cut a string into multiple substrings according to the specified separator , These substrings are saved to the list （ Does not contain separators ）, Feedback back as the return value of the method . The basic syntax format of this method is as follows ：

str.split(sep,maxsplit)

The meanings of the parameters in this method are respectively ：

• str： Represents the string to be split ;
• sep： Used to specify separator , Can contain multiple characters . This parameter defaults to None, Indicates all empty characters , Including Spaces 、 A newline “\n”、 tabs “\t” etc. .
• maxsplit： Optional parameters , Used to specify the number of divisions , The number of substrings in the final list is at most maxsplit+1. If not specified or designated as -1, It means that there is no limit to the number of segmentation .

stay split In the method , If you don't specify sep Parameters , Need to be str.split(maxsplit=xxx) The format of maxsplit Parameters .

Same as built-in function （ Such as len） It's used in different ways , Methods owned by string variables , Only use “ character string . Method name ()” Method call . There's no need to worry about why , After learning classes and objects , It's natural to understand .

for example , Define a save C Language: the string of Chinese web address , And then use split() Method is separated according to different delimiters , The execution process is as follows ：

>>> str = "C Chinese language network >>> c.biancheng.net"
>>> str
'C Chinese language network >>> c.biancheng.net'
>>> list1 = str.split() # Split with default separator 
>>> list1
['C Chinese language network ', '>>>', 'c.biancheng.net']
>>> list2 = str.split('>>>') # Use multiple characters for segmentation 
>>> list2
['C Chinese language network ', ' c.biancheng.net']
>>> list3 = str.split('.') # use . No split 
>>> list3
['C Chinese language network >>> c', 'biancheng', 'net']
>>> list4 = str.split(' ',4) # Use spaces to divide , And stipulates that it can only be divided into 4 Substring 
>>> list4
['C Chinese language network ', '>>>', 'c.biancheng.net']
>>> list5 = str.split('>') # use > Character segmentation 
>>> list5
['C Chinese language network ', '', '', ' c.biancheng.net']
>>>

It should be noted that , In unspecified sep When parameters are ,split() Method uses null characters for segmentation by default , But when there are consecutive spaces or other empty characters in the string , Will be treated as a separator to split the string , for example ：

>>> str = "C Chinese language network >>> c.biancheng.net" # contain 3 Consecutive spaces 
>>> list6 = str.split()
>>> list6
['C Chinese language network ', '>>>', 'c.biancheng.net']
>>>