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This article mainly explains the "what is the use of Python string", the content of the explanation is simple and clear, easy to learn and understand, now please follow the editor's train of thought slowly in depth, together to study and learn "what is the use of Python string" bar!

Str (string)

1. Strings are the most commonly used data type in Python. We can define strings in four ways:'',''and''.

A = 'xperib = "y" c =' xxx'''d = "yyy" print (a recorder bpm c Magi d) # output: x y xxx yyy

two。 Strings are immutable and cannot be changed once they are defined

String = 'world'string =' hello world'

3. Escape of a string

\: line continuation;\ e: escape;\ n: line feeds;\: backslash symbols;\ ": single quotes;\": double quotes;\ 000: empty;\ v: vertical tabs;\ t: horizontal tabs;\ r: carriage returns;\ f: page feeds;\ oyy: octal numbers, characters represented by yy, for example:\ o12 represents line breaks; xyy: hexadecimal numbers, characters represented by yy, for example:\ X0a represents line feeds \ other: other characters are output in normal format

4. Strings can be accessed through index and loop iteration.

# Index access str = 'hello'print (str [1]) # output: e# Loop iterative access str1 =' hello'for item in str1: print (item) # output: hello

5. How to concatenate a string

Use the + sign to connect directly

String1 = 'hello'string2 ='\ t'string3 = 'world'print (string1 + string2 + string3) # output: hello world

Connect using the join method

Lst = ['1percent,' 2percent, '3percent,' 4percent,'5'] lst_new = '.join (lst) print (lst_new) # output: 12345

6. The cutting of strings

Use split (sep=None, maxsplit=num)-> list of strings to cut from left to right, sep specifies the delimiter, maxsplit specifies the number of cuts, and num specifies the number of cuts. If the maxsplit parameter is not set, the number of cuts is unlimited according to sep.

String1 = '1Jing 2j3j1 = string1.split (',') new_obj2 = string1.split (',', maxsplit=1) print (new_obj1) # output: ['1bike,' 2pm, '3pm,' 4pm,'5'] print (new_obj2) # output: ['1pm,' 2Ling 3pm 4pm 4J 5']

Using the rsplit method, rsplit (sep=None, maxsplit=num)-> list of strings, the parameter setting is similar to the split method, except that the rsplit method is cut from right to left

String1 = '1meme 2j3j1j1 = string1.rsplit (',') new_obj2 = string1.rsplit (',', maxsplit=1) print (new_obj1) # output: ['1pm,' 2pm, '3pm,' 4pm,'5'] print (new_obj2) # output: ['1JEI,' 2MET, 3J 4J,'5']

Use the splitlines method, splitlines ([keepends])-> list of strings, newline character ('\ r\ nmarker,\ n') cut, keepends refers to whether to retain the delimiter, True is reserved, False does not retain

String1 ='I love xkd\ nI love xkd'new_obj1 = string1.splitlines () new_obj2 = string1.splitlines (True) print (new_obj1) # output: ['I love xkd','I love xkd'] print (new_obj2) # output: ['I love xkd\ n','I love xkd']

Using the partition method, partition (sep)-> (head, sep, tail) cuts three segments from left to right, with a delimiter in the middle. If you only need to output one of the segments, you can replace the other segments with an underscore

String1 = '1meme 2, 3jue 4j1, seq, new_obj2 = string1.partition (',') print (new_obj1) # output: 1print (seq) # output:, print (new_obj2) # output: 2memoir 3Power4 newcomer obj1, _, _ = string1.partition (',') print (new_obj1) # output: 1

7. String object method

String = 'aBcd abcD' # initialize a string string

All converted to uppercase

Print (string.upper ()) # output: ABCD ABCD

All converted to lowercase

Print (string.lower ()) # output: abcd abcd

Change uppercase to lowercase, lowercase to uppercase.

Print (string.swapcase ()) # output: AbCD ABCd

Capitalize the initials of all words

Print (string.title ()) # output: Abcd Abcd

The first letter of a string is capitalized

Print (string.capitalize ()) # output: Abcd abcd

The center method, center (width [, fillchar])-> str, centers the string, width specifies the width, and fillchar specifies the filled character

Print (string.center (100,'*') output: * aBcd abcD*

The ljust method, ljust (width [, fillchar]), places the string to the left, width specifies the width, and fillchar specifies the filled character

Print (string.ljust (100,'*') output: aBcd abcD*

The rjust method, rjust (width [, fillchar]), places the string to the right, width specifies the width, and fillchar specifies the filled character

Print (string.rjust (100,'*') output: * aBcd abcD

Zfill method, zfill (width)-> str, right aligned print, left filled with 0

Print (string.zfill) output: 00000000000000000000aBcd abcD

8. String modification

Replace method, replace (old, new [, count])-> str, string substitution, old refers to the string to be replaced, new is the replacement string, and count is the specified number of times

String = 'age'print (string.replace (' averse,'z')) # output: zge

The strip method, strip ([chars])-> str, removes the characters at both ends. Chars specifies the characters to be removed, and if chars is not specified, the white space characters are removed.

String = 'age' print (string.strip ()) # output: ageprint (string.strip ()) # output: age

Lstrip: remove the characters on the left, rstrip: remove the characters on the right

Print (string.rstrip ()) # output: ageprint (string.lstrip ()) # output: age

9. String lookup

String = 'helloworld'

Find method, find (sub [, start [, end]])-> int, search from left to right, sub specifies the string to find, [start,end] returns the index for the start and end indexes

Print (string.find ('e')) # output: 1

Index method, index (sub [, start [, end]])-> int, returns the index

Print (string.index ('w')) # output: 5

Count method, count (sub [, start [, end]])-> int, returns the number of characters that appear

Print (string.count ('l')) # output: 3

10. String judgment

String = 'hello' # initialize a string string

Startswith method, startswith (prefix [, start [, end]])-> bool, whether to start with prefix

Print (string.startswith ('')) # output: True

Endswith (suffix [, start [, end]])-> bool, whether it ends with suffix

Print (string.endswith ('x')) # output: False

Whether isalnum () is a letter or a number

Print (string.isalnum ()) # output: True

Whether isalpha () is a letter

Print (string.isalpha ()) # output: True

Whether isdigit () is a number

Print (string.isdecimal ()) # output: False

Whether isdecimal () is decimal

Print (string.isdecimal ()) # output: False

Whether isidentifier () begins with a letter and an underscore

Print (string.isidentifier ()) # output: True

Whether islower () is lowercase

Print (string.islower ()) # output: True

Whether isupper () is uppercase

Print (string.isupper ()) # output: False

Whether isspace () is a full white space character

Print (string.isspace ()) # output: False

11. String formatting

C language style

Print ("I am d"% (100,)) # Front end complement 0print ('I am% s'% 'hello') # string print ('% .3f'% (99.56789)) # keep 3 decimal places print ("I am%-5d"% (20,)) # left align print ("I am% 5d"% (20,)) # align right

Python format style

S.format (* args, * * kwargs)-> str, where args is a tuple, kwargs is a dictionary, and curly braces are placeholders 1: placeholder print ('I am {}, I am in {} '.format (' fish', 'nautical mile')) print ('I am {0}, I am {1} '.format (' fish', 'nautical mile')) print ('I am {1} I am in {0} '.format (' nautical mile', 'fish',) print ('I am {1}, I am {0}'. Format (* ('nautical mile,' fish')) print ('I am {name}, I am in {addr} '.format (name=' fish', addr=' nautical mile')) print ('I am {name}) I specify 100 positions in {addr} '.format (* * {' name':' fish', 'addr':' nautical miles'}) 2: align # specify 100locations, and align print ('{0} + {1} = {2name':' 100} '.format (1d2 Magazine 3)) # specify 100locations and align to the left, and fill in 0print (' {0} + {1} = {2Flt 0100} '.format (1ZOO})) # to specify 100locations elsewhere Center align print ('{0} + {1} = {2: ^ 100} '.format (1meme 2pm 3) # specify 100 locations Center alignment, complement 0print ('{0} + {1} = {2: 0 ^ 100} '.format (1Jing 2) elsewhere ('I don't know') print ("int: {0hex d} bin: {0V b} hex: {0V x} oct: {0V o}" .format (100)) print ("int: {0V d} bin: {0V V B} hex: {0V V x} oct: {0V V O}" .format) Thank you for your reading. The above is the content of "what is the use of Python strings?" after the study of this article, I believe you have a deeper understanding of the use of Python strings, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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