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python中字符串內(nèi)置函數(shù)的用法總結(jié)

 更新時(shí)間：2018年09月13日 14:39:08   投稿：laozhang  
這篇文章給大家總結(jié)了python中字符串內(nèi)置函數(shù)的用法以及相關(guān)知識(shí)點(diǎn)內(nèi)容，有興趣的朋友學(xué)習(xí)下。

capitalize（） 首字母大寫

a='someword' 
 b=a.capitalize() 
 print(b) 
 —>Someword

casefold()&lower() 所有字母變小寫，casefold可將未知字符便小寫

a='someWORD' 
  b=a.casefold() 
  print(b) 
  c=a.lower() 
  print(c) 
  —>someword 
  —>someword

center(width,fillchar=None) 設(shè)置寬度，并將內(nèi)容居中，空白未知填充，一個(gè)字符

a='someword' 
  b=a.center(30,'*') 
  print(b)

count(sub,start=None,end=None) 去字符串中尋找，尋找子序列的出現(xiàn)次數(shù)，可指定起止點(diǎn)

a='somewordsomeword' 
 b=a.count(‘or') 
 print(b) 
 —>2

startswith(suffix,start=None,end=None)&endswith(suffix,start=None,end=None) 是否以XX開始/結(jié)束，可指定起止點(diǎn)

a='somewordsomeword' 
  b=a.startswith(‘sa') 
  c=a.endswith(‘ord') 
  print(b) 
  print(c) 
  —>False 
  —>True

find(sub,start=None,end=None) 尋找指定字符或字符串，并返回第一個(gè)位置，找不到返回-1，可指定起止點(diǎn)

a='somewordsomeword' 
  b=a.find(‘me') 
  print(b) 
  —>2

format() 格式化，將一個(gè)字符串中的占位符替換為指定的值

test='I am {name},age {a}' 
  v=test.format(name='alex',a=19) 
  print(v) 
  —>i am alex,age 19

format_map() 格式化，傳入的值

test='iam{name},age{a}' 
  v=test.format_map({“name”:'alex',”a”:19}) 
  print(v) 
  —>i am alex,age 19

isalnum() 字符串中是否只包含字母和數(shù)字

a='asdfs123*' 
  b=a.isalnum() 
  print(b) 
  —>False

expandtabs(tabsize=number) 將字符串以number分割，并將tab補(bǔ)入

a='asdfs123\t523fgbdf' 
 b=a.expandtabs(5) 
 print(b)
 —>asdfs123 523fgbdf

isalpha() 字符串中是只包含字母

a='asdfsfgbdf' 
 b=a.isalpha() 
 print(b) 
 —>True

isdecimal()&isdigit()&isnumeric() 字符串中是只包含數(shù)字，isdigit更為強(qiáng)大，isnumeric還可識(shí)別中文

a='132132②二' 
  b=a.isdecimal() 
  c=a.isdigit() 
  d=a.isnumeric() 
  print(b) 
  print(c) 
  print(d) 
  —>False 
  —>False 
  —>True

isprintable() 是否存在不可顯示的字符如換行符

a='sdfgdfg\t' 
 b=a.isprintable() 
 print(b) 
 —>False

isspace() 判斷是否全部為空格

a='dsvsdv' 
  b=a.isspace() 
  print(b) 
  —>False

istitle()&title() 判斷是否為標(biāo)題，即首字母大寫&變?yōu)闃?biāo)題

a='follow uncased characters and lowercase characters only cased ones' 
  b=a.istitle() 
  print(b) 
  c=a.title() 
  print(c) 
  —>False 
  —>Follow Uncased Characters And Lowercase Characters Only Cased Ones

join(iterable) 將字符串中的每個(gè)元素按照指定分隔符進(jìn)行拼接

a='一二三四五六七' 
  print(a) 
  b='*' 
  c=b.join(a) 
  print(c) 
  —>一二三四五六七 
  —>一二三四五六七

ljust(width,fillchar=None)&rjust(width,fillchar=None) 向右/左填充字符

a='hello' 
 b=a.ljust(20,'*') 
 c=a.rjust(20,'*') 
 print(b) 
 print(c) 
 —>hello*************** 
 —>***************hello

islower()&lower() 判斷是是否為全小寫&變?yōu)槿啃?/p> 

a='Hello' 
  b=a.islower() 
  c=a.lower() 
  print(b,c) 
  —>False hello

isupper()&c=a.upper() 判斷是是否為全大寫&變?yōu)槿看髮?/p> 

a='Hello' 
  b=a.isupper() 
  c=a.upper() 
  print(b,c) 
  —>False HELLO

lstrip(chars=None)&rstrip(chars=None)&strip(chars=None) 去除字符串左邊/右邊/兩邊的字符串，默認(rèn)空格，換行等

a='Hello' 
  b=a.lstrip() 
  c=a.rstrip() 
  d=a.strip() 
  print(b) 
  print(c) 
  print(d) 
  —>Hello 
  —> Hello 
  —>Hello

maketrans(*args,**kwargs)&translate(table) 按maketrans對(duì)應(yīng)關(guān)系將translate中的字符串進(jìn)行替換

a='asdgfrfbcvzxrentas' 
  b=str.maketrans(‘xdsa','1234') 
  c=a.translate(b) 
  print(c) 
  —> 432gfrfbcvz1rent43

partition(sep)&rpartition(sep) 將字符串按指定字符分割成3段/或從右開始

a='helwloasvxcwaewc' 
  b=a.partition(‘w') 
  c=a.rpartition(‘w') 
  print(b) 
  print(c) 
  —>(‘hel', ‘w', ‘loasvxcwaewc') 
  —>(‘helwloasvxcwae', ‘w', ‘c')

split(sep=None,maxsplit=-1)&rsplit(sep=None,maxsplit=-1) 將字符串按指定字符串分割，分割后不保留

a='helwloasvxcwaewc' 
  b=a.split(‘w',2) 
  c=a.rsplit(‘w') 
  print(b) 
  print(c) 
  —>[‘hel', ‘loasvxc', ‘a(chǎn)ewc'] 
  —>[‘hel', ‘loasvxc', ‘a(chǎn)e', ‘c']

splitlines(keepends=None) 按照換行符進(jìn)行分割，帶true參數(shù)保留換行符

a='helwloas\nvxcwaewc\nafgasdfs' 
  b=a.splitlines() 
  c=a.splitlines(True) 
  print(b) 
  print(c) 
  —>[‘helwloas', ‘vxcwaewc', ‘a(chǎn)fgasdfs'] 
  —>[‘helwloas\n', ‘vxcwaewc\n', ‘a(chǎn)fgasdfs']

startswith(prefix,start=None,end=None)&endswith(prefix,start=None,end=None) 判斷字符串是否以指定字符開始/結(jié)束，可指定起止點(diǎn)

a='aefsfsfeeav' 
  b=a.startswith(‘a(chǎn)e') 
  c=a.endswith(‘a(chǎn)v',1,9) 
  print(b) 
  print(c) 
  True 
  —>False

swapcase() 小寫轉(zhuǎn)變?yōu)榇髮?/p> 

a='aefsfsfeeav' 
  b=a.swapcase() 
  print(b) 
  —>AEFSFSFEEAV

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