python中字符串内置函数的用法总结
capitalize（）首字母大写
a='someword' b=a.capitalize() print(b) —>Someword
casefold()&lower()所有字母变小写，casefold可将未知字符便小写
a='someWORD' b=a.casefold() print(b) c=a.lower() print(c) —>someword —>someword
center(width,fillchar=None)设置宽度，并将内容居中，空白未知填充，一个字符
a='someword' b=a.center(30,'*') print(b)
count(sub,start=None,end=None)去字符串中寻找，寻找子序列的出现次数，可指定起止点
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开始/结束，可指定起止点
a='somewordsomeword' b=a.startswith(‘sa') c=a.endswith(‘ord') print(b) print(c) —>False —>True
find(sub,start=None,end=None)寻找指定字符或字符串，并返回第一个位置，找不到返回-1，可指定起止点
a='somewordsomeword' b=a.find(‘me') print(b) —>2
format()格式化，将一个字符串中的占位符替换为指定的值
test='Iam{name},age{a}'
v=test.format(name='alex',a=19)
print(v)
—>iamalex,age19
format_map()格式化，传入的值
test='iam{name},age{a}'
v=test.format_map({“name”:'alex',”a”:19})
print(v)
—>iamalex,age19
isalnum()字符串中是否只包含字母和数字
a='asdfs123*' b=a.isalnum() print(b) —>False
expandtabs(tabsize=number)将字符串以number分割，并将tab补入
a='asdfs123\t523fgbdf' b=a.expandtabs(5) print(b) —>asdfs123523fgbdf
isalpha()字符串中是只包含字母
a='asdfsfgbdf' b=a.isalpha() print(b) —>True
isdecimal()&isdigit()&isnumeric()字符串中是只包含数字，isdigit更为强大，isnumeric还可识别中文
a='132132②二' b=a.isdecimal() c=a.isdigit() d=a.isnumeric() print(b) print(c) print(d) —>False —>False —>True
isprintable()是否存在不可显示的字符如换行符
a='sdfgdfg\t' b=a.isprintable() print(b) —>False
isspace()判断是否全部为空格
a='dsvsdv' b=a.isspace() print(b) —>False
istitle()&title()判断是否为标题，即首字母大写&变为标题
a='followuncasedcharactersandlowercasecharactersonlycasedones' b=a.istitle() print(b) c=a.title() print(c) —>False —>FollowUncasedCharactersAndLowercaseCharactersOnlyCasedOnes
join(iterable)将字符串中的每个元素按照指定分隔符进行拼接
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()判断是是否为全小写&变为全部小写
a='Hello' b=a.islower() c=a.lower() print(b,c) —>Falsehello
isupper()&c=a.upper()判断是是否为全大写&变为全部大写
a='Hello' b=a.isupper() c=a.upper() print(b,c) —>FalseHELLO
lstrip(chars=None)&rstrip(chars=None)&strip(chars=None)去除字符串左边/右边/两边的字符串，默认空格，换行等
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对应关系将translate中的字符串进行替换
a='asdgfrfbcvzxrentas' b=str.maketrans(‘xdsa','1234') c=a.translate(b) print(c) —>432gfrfbcvz1rent43
partition(sep)&rpartition(sep)将字符串按指定字符分割成3段/或从右开始
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)将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',‘aewc'] —>[‘hel',‘loasvxc',‘ae',‘c']
splitlines(keepends=None)按照换行符进行分割，带true参数保留换行符
a='helwloas\nvxcwaewc\nafgasdfs' b=a.splitlines() c=a.splitlines(True) print(b) print(c) —>[‘helwloas',‘vxcwaewc',‘afgasdfs'] —>[‘helwloas\n',‘vxcwaewc\n',‘afgasdfs']
startswith(prefix,start=None,end=None)&endswith(prefix,start=None,end=None)判断字符串是否以指定字符开始/结束，可指定起止点
a='aefsfsfeeav' b=a.startswith(‘ae') c=a.endswith(‘av',1,9) print(b) print(c) True —>False
swapcase()小写转变为大写
a='aefsfsfeeav' b=a.swapcase() print(b) —>AEFSFSFEEAV