str 方法总结整理
Posted lrtao2010
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#!/usr/bin/env python #Python 3 字符串常用方法 __author__ = "lrtao2010" #capitalize 将字符串的首字符改为大写 # a = "lrtao" # v = a.capitalize() # print(v) # Lrtao #casefold 将字符串所有字符改为小写，功能强大 # a = "LrTao" # v = a.casefold() # print(v) # lrtao #lower 将字符串所有字符改为小写 # a = "LrTao" # v = a.lower() # print(v) # lrtao #upper 将字符全部转成大写 # a = "LrTao" # v = a.upper() # print(v) # LRTAO #center(self, width, fillchar=None) 内容居中，width：总长度（当width<len(s)时没有效果）； # fillchar：空白处填充内容，默认无 # a = "lrtao" # v = a.center(20,‘*‘) # print(v) # *******lrtao******** #ljust(self, width: int, fillchar: str = ...)内容左对齐，右侧填充,不指定默认空白 # a = "lrtao" # v1 = a.ljust(20,‘*‘) # v2 = a.ljust(20) # print(v1) # print(v2) # lrtao*************** # lrtao #rjust(self, width: int, fillchar: str = ...)内容右对齐，左侧填充,不指定默认空白 # a = "lrtao" # v1 = a.rjust(20,‘*‘) # v2 = a.rjust(20) # print(v1) # print(v2) # ***************lrtao # lrtao # zfill(self, width: int) z指zero，用0将字符填充到指定长度(左侧填充) # a = "test" # v = a.zfill(20) # print(v) # 0000000000000000test # a = "test" # v1 = a.rjust(20,‘0‘) # print(v1) # 0000000000000000test #count(self, sub, start=None, end=None) 统计子序列在字符串里出现的次数,包括start，不包括end # a = "lilelili" # v1 = a.count(‘li‘) # v2 = a.count(‘li‘,1) # v3 = a.count(‘li‘,1,6) # print(v1,v2,v3) # 3 2 1 #encode(encoding=‘utf-8‘,errors=‘strict‘) 以encoding指定的编码格式对字符串进行编码 # a = "lilei" # v = a.encode(encoding=‘utf-8‘) # print(v) # b‘lilei‘ # #endswith(self, suffix, start=None, end=None)是否以指定字符串结束,返回值为布尔值 # a = "hello" # v1 = a.endswith(‘o‘) # v2 = a.endswith(‘l‘) # v3 = a.endswith(‘lo‘) # v4 = a.endswith(‘e‘,0,2) # print(v1,v2,v3,v4) # True False True True #startswith(self, prefix: Union[str, Tuple[str, ...]], start: Optional[int] = ...,end: Optional[int] = ...) #是否以指定字符串开始,返回值为布尔值 # a = "hello" # v1 = a.startswith(‘h‘) # v2 = a.startswith(‘e‘) # v3 = a.startswith(‘he‘) # v4 = a.startswith(‘e‘,1,3) # # print(v1,v2,v3,v4) # True False True True #expandtabs 把字符串的tab字符（ ）转化为空格，如果tab转换空格数量没有定义，默认一个tab转换成8个空格 # a = ‘I am tom‘ # v = a.expandtabs(4) # print(v) # I am tom # find(self, sub, start=None, end=None) 返回首次找到子序列的位置，如果没找到，返回 -1 # a = ‘lilei‘ # v1 = a.find(‘l‘) # v2 = a.find(‘l‘,2) # v3 = a.find(‘lei‘,2,4) # print(v1,v2,v3) # 0 2 -1 #index(self, sub, start=None, end=None)返回首次找到子序列的位置，如果没找到程序会报异常 # a = ‘lilei‘ # v = a.index(‘ll‘) # print(v) # Traceback (most recent call last): # v = a.index(‘ll‘) # ValueError: substring not found #rfind(self, sub: str, __start: Optional[int] = ..., __end: Optional[int] = ...) #返回指定子串的最大索引，如果没找到则返回-1，可以指定要开始和结束位置。 # a = ‘lilililili‘ # v1 = a.rfind(‘li‘) # v2 = a.rfind(‘li‘,9) # v3 = a.rfind(‘li‘,2,4) # print(v1,v2,v3) # 8 -1 2 #rindex(self, sub: str, __start: Optional[int] = ..., __end: Optional[int] = ...) #返回指定子串的最大索引，如果没找到则抛异常，可以指定要开始和结束位置。 # a = ‘lilililili‘ # v1 = a.rindex(‘li‘) # v2 = a.rindex(‘li‘,9) # v3 = a.rindex(‘li‘,2,4) # print(v1) # print(v2) # print(v3) # v2 = a.rindex(‘li‘,9) # ValueError: substring not found # # Process finished with exit code 1 #format 字符串格式化 # a = ‘hello ,{name}!hello ,{name2} !‘ # v = a.format(name=‘lilei‘,name2=‘tom‘) # print(v) # hello ,lilei!hello ,tom ! # a = ‘hello,{0}! hello,{1}!‘ # v = a.format(‘lilei‘,‘tom‘) # print(v) # hello,lilei! hello,tom! #format_map(self, mapping) 和format相似，参数为字典形式 # a = ‘hello ,{name}!hello ,{name2} !‘ # v = a.format_map({‘name2‘:‘lilei‘,‘name‘:‘tom‘}) # print(v) # hello ,tom!hello ,lilei ! #isalnum 是否只包含字母或数字,返回值为布尔值 # a = ‘lsL123‘ # b = ‘ls‘ # c = ‘LS‘ # d = ‘123‘ # e = ‘[email protected]‘ # v1 = a.isalnum() # v2 = b.isalnum() # v3 = c.isalnum() # v4 = d.isalnum() # v5 = e.isalnum() # print(v1,v2,v3,v4,v5) # True True True True False #isalpha 字符串是否全部是字母 # a = ‘lsL123‘ # b = ‘ls‘ # c = ‘LS‘ # d = ‘Ls‘ # e = ‘[email protected]‘ # v1 = a.isalpha() # v2 = b.isalpha() # v3 = c.isalpha() # v4 = d.isalpha() # v5 = e.isalpha() # print(v1,v2,v3,v4,v5) # False True True True False #isascii Return True if all characters in the string are ASCII, False otherwise. # a = ‘12ls er$%^&*()‘ # b = ‘中‘ # v1 = a.isascii() # v2 = b.isascii() # print(v1,v2) # True False #isdecimal 字符串是否是十进制字符串 # a = ‘1234567890‘ # b = ‘A0‘ # v1 = a.isdecimal() # v2 = b.isdecimal() # print(v1,v2) # True False #isdigit 如果字符串是数字字符串，则返回True，否则返回False。 # isdecimal() 如果字符串是数字字符串，则返回True，否则返回False。 #isnumeric 如果字符串是数字字符串，则返回True，否则返回False # num = "一" # v1 = num.isdigit() # v2 = num.isdecimal() # v3 = num.isnumeric() # print(v1,v2,v3) # False False True # num = "Ⅰ" #罗马数字1 # v1 = num.isdigit() # v2 = num.isdecimal() # v3 = num.isnumeric() # print(v1,v2,v3) # False False True # num = "1" # v1 = num.isdigit() # v2 = num.isdecimal() # v3 = num.isnumeric() # print(v1,v2,v3) # True True True # isdigit() # True: Unicode数字,byte数字（单字节）,全角数字（双字节）,罗马数字 # False: 汉字数字 # Error: 无 # isdecimal() # True: Unicode数字,全角数字（双字节） # False: 罗马数字,汉字数字 # Error: byte数字（单字节） # isnumeric() # True: Unicode数字,全角数字（双字节）,罗马数字,汉字数字 # False: 无 # Error: byte数字（单字节） #isidentifier 判断字符串是否包含python的保留字 # v1 = ‘def‘.isidentifier() # v2 = ‘aaa‘.isdecimal() # print(v1,v2) # True False #islower 字符串中不能出现大写字母，并且至少有一个小写字母 # a = ‘ls12#3‘ # b = ‘Ls‘ # c = ‘1234s‘ # d = ‘LS‘ # v1 = a.islower() # v2 = b.islower() # v3 = c.islower() # v4 = d.islower() # print(v1,v2,v3,v4) # True False True False #isprintable 判断字符串中所有的字符串都是可以通过repr表示成字符串， # 或者字符串是空的，都返回True,否则返回False # v = chr(33).isprintable() # v1 = chr(1000000).isprintable() # print(v,v1) # True False #isspace 判断字符串是否是空格 # a = ‘‘ # b = ‘ ‘ # v1 = a.isspace() # v2 = b.isspace() # print(v1,v2) # False True #title 标题格式(可以理解为单词首字母大写，其它字符小写) # a = ‘this is title‘ # v = a.title() # print(v) # This Is Title #istitle 判断是否是标题格式（可以理解为首字母是否大写） # a = "this is title" # b = "This is title" # c = "This Is title" # d = "This Is Title" # v1 = a.istitle() # v2 = b.istitle() # v3 = c.istitle() # v4 = d.istitle() # print(v1,v2,v3,v4) # False False False True #isupper 判断字母是否全部是大写 # a = ‘lsL123‘ # b = ‘LSF123‘ # c = ‘LSF‘ # d = ‘LS F‘ # v1 = a.isupper() # v2 = b.isupper() # v3 = c.isupper() # v4 = d.isupper() # print(v1,v2,v3,v4) # False True True True #join(self, iterable: Iterable[str])返回一个用指定分隔符分隔的字， # 或者是将指定字符加入到另一个字符中。 # a = ‘iamtom‘ # v1 = ‘.‘.join(a) # v2 = ‘#‘.join(a) # print(v1) # print(v2) # i.a.m.t.o.m # i#a#m#t#o#m #lstrip 移除左侧空白(没有测试成功) #partition(self, sep: str) 按照指定的字符将字符串分为前中后三部分,从左侧开始 # a = "iamtom" # v1 = a.partition("i") # v2 = a.partition(‘am‘) # v3 = a.partition(‘om‘) # v4 = a.partition(‘som‘) # print(v1) # print(v2) # print(v3) # print(v4) # (‘‘, ‘i‘, ‘amtom‘) # (‘i‘, ‘am‘, ‘tom‘) # (‘iamt‘, ‘om‘, ‘‘) # (‘iamtom‘, ‘‘, ‘‘) #rpartition(self, sep: str) 与partition一样，但是从右边开始 # a = "iamtom" # v1 = a.rpartition("i") # v2 = a.rpartition(‘am‘) # v3 = a.rpartition(‘tom‘) # v4 = a.rpartition(‘som‘) # print(v1) # print(v2) # print(v3) # print(v4) # (‘‘, ‘i‘, ‘amtom‘) # (‘i‘, ‘am‘, ‘tom‘) # (‘iam‘, ‘tom‘, ‘‘) # (‘‘, ‘‘, ‘iamtom‘) #replace(self, old: str, new: str, count: int = ...) 替换字符，不指定次数默认全部替换 # a = ‘iamtomtomtom‘ # v1 = a.replace(‘m‘,‘i‘) # v2 = a.replace(‘m‘,‘i‘,1) # print(v1) # print(v2) # iaitoitoitoi # iaitomtomtom #split(self, sep: Optional[str] = ..., maxsplit: int = ...) #按指定字符串从左侧开始进行切割，可以指定切割次数(不指定全部切割) # a = ‘iamtomtom‘ # v1 = a.split(‘m‘) # v2 = a.split(‘m‘,2) # print(v1) # print(v2) # [‘ia‘, ‘to‘, ‘to‘, ‘‘] # [‘ia‘, ‘to‘, ‘tom‘] #rsplit(self, sep: Optional[str] = ..., maxsplit: int = ...) #按指定字符串从右侧开始进行切割，可以指定切割次数(不指定全部切割) # a = ‘iamtomtom‘ # v1 = a.rsplit(‘m‘) # v2 = a.rsplit(‘m‘,2) # print(v1) # print(v2) # [‘ia‘, ‘to‘, ‘to‘, ‘‘] # [‘iamto‘, ‘to‘, ‘‘] #strip(self, chars: Optional[str] = ...) #移除两侧（最外侧）指定字符串，默认移除空格，以指定多个字符 # a = ‘ i am tom m‘ # v1 = a.strip() # v2 = a.strip(‘m‘) # v3 = a.strip(‘ap‘) # v4 = a.strip(‘am‘) # print(v1) # print(v2) # print(v3) # print(v4) # i am tom m # i am tom # i am tom m # i am tom #rstrip(self, chars: Optional[str] = ...) #移除右侧指定字符 # a = ‘ i am tom m‘ # v1 = a.rstrip() # v2 = a.rstrip(‘m‘) # v3 = a.rstrip(‘ap‘) # v4 = a.rstrip(‘am‘) # print(v1) # print(v2) # print(v3) # print(v4) # i am tom m # i am tom # i am tom m # i am tom #splitlines(self, keepends: bool = ...) #按换行符 切割，如果没指定keepends=True，则会将其从结果中移除 # a = "this is test1 this is test2" # v1 = a.splitlines(keepends=True) # v2 = a.splitlines() # print(v1) # print(v2) # [‘this is test1 ‘, ‘ this is test2‘] # [‘this is test1‘, ‘ this is test2‘] #swapcase 大小写转换 # a = ‘This Is Test 01‘ # v = a.swapcase() # print(v) # tHIS iS tEST 01 #translate(self, table: Optional[bytes], delete: bytes = ...) #translate() 方法根据参数table给出的表(包含 256 个字符)转换字符串的字符, # 要过滤掉的字符放到 deletechars 参数中 # intab = "aeiou" # outtab = "12345" # trantab = str.maketrans(intab, outtab) # 制作翻译表 # str = "this is string example....wow!!!" # print(str.translate(trantab)) # th3s 3s str3ng 2x1mpl2....w4w!!! # 制作翻译表 # bytes_tabtrans = bytes.maketrans(b‘abcdefghijklmnopqrstuvwxyz‘, b‘ABCDEFGHIJKLMNOPQRSTUVWXYZ‘) # # # 转换为大写，并删除字母o # print(b‘runoob‘.translate(bytes_tabtrans, b‘o‘)) # b‘RUNB‘
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