python 字符串创建，遍历，切片，格式化ljust rjust center,find,replace,split,repr,str

python 字符串创建，遍历，切片，格式化ljust rjust center

s = "abcdef"

遍历字符串

for i in [None] + range(-1,-len(s),-1):  每次比上一次上一个字符     print s[:i]abcdefabcdeabcdabcabaprint s[2:-1] 

字符串对齐

print s.center(50,'*')    字符占宽度50,中间对齐，用*填充print s.ljust(50,'-')     字符占宽度50，左对齐，用-填充print s.rjust(50,'%')     字符占宽度50，右对齐，用%填充**********************abcdef**********************abcdef--------------------------------------------%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%abcdef

字符串操作

s1 += s2s1 > s2s1 == s2

字符与ascii 之间的转化

chr(65) ascii为65的字符ord('a') 字符a的ascii 

格式化输出

%s 转换成字符串%d 十进制整数%.2f 小数点后面2位%x 16进制% 字典输出d = {'name':'xiaoming','age':16}print '%(name)s  %(age)s'%(d)

str的帮助 (help(str)

>>> help(str)Help on class str in module __builtin__:class str(basestring) |  str(object) -> string |   |  Return a nice string representation of the object. |  If the argument is a string, the return value is the same object. |   |  Method resolution order: |      str |      basestring |      object |   |  Methods defined here: |   |  __add__(...) |      x.__add__(y) <==> x+y>>> a = "hello">>> b = "world">>> a + b 'helloworld'>>>  |   |  __contains__(...) |      x.__contains__(y) <==> y in xc = a + b a in c  ==>True |   |  __eq__(...) |      x.__eq__(y) <==> x==y | a = "hello">>> b = "hello"  a == b  ==>True |  __format__(...) |      S.__format__(format_spec) -> string |       |      Return a formatted version of S as described by format_spec. |   |  __ge__(...) |      x.__ge__(y) <==> x>=y |  a = "hello">>> b = "world"    a > b ==>False |  __getattribute__(...) |      x.__getattribute__('name') <==> x.name |   |  __getitem__(...) |      x.__getitem__(y) <==> x[y] |   |  __getnewargs__(...) |   |  __getslice__(...) |      x.__getslice__(i, j) <==> x[i:j] |       |      Use of negative indices is not supported. |  a[1:3] ⇒ 'el' |  __gt__(...) |      x.__gt__(y) <==> x>y |  a > b ==>False |  __hash__(...) |      x.__hash__() <==> hash(x) |   |  __le__(...) |      x.__le__(y) <==> x<=y |  a <= b ==>True |  __len__(...) |      x.__len__() <==> len(x) |  len(a)  ⇒ 5 |  __lt__(...) |      x.__lt__(y) <==> x<y |  a < b ==>True |  __mod__(...) |      x.__mod__(y) <==> x%y |   |  __mul__(...) |      x.__mul__(n) <==> x*n |a * 5'hellohellohellohellohello'   |  __ne__(...) |      x.__ne__(y) <==> x!=y |  a != bTrue |  __repr__(...) |      x.__repr__() <==> repr(x) |  repr(a)"'hello'" |  __rmod__(...) |      x.__rmod__(y) <==> y%x |   |  __rmul__(...) |      x.__rmul__(n) <==> n*x |   |  __sizeof__(...) |      S.__sizeof__() -> size of S in memory, in bytes |   |  __str__(...) |      x.__str__() <==> str(x) |  str(a)'hello' |  capitalize(...) |      S.capitalize() -> string |a.capitalize()'Hello'       |      Return a copy of the string S with only its first character |      capitalized. |   |  center(...) |      S.center(width[, fillchar]) -> string |  a.center(50,'*')'**********************hello***********************'     |      Return S centered in a string of length width. Padding is |      done using the specified fill character (default is a space) |   |  count(...) |      S.count(sub[, start[, end]]) -> int |       |      Return the number of non-overlapping occurrences of substring sub in |      string S[start:end].  Optional arguments start and end are interpreted |      as in slice notation. a= "helloho" |  a.count('h')2 |  decode(...) |      S.decode([encoding[,errors]]) -> object |       |      Decodes S using the codec registered for encoding. encoding defaults |      to the default encoding. errors may be given to set a different error |      handling scheme. Default is 'strict' meaning that encoding errors raise |      a UnicodeDecodeError. Other possible values are 'ignore' and 'replace' |      as well as any other name registered with codecs.register_error that is |      able to handle UnicodeDecodeErrors. |   |  encode(...) |      S.encode([encoding[,errors]]) -> object |       |      Encodes S using the codec registered for encoding. encoding defaults |      to the default encoding. errors may be given to set a different error |      handling scheme. Default is 'strict' meaning that encoding errors raise |      a UnicodeEncodeError. Other possible values are 'ignore', 'replace' and |      'xmlcharrefreplace' as well as any other name registered with |      codecs.register_error that is able to handle UnicodeEncodeErrors. |   |  endswith(...) |      S.endswith(suffix[, start[, end]]) -> bool |       |      Return True if S ends with the specified suffix, False otherwise. |      With optional start, test S beginning at that position. |      With optional end, stop comparing S at that position. |      suffix can also be a tuple of strings to try.a.endswith("ho") ==>True |   |  expandtabs(...) |      S.expandtabs([tabsize]) -> string |       |      Return a copy of S where all tab characters are expanded using spaces. |      If tabsize is not given, a tab size of 8 characters is assumed. |   |  find(...)a.find("ho")5 |      S.find(sub [,start [,end]]) -> int |       |      Return the lowest index in S where substring sub is found, |      such that sub is contained within S[start:end].  Optional |      arguments start and end are interpreted as in slice notation. |       |      Return -1 on failure. |   |  format(...) |      S.format(*args, **kwargs) -> string |       |      Return a formatted version of S, using substitutions from args and kwargs. |      The substitutions are identified by braces ('{' and '}'). |   |  index(...) |      S.index(sub [,start [,end]]) -> int |       |      Like S.find() but raise ValueError when the substring is not found. a.index("h")0 |   |  isalnum(...) |      S.isalnum() -> bool |       |      Return True if all characters in S are alphanumeric |      and there is at least one character in S, False otherwise. |  a = "99hhhhxx\t">>> a.isalnum()False |  isalpha(...) |      S.isalpha() -> bool |       |      Return True if all characters in S are alphabetic |      and there is at least one character in S, False otherwise. |   |  isdigit(...) |      S.isdigit() -> bool |       |      Return True if all characters in S are digits |      and there is at least one character in S, False otherwise. |  a = "0123456789">>> a.isdigit()True |  islower(...) |      S.islower() -> bool |       |      Return True if all cased characters in S are lowercase and there is |      at least one cased character in S, False otherwise. |  a = "aaaaa13455">>> a.islower()True |  isspace(...) |      S.isspace() -> bool |       |      Return True if all characters in S are whitespace |      and there is at least one character in S, False otherwise. |  a.isspace()False |  istitle(...) |      S.istitle() -> bool |  a.title()  'Aaaaa13455'a.istitle()     |      Return True if S is a titlecased string and there is at least one |      character in S, i.e. uppercase characters may only follow uncased |      characters and lowercase characters only cased ones. Return False |      otherwise. |   |  isupper(...) |      S.isupper() -> bool |   a.isupper() False    |      Return True if all cased characters in S are uppercase and there is |      at least one cased character in S, False otherwise. |   |  join(...) |      S.join(iterable) -> string |       |      Return a string which is the concatenation of the strings in the |      iterable.  The separator between elements is S. |   c = ["aa","bb","cc"]>>> ','.join(c)'aa,bb,cc' |  ljust(...) |      S.ljust(width[, fillchar]) -> string |       |      Return S left-justified in a string of length width. Padding is |      done using the specified fill character (default is a space). |  a.ljust(100,'*')'hello,world*****************************************************************************************' |  lower(...) |      S.lower() -> string |       |      Return a copy of the string S converted to lowercase. |  a = string.uppercase>>> a'ABCDEFGHIJKLMNOPQRSTUVWXYZ'>>> a.lower()'abcdefghijklmnopqrstuvwxyz'>>>  |  lstrip(...) |      S.lstrip([chars]) -> string or unicode |       |      Return a copy of the string S with leading whitespace removed. |      If chars is given and not None, remove characters in chars instead. |      If chars is unicode, S will be converted to unicode before strippinga = "      hello world    ">>> a.lstrip()'hello world    '>>>  |   |  partition(...) |      S.partition(sep) -> (head, sep, tail) |       |      Search for the separator sep in S, and return the part before it, |      the separator itself, and the part after it.  If the separator is not |      found, return S and two empty strings. |   |  replace(...) |      S.replace(old, new[, count]) -> string |       |      Return a copy of string S with all occurrences of substring |      old replaced by new.  If the optional argument count is |      given, only the first count occurrences are replaced.a = "abcde">>> a.replace('c','H***H')'abH***Hde'>>>  |   |  rfind(...) |      S.rfind(sub [,start [,end]]) -> int |       |      Return the highest index in S where substring sub is found, |      such that sub is contained within S[start:end].  Optional |      arguments start and end are interpreted as in slice notation. |       |      Return -1 on failure. >>> a = "abcdea">>> a.find('a')0>>> a.rfind('a')5 |   |  rindex(...) |      S.rindex(sub [,start [,end]]) -> int |       |      Like S.rfind() but raise ValueError when the substring is not found.>>> a.index('a')0>>> a.rindex('a')5>>>  |   |  rjust(...) |      S.rjust(width[, fillchar]) -> string |       |      Return S right-justified in a string of length width. Padding is |      done using the specified fill character (default is a space)>>> a.rjust(100,"*")'**********************************************************************************************abcdea'>>>  |   |  rpartition(...) |      S.rpartition(sep) -> (head, sep, tail) |       |      Search for the separator sep in S, starting at the end of S, and return |      the part before it, the separator itself, and the part after it.  If the |      separator is not found, return two empty strings and S. |   |  rsplit(...) |      S.rsplit([sep [,maxsplit]]) -> list of strings |       |      Return a list of the words in the string S, using sep as the |      delimiter string, starting at the end of the string and working |      to the front.  If maxsplit is given, at most maxsplit splits are |      done. If sep is not specified or is None, any whitespace string |      is a separator. >>> str1 = "a,b,c,d,e,f,">>> str1.rsplit(',',1)['a,b,c,d,e,f', '']>>> |   |  rstrip(...) |      S.rstrip([chars]) -> string or unicode |       |      Return a copy of the string S with trailing whitespace removed. |      If chars is given and not None, remove characters in chars instead. |      If chars is unicode, S will be converted to unicode before stripping>>> str1 = "     Helo,wollll    ">>> str1.rstrip()'     Helo,wollll'>>> |   |  split(...) |      S.split([sep [,maxsplit]]) -> list of strings |       |      Return a list of the words in the string S, using sep as the |      delimiter string.  If maxsplit is given, at most maxsplit |      splits are done. If sep is not specified or is None, any |      whitespace string is a separator and empty strings are removed |      from the result.>>> str1 = "a,b,c,d,e,f,">>> str1.split()['a,b,c,d,e,f,']>>>  |   |  splitlines(...) |      S.splitlines([keepends]) -> list of strings |       |      Return a list of the lines in S, breaking at line boundaries. |      Line breaks are not included in the resulting list unless keepends |      is given and true. |   |  startswith(...) |      S.startswith(prefix[, start[, end]]) -> bool |       |      Return True if S starts with the specified prefix, False otherwise. |      With optional start, test S beginning at that position. |      With optional end, stop comparing S at that position. |      prefix can also be a tuple of strings to try.>>> str1.startswith("a")True>>> |   |  strip(...) |      S.strip([chars]) -> string or unicode |       |      Return a copy of the string S with leading and trailing |      whitespace removed. |      If chars is given and not None, remove characters in chars instead. |      If chars is unicode, S will be converted to unicode before stripping>>> str1 = "     Helo,wollll    ">>> str1.strip()'Helo,wollll'>>>  |   |  swapcase(...) |      S.swapcase() -> string |       |      Return a copy of the string S with uppercase characters |      converted to lowercase and vice versa.>>> str1 = "     Helo,wollll    ">>> str1.strip()'Helo,wollll'>>> >>> >>> str1.swapcase()'     hELO,WOLLLL    '>>> |  |  title(...) |      S.title() -> string |       |      Return a titlecased version of S, i.e. words start with uppercase |      characters, all remaining cased characters have lowercase.a = "hello,world">>> a.title()'Hello,World'>>>  |   |  translate(...) |      S.translate(table [,deletechars]) -> string |       |      Return a copy of the string S, where all characters occurring |      in the optional argument deletechars are removed, and the |      remaining characters have been mapped through the given |      translation table, which must be a string of length 256 or None. |      If the table argument is None, no translation is applied and |      the operation simply removes the characters in deletechars. |   |  upper(...) |      S.upper() -> string |       |      Return a copy of the string S converted to uppercase.>>> str1.swapcase()'     hELO,WOLLLL    '>>> a = "hello,world">>> a.title()'Hello,World'>>> a.upper()'HELLO,WORLD'>>>  |   |  zfill(...) |      S.zfill(width) -> string |       |      Pad a numeric string S with zeros on the left, to fill a field |      of the specified width.  The string S is never truncated. |   |  ---------------------------------------------------------------------- |  Data and other attributes defined here: |   |  __new__ = <built-in method __new__ of type object> |      T.__new__(S, ...) -> a new object with type S, a subtype of T