python開發基礎01-字符串操做方法彙總

字符串

　　Python對字符串的處理內置了不少高效的函數，很是方便功能很強大。

"hello world"

字符串七種經常使用功能：

• 鏈接和合並 + join
• 移除空白  strip
• 分割 split
• 長度 len()
• 索引 str[index]
• 切片 str[0,7]
• 替換 replace()

1.1 字符串的鏈接和合並

鏈接和合並

相加 //兩個字符串能夠很方便的經過'+'鏈接起來

合併//用join方法

text1="David"
text2="J"
v=text1+text2
print(v)
v1="_".join(v)
print(v1)
# DavidJ
# D_a_v_i_d_J

　

1.2 字符串的索引、切片

索引

切片

text="David J"
# v1=text[0]
# v1=text[0:1] #0=<  <1
# v1=text[0:-1]
# v1=text[0:len(text)+1]
v1=text[1:]
print(v1)

　　

1.3 字符串的分割

普通的分割，用split

split只能作很是簡單的分割，並且不支持多個分隔

text = '1+2+4'

v1,v2,v3=text.split(+)

複雜的分割

r表示不轉義,分隔符能夠是;或者,或者空格後面跟0個多個額外的空格，而後按照這個模式去分割

# 分割
phone='400-800-800-1234'
print(phone.split('-'))
##['400', '800', '800', '1234']
#複雜分割 import re
import re
text="hello world; python,David J like it!"
v=re.split(r'[;,!s]\s*',text)
print(v)
##['hello world', 'python', 'David J like it', '']

 

1.4 字符串的查找和匹配

通常查找 find

咱們能夠很方便的在長的字符串裏面查找子字符串，會返回子字符串所在位置的索引, 若找不到返回-1

 複雜的匹配可參考re.match

#字符串的查找和匹配
text="布爾值分別有什麼?"
v1=text.find("布爾")
v2=text.find("爾")
v3=text.find("爾",3)
v4=text.find("bool")
print(v1,v2,v3,v4)
##0 1 -1 -1
#複雜的匹配可參考使用re.match

　　

 

1.5 字符串的替換

普通的替換,用replace就能夠

若要處理複雜的或者多個的替換，須要用到re模塊的sub函數

#字符串的替換
text="David J like zhuzhu"
v1=text.replace("vid","wei")
print(v1)
import re
text2="Shandong 37,Shanxi 14"
v2=re.sub(r'\d+','100',text2)
print(v2)
# Dawei J like zhuzhu
# Shandong 100,Shanxi 100

　　

 

1.6 字符串中去掉一些字符

去除空格：對文本處理的時候好比從文件中讀取一行或獲取用戶名輸入後，去除字符串首尾的空格，table /t或者是換行符/n

text="\t hello everyone,\t i am David J.\n"
print(text)
v1=text.strip()
v2=text.rstrip()
v3=text.lstrip()
v4=text.strip("\t")
print(v1)
print(v2)
print(v3)
print(v4)

複雜的文本清理,能夠利用str.translate

字符串遍歷

for 變量名 in 字符串：

　變量名

 兩種遍歷

for i in range(0,100,1):

for i in range(100,0,-1):

　　print(i)

字符串特性注意

字符串一旦建立，不能修改

一旦修改或拼接，都會從新生成新字符串

 

 

 

字符串各方法源碼及註釋：

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.
    """
    def capitalize(self):  
        """ 首字母變大寫 """
        """
        S.capitalize() -> string
        
        Return a copy of the string S with only its first character
        capitalized.
        """
        return ""

    def center(self, width, fillchar=None):  
        """ 內容居中，width：總長度；fillchar：空白處填充內容，默認無 """
        """
        S.center(width[, fillchar]) -> string
        
        Return S centered in a string of length width. Padding is
        done using the specified fill character (default is a space)
        """
        return ""

    def count(self, sub, start=None, end=None):  
        """ 子序列個數 """
        """
        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.
        """
        return 0

    def decode(self, encoding=None, errors=None):  
        """ 解碼 """
        """
        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.
        """
        return object()

    def encode(self, encoding=None, errors=None):  
        """ 編碼，針對unicode """
        """
        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.
        """
        return object()

    def endswith(self, suffix, start=None, end=None):  
        """ 是否以 xxx 結束 """
        """
        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.
        """
        return False

    def expandtabs(self, tabsize=None):  
        """ 將tab轉換成空格，默認一個tab轉換成8個空格 """
        """
        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.
        """
        return ""

    def find(self, sub, start=None, end=None):  
        """ 尋找子序列位置，若是沒找到，返回 -1 """
        """
        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.
        """
        return 0

    def format(*args, **kwargs): # known special case of str.format
        """ 字符串格式化，動態參數，將函數式編程時細說 """
        """
        S.format(*args, **kwargs) -> string
        
        Return a formatted version of S, using substitutions from args and kwargs.
        The substitutions are identified by braces ('{' and '}').
        """
        pass

    def index(self, sub, start=None, end=None):  
        """ 子序列位置，若是沒找到，報錯 """
        S.index(sub [,start [,end]]) -> int
        
        Like S.find() but raise ValueError when the substring is not found.
        """
        return 0

    def isalnum(self):  
        """ 是不是字母和數字 """
        """
        S.isalnum() -> bool
        
        Return True if all characters in S are alphanumeric
        and there is at least one character in S, False otherwise.
        """
        return False

    def isalpha(self):  
        """ 是不是字母 """
        """
        S.isalpha() -> bool
        
        Return True if all characters in S are alphabetic
        and there is at least one character in S, False otherwise.
        """
        return False

    def isdigit(self):  
        """ 是不是數字 """
        """
        S.isdigit() -> bool
        
        Return True if all characters in S are digits
        and there is at least one character in S, False otherwise.
        """
        return False

    def islower(self):  
        """ 是否小寫 """
        """
        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.
        """
        return False

    def isspace(self):  
        """
        S.isspace() -> bool
        
        Return True if all characters in S are whitespace
        and there is at least one character in S, False otherwise.
        """
        return False

    def istitle(self):  
        """
        S.istitle() -> bool
        
        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.
        """
        return False

    def isupper(self):  
        """
        S.isupper() -> bool
        
        Return True if all cased characters in S are uppercase and there is
        at least one cased character in S, False otherwise.
        """
        return False

    def join(self, iterable):  
        """ 鏈接 """
        """
        S.join(iterable) -> string
        
        Return a string which is the concatenation of the strings in the
        iterable.  The separator between elements is S.
        """
        return ""

    def ljust(self, width, fillchar=None):  
        """ 內容左對齊，右側填充 """
        """
        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).
        """
        return ""

    def lower(self):  
        """ 變小寫 """
        """
        S.lower() -> string
        
        Return a copy of the string S converted to lowercase.
        """
        return ""

    def lstrip(self, chars=None):  
        """ 移除左側空白 """
        """
        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 stripping
        """
        return ""

    def partition(self, sep):  
        """ 分割，前，中，後三部分 """
        """
        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.
        """
        pass

    def replace(self, old, new, count=None):  
        """ 替換 """
        """
        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.
        """
        return ""

    def rfind(self, sub, start=None, end=None):  
        """
        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.
        """
        return 0

    def rindex(self, sub, start=None, end=None):  
        """
        S.rindex(sub [,start [,end]]) -> int
        
        Like S.rfind() but raise ValueError when the substring is not found.
        """
        return 0

    def rjust(self, width, fillchar=None):  
        """
        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)
        """
        return ""

    def rpartition(self, sep):  
        """
        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.
        """
        pass

    def rsplit(self, sep=None, maxsplit=None):  
        """
        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.
        """
        return []

    def rstrip(self, chars=None):  
        """
        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
        """
        return ""

    def split(self, sep=None, maxsplit=None):  
        """ 分割， maxsplit最多分割幾回 """
        """
        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.
        """
        return []

    def splitlines(self, keepends=False):  
        """ 根據換行分割 """
        """
        S.splitlines(keepends=False) -> 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.
        """
        return []

    def startswith(self, prefix, start=None, end=None):  
        """ 是否起始 """
        """
        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.
        """
        return False

    def strip(self, chars=None):  
        """ 移除兩段空白 """
        """
        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
        """
        return ""

    def swapcase(self):  
        """ 大寫變小寫，小寫變大寫 """
        """
        S.swapcase() -> string
        
        Return a copy of the string S with uppercase characters
        converted to lowercase and vice versa.
        """
        return ""

    def title(self):  
        """
        S.title() -> string
        
        Return a titlecased version of S, i.e. words start with uppercase
        characters, all remaining cased characters have lowercase.
        """
        return ""

    def translate(self, table, deletechars=None):  
        """
        轉換，須要先作一個對應表，最後一個表示刪除字符集合
        intab = "aeiou"
        outtab = "12345"
        trantab = maketrans(intab, outtab)
        str = "this is string example....wow!!!"
        print str.translate(trantab, 'xm')
        """

        """
        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.
        """
        return ""

    def upper(self):  
        """
        S.upper() -> string
        
        Return a copy of the string S converted to uppercase.
        """
        return ""

    def zfill(self, width):  
        """方法返回指定長度的字符串，原字符串右對齊，前面填充0。"""
        """
        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.
        """
        return ""

    def _formatter_field_name_split(self, *args, **kwargs): # real signature unknown
        pass

    def _formatter_parser(self, *args, **kwargs): # real signature unknown
        pass

    def __add__(self, y):  
        """ x.__add__(y) <==> x+y """
        pass

    def __contains__(self, y):  
        """ x.__contains__(y) <==> y in x """
        pass

    def __eq__(self, y):  
        """ x.__eq__(y) <==> x==y """
        pass

    def __format__(self, format_spec):  
        """
        S.__format__(format_spec) -> string
        
        Return a formatted version of S as described by format_spec.
        """
        return ""

    def __getattribute__(self, name):  
        """ x.__getattribute__('name') <==> x.name """
        pass

    def __getitem__(self, y):  
        """ x.__getitem__(y) <==> x[y] """
        pass

    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        pass

    def __getslice__(self, i, j):  
        """
        x.__getslice__(i, j) <==> x[i:j]
                   
                   Use of negative indices is not supported.
        """
        pass

    def __ge__(self, y):  
        """ x.__ge__(y) <==> x>=y """
        pass

    def __gt__(self, y):  
        """ x.__gt__(y) <==> x>y """
        pass

    def __hash__(self):  
        """ x.__hash__() <==> hash(x) """
        pass

    def __init__(self, string=''): # known special case of str.__init__
        """
        str(object='') -> string
        
        Return a nice string representation of the object.
        If the argument is a string, the return value is the same object.
        # (copied from class doc)
        """
        pass

    def __len__(self):  
        """ x.__len__() <==> len(x) """
        pass

    def __le__(self, y):  
        """ x.__le__(y) <==> x<=y """
        pass

    def __lt__(self, y):  
        """ x.__lt__(y) <==> x<y """
        pass

    def __mod__(self, y):  
        """ x.__mod__(y) <==> x%y """
        pass

    def __mul__(self, n):  
        """ x.__mul__(n) <==> x*n """
        pass

    @staticmethod # known case of __new__
    def __new__(S, *more):  
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass

    def __ne__(self, y):  
        """ x.__ne__(y) <==> x!=y """
        pass

    def __repr__(self):  
        """ x.__repr__() <==> repr(x) """
        pass

    def __rmod__(self, y):  
        """ x.__rmod__(y) <==> y%x """
        pass

    def __rmul__(self, n):  
        """ x.__rmul__(n) <==> n*x """
        pass

    def __sizeof__(self):  
        """ S.__sizeof__() -> size of S in memory, in bytes """
        pass

    def __str__(self):  
        """ x.__str__() <==> str(x) """
        pass

str