第十三節，基本數據類型，數字int字符串str

 

基本數據類型

　　數字　　　　　int

　　字符串　　　　str

　　布爾值　　　　bool

　　列表　　　　　list

　　元組　　　　　tuple

　　字典　　　　　dict

 

數據類型關係圖

　　

 

 

查看一個對象的類

　　如：如查看對象變量a是什麼類          用到函數type(),函數值是要查看的對象變量

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = type(a)
5 print(b)

　　如上就會輸出：<type 'str'>    str是字符串類

 

　　查看一個對象類的類庫

　　如上列，查到對象的類後，將類名稱寫在下面，按着ctrl鍵用鼠標點擊這個類名稱，就能夠進入這個類的類庫

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = type(a)
5 print(b)
6 str      #按着ctrl鍵用鼠標點擊這個類名稱，就能夠進入這個類的類庫

 

每個類的類庫裏都有操做對象的各類功能

　　如：將小寫字母轉換大寫字母

　　調用功能書寫格式：（對象變量.功能函數)

1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = "nih" 4 b = a.upper() 5 print(b)

　 如上列a爲字符串類的對象變量，upper()爲字符串類的類庫功能函數，b=a.upper() 打印b就將字符串轉換成大寫的了，輸出NIH

 

查看一個對象功能函數

　　如：上列　

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = a.upper()  #按着ctrl鍵用鼠標點擊這個對象功能函數，就能夠進入這個類的類庫，找到對應的函數源碼
5 print(b)

　　按着ctrl鍵用鼠標點擊這個對象功能函數，就能夠進入這個類的類庫，找到對應的函數源碼

 

查看一個對象的類庫裏具有哪些功能

　　如：

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = dir(a)  
5 print(b)
6 #運行後打印出對象類庫的全部具有功能

　　這樣就會獲得：['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__',等等

 

查看一個對象類庫的全部功能與詳情使用方法等

　　如：

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = help(type(a))
5 print(b)
6 #運行後打印出對象類庫的全部具有功能

 

基本數據，對象類庫裏的經常使用功能

　　注意:對象類庫裏的功能函數，先後帶有下劃線的爲特殊函數，是python程序的內置函數

　　如： __add__

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 a = 123
 4 b = 456
 5 print(a + b)
 6 #如上列，其實內部計算流程是
 7 a = 123
 8 b = 456
 9 print(a.__add__(b))
10 #因此兩個結果是同樣的

　　因此目前能夠不用管它

 

 

打印出對象在內存的地址

 

    id()

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = 123
4 b = id(a)
5 print(b)
6 #打印出對象在內存的地址 1422458480

 

 

 

　　1.整數，int

　　　　

　　　　建立整數對象

 

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = 123
4 print(a)
5 #或者
6 b = int(123)
7 print(b)　　

　　

特別說明：全部以類名稱加（）建立的一個類對象都是執行的類庫裏的（__init__ ）這個功能,初始化的意思

如：

int(123)   執行的對應功能是 __init__

然而 a = 123   又是轉換成  a = int(123)    最後仍是執行的__init__ 這個功能

其餘類也是如此，每個類都有__init__ 初始化

　　

 

　　　　__add__()　　　　相加　　　　格式：a.__add__(b)

　　　　bit_length()　　　取二進制的最小表示位數（返回多少位）　　　　格式：a.bit_length()

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = 4
4 b = a.bit_length()
5 print(b)

　

class int(object):
    """
    int(x=0) -> int or long
    int(x, base=10) -> int or long
    
    Convert a number or string to an integer, or return 0 if no arguments
    are given.  If x is floating point, the conversion truncates towards zero.
    If x is outside the integer range, the function returns a long instead.
    
    If x is not a number or if base is given, then x must be a string or
    Unicode object representing an integer literal in the given base.  The
    literal can be preceded by '+' or '-' and be surrounded by whitespace.
    The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
    interpret the base from the string as an integer literal.
    >>> int('0b100', base=0)
    4
    """
    def bit_length(self): 
        """ 返回表示該數字的時佔用的最少位數 """
        """
        int.bit_length() -> int
        
        Number of bits necessary to represent self in binary.
        >>> bin(37)
        '0b100101'
        >>> (37).bit_length()
        6
        """
        return 0

    def conjugate(self, *args, **kwargs): # real signature unknown
        """ 返回該複數的共軛複數 """
        """ Returns self, the complex conjugate of any int. """
        pass

    def __abs__(self):
        """ 返回絕對值 """
        """ x.__abs__() <==> abs(x) """
        pass

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

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

    def __cmp__(self, y): 
        """ 比較兩個數大小 """
        """ x.__cmp__(y) <==> cmp(x,y) """
        pass

    def __coerce__(self, y):
        """ 強制生成一個元組 """ 
        """ x.__coerce__(y) <==> coerce(x, y) """
        pass

    def __divmod__(self, y): 
        """ 相除，獲得商和餘數組成的元組 """ 
        """ x.__divmod__(y) <==> divmod(x, y) """
        pass

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

    def __float__(self): 
        """ 轉換爲浮點類型 """ 
        """ x.__float__() <==> float(x) """
        pass

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

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

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

    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        """ 內部調用 __new__方法或建立對象時傳入參數使用 """ 
        pass

    def __hash__(self): 
        """若是對象object爲哈希表類型，返回對象object的哈希值。哈希值爲整數。在字典查找中，哈希值用於快速比較字典的鍵。兩個數值若是相等，則哈希值也相等。"""
        """ x.__hash__() <==> hash(x) """
        pass

    def __hex__(self): 
        """ 返回當前數的 十六進制 表示 """ 
        """ x.__hex__() <==> hex(x) """
        pass

    def __index__(self): 
        """ 用於切片，數字無心義 """
        """ x[y:z] <==> x[y.__index__():z.__index__()] """
        pass

    def __init__(self, x, base=10): # known special case of int.__init__
        """ 構造方法，執行 x = 123 或 x = int(10) 時，自動調用，暫時忽略 """ 
        """
        int(x=0) -> int or long
        int(x, base=10) -> int or long
        
        Convert a number or string to an integer, or return 0 if no arguments
        are given.  If x is floating point, the conversion truncates towards zero.
        If x is outside the integer range, the function returns a long instead.
        
        If x is not a number or if base is given, then x must be a string or
        Unicode object representing an integer literal in the given base.  The
        literal can be preceded by '+' or '-' and be surrounded by whitespace.
        The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
        interpret the base from the string as an integer literal.
        >>> int('0b100', base=0)
        4
        # (copied from class doc)
        """
        pass

    def __int__(self): 
        """ 轉換爲整數 """ 
        """ x.__int__() <==> int(x) """
        pass

    def __invert__(self): 
        """ x.__invert__() <==> ~x """
        pass

    def __long__(self): 
        """ 轉換爲長整數 """ 
        """ x.__long__() <==> long(x) """
        pass

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

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

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

    def __neg__(self): 
        """ x.__neg__() <==> -x """
        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 __nonzero__(self): 
        """ x.__nonzero__() <==> x != 0 """
        pass

    def __oct__(self): 
        """ 返回改值的 八進制 表示 """ 
        """ x.__oct__() <==> oct(x) """
        pass

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

    def __pos__(self): 
        """ x.__pos__() <==> +x """
        pass

    def __pow__(self, y, z=None): 
        """ 冪，次方 """ 
        """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """
        pass

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

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

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

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

    def __repr__(self): 
        """轉化爲解釋器可讀取的形式 """
        """ x.__repr__() <==> repr(x) """
        pass

    def __str__(self): 
        """轉換爲人閱讀的形式，若是沒有適於人閱讀的解釋形式的話，則返回解釋器課閱讀的形式"""
        """ x.__str__() <==> str(x) """
        pass

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

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

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

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

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

    def __rpow__(self, x, z=None): 
        """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """
        pass

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

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

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

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

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

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

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

    def __trunc__(self, *args, **kwargs): 
        """ 返回數值被截取爲整形的值，在整形中無心義 """
        pass

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

    denominator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 分母 = 1 """
    """the denominator of a rational number in lowest terms"""

    imag = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 虛數，無心義 """
    """the imaginary part of a complex number"""

    numerator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 分子 = 數字大小 """
    """the numerator of a rational number in lowest terms"""

    real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 實屬，無心義 """
    """the real part of a complex number"""

int

 

　2.字符串，str

　　　　字符串經常使用功能：
　　　　移除空白
　　　　分割
　　　　長度
　　　　索引  ：注意2.7版本索引中文字符串會亂碼，3.0版本以上沒問題
　　　　切片

 

　　建立字符串

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "你好"
4 print(a)
5 #或者
6 b = str("你好")
7 print(b)

 

 

　　　　capitalize()　　　　首字母大寫　　　　格式：a.capitalize()

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "linguixiu"
4 b = a.capitalize()
5 print(b)
6 #打印出首字母大寫  Linguixiu

　　　　center(self, width, fillchar=None) 有參

　　　　""" （內容居中），width：總長度；fillchar：空白處填充內容，默認無 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林貴秀"
4 b = a.center(20,"*")
5 print(b)
6 #打印出    *****林貴秀******

　　　　count(self, sub, start=None, end=None) 有參

　　　　""" （查找字符在字符串屬性次數），要查找的字符，查找範圍開始位置，查找範圍結束位置 """    （也就是查找一個或者多個字符，在一個字符串的出現次數）

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林貴秀去桂林桂林山水秀天下"
4 b = a.count("林", 0, 18)
5 print(b)
6 #打印出林字在字符串出現的次數 2

　　　　注意一箇中文字符，算3個字符，空格也算一個字符

 

　　　　endswith(self, suffix, start=None, end=None): 有參

　　　　返回：真或者假

　　　　""" （是否以 xxx 結束），要判斷的字符，判斷範圍開始位置，判斷範圍結束位置 """

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 a = "nihzhongguo"
 4 b = a.endswith("o")
 5 print(b)
 6 #判斷字符串是不是o結尾打印出True
 7 
 8 a = "nihzhongguo"
 9 b = a.endswith("o", 0, 5)
10 print(b)
11 #判斷字符串從0到第5個位置是不是以o結尾 打印出False

　　　　

　　　　expandtabs(self, tabsize=None)有參

　　　　""" （將tab轉換成空格，默認一個tab轉換成8個空格），自定義換成空格數 """

　　　　注意：\t表示tab鍵，若是在編輯器直接tab鍵，編輯器會自動轉換成空格

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nihzh\tongguo"
4 b = a.expandtabs(16)
5 print(b)
6 #將tab鍵轉換成16個空格打印出 nihzh           ongguo
7 #注意若是不指定，默認是8個

　　　　find(self, sub, start=None, end=None)　　有參

　　　　""" (尋找字符在字符串裏的位置)，要查找的字符，查找字符串起始位置，查找字符串結束位置，若是找到返回位置數，若是沒找到，返回 -1 """　　 

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nihzhongguo"
4 b = a.find("o")
5 print(b)
6 #打印輸出o在字符串裏的位置 5
7 #若是沒找到輸出的是 -1

　　　　format(*args, **kwargs)有參

 　　　 """ （替換字符串裏的佔位符），動態參數，將函數式編程時細說 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "姓名 {0} 年齡 {1}"
4 #{}站位符裏面通常從0編號
5 b = a.format("林貴秀", "30")
6 print(b)
7 #替換字符串裏的佔位符 輸出 姓名 林貴秀 年齡 30

　　　isalnum(self)　

　　　""" （判斷字符串是不是純字母和數字） 是純字母或數字返回真，不然返回假"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林貴秀123aaa"
4 b = a.isalnum()
5 print(b)
6 #輸出 False 表示不是純字母或數字

　　isalpha(self)　　

　　""" （是不是純字母）是字母返回真，不然返回假 """　

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "hsdfujhrt"
4 b = a.isalpha()
5 print(b)
6 #輸出 True 表示是純字母

　　isdigit(self)

　　 """ （是不是純數字）是純數字返回真，不然返回假 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "123456"
4 b = a.isdigit()
5 print(b)
6 #輸出 True 表示是純數字

　　islower(self)

　　""" （字符串裏的字母是不是純小寫）是返回真，不然返回假 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林貴秀asdd12434346"
4 b = a.islower()
5 print(b)
6 #輸出 True 表示是純小寫

　　isspace(self)

　　"""(判斷字符串是不是純空格)是返回真，不然返回假"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "  "
4 b = a.isspace()
5 print(b)
6 #輸出 True 表示是純空格

　　istitle(self)　

　　"""(判斷英文首字母是否大寫)是返回真，不然返回假"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "Nihao"
4 b = a.istitle()
5 print(b)
6 #輸出 True 表示首字母是大寫

 　　isupper(self)

　　"""(判斷是否所有字母是大寫)是返回真，不然返回假"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "NGGGEAWG"
4 b = a.isupper()
5 print(b)
6 #輸出 True 表示字母所有是大寫

　　join(self, iterable)有參

　　""" （鏈接一個列表成一串字符串）"連接符".join(字符串變量)"""

　　注意：若是連接符 " " 爲空，連接起來就是一串沒有連接符的字符串

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = ["李彥宏" , "馬雲" , "周鴻禕"]
4 b = "|".join(a)
5 print(b)
6 #輸出 李彥宏|馬雲|周鴻禕  將列表連接成一串字符串

　　ljust(self, width, fillchar=None)

　　""" （內容左對齊，右側填充）寬度，填充符 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "李彥宏"
4 b = a.ljust(20,"#")
5 print(b)
6 #輸出 李彥宏###########  

　　lower(self)

　　""" （字符串變小寫 ）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "FDHDFrherheh"
4 b = a.lower()
5 print(b)
6 #輸出字符串變小寫 fdhdfrherheh

　　lstrip(self, chars=None)

　　 """ （移除左側空白 ）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "  林貴秀  "
4 b = a.lstrip()
5 print(b)
6 #輸出 林貴秀  去除左邊空格

　　

　　rstrip(self, chars=None)

　　 """ （移除右側空白 ）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "  林貴秀  "
4 b = a.rstrip()
5 print(b)
6 #輸出   林貴秀 去除右邊空格

　　strip(self, chars=None)

　　 """ （移除兩邊空白 ）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "  林貴秀  "
4 b = a.strip()
5 print(b)
6 #輸出 林貴秀 去除兩邊空格

 

　　partition(self, sep)有參

　　 """ （分割，前，中，後三部分）分割位置字符 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "abcdefjhi"
4 b = a.partition("def")
5 print(b)
6 #輸出 ('abc', 'def', 'jhi') 從位置字符那裏分割，返回元組

　　replace(self, old, new, count=None)

　　"""（ 替換）字符串裏被替換的字符，替換成什麼字符，可選：位置從左向右找幾個 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林貴秀30歲了"
4 b = a.replace("30", "20")
5 print(b)
6 #輸出 林貴秀20歲了 將字符串裏的字符替換成指定字符

 　　split(self, sep=None, maxsplit=None)

　　 """ （分割字符串），要分割的標示字符，標示字符分割有效位置：也就是從左邊開始最多分割幾回 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "fawweffefwefelfqf"
4 b = a.split("e",2)
5 print(b)
6 #輸出 ['faww', 'ff', 'fwefelfqf'] 返回分割後的列表

　　splitlines(self, keepends=False)

　　""" （根據換行分割） """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "fawweffe\nfwefelfqf"
4 b = a.splitlines()
5 print(b)
6 #輸出 ['fawweffe', 'fwefelfqf'] 返回分割後的列表

　　startswith(self, prefix, start=None, end=None)

　　""" （判斷是否以某一個字符或者字符串起始）要判斷的字符或字符串：返回真或者假 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "中國的城市有北京"
4 b = a.startswith("中國")
5 print(b)
6 #輸出 True 返回真

 　　swapcase(self)

　　""" （大寫變小寫，小寫變大寫 ）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "abcdABCD"
4 b = a.swapcase()
5 print(b)
6 #輸出 ABCDabcd 返回大寫變小寫，小寫變大寫

　　索引　

　　索引：把一串字符串分紅每一個字符爲一個新字符串

索引  ：注意2.7版本索引中文字符串會亂碼，3.0版本以上沒問題 (2.7是以字節編碼的，3.0是以字符編碼的)

說明：2.7版本中文是以字節編碼的，如utf-8 一箇中文是3個字節，因此當索引字符下標是一個漢字是有3個下標的，索引一個下標不是一個完整的漢字，就會出現亂碼

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "你好"
4 print(a[0])#索引一個下標不是一個完整的漢字，就會出現亂碼

2.7版本中，用切片的方法打印一個漢字

說明：切片能夠指定字符下標範圍，如utf-8 一箇中文是3個字節，若是0到3的範圍，恰好是一個字

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "你好"
4 print(a[0:3])#用切片的方式0到3，就能打印出（你）字，由於utf-8字符編碼一個漢字3個字節

 

　　判斷索引數用 len() 函數  通常配合循環使用

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 #索引：把一串字符串分紅每一個字符爲一個新字符串
 4 #以字符下標位置分開
 5 a = "adce"
 6 print(a[0])
 7 print(a[1])
 8 print(a[2])
 9 print(a[3])
10 #如上打印出：a、d、c、e 四個獨立的新字符串
11 
12 #判斷一個字符串有多少個下標字符以下
13 a = "adce"
14 b = len(a)
15 print(b)
16 #輸出 4 也就是說這個字符串有4個下標字符

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 #索引：結合循環應用
 4 #while循環
 5 b = 0
 6 a = "hfewfhopghg0u9o0gh0ghgygh0329gh0392gh0239g2g"
 7 while b < len(a):
 8     print(a[b])
 9     b += 1
10 else:
11     pass
12 #循環出索引

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 #索引：結合循環應用
4 # #for循環
5 #b爲循環自定義變量
6 a = "hfewfhopghg0u9o0gh0ghgygh0329gh0392gh0239g2g"
7 for b in a:
8     print(b)
9 #循環出索引

 

 

　　切片　　

　　切片：把一串字符串分紅每幾個字符或者多個字符，爲一個新字符串
　　以字一個字符的下標開始，和一個字符的下標結束，切成一串新的字符串　

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 #切片：把一串字符串分紅每幾個字符或者多個字符，爲一個新字符串
4 #以字一個字符的下標開始，和一個字符的下標結束，切成一串新的字符串
5 a = "adcefhwieufgweufhggh"
6 print(a[0:4])
7 print(a[4:10])
8 print(a[10:20])
9 #如上打印出：adce、fhwieu、fgweufhggh 切成四個獨立的新字符串

 

bytes字節類型 3.5版本有效

"""(將字符串轉換成16進制，要轉換的字符串變量,encoding='字符編碼')"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 #bytes類,將字符串轉換成16進製表示
4 #將字符串轉換成16進製表示
5 a = "林貴秀"
6 a1 = bytes(a,encoding='utf-8')
7 print(a1)
8 a2 = bytes(a,encoding='gbk')
9 print(a2)

str 字符串類型，將字節表示的16進制轉換成字符串

"""(16進制字節轉換成字符串，16進制變量,encoding='字符編碼')"""

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 #str將16進制轉換成字符串
 4 b = "林貴秀"
 5 b1 = bytes(b,encoding='utf-8')
 6 c1 = str(b1,encoding='utf-8')
 7 print(c1)
 8 
 9 b2 = bytes(b,encoding='gbk')
10 c2 = str(b2,encoding='gbk')
11 print(c2)

 

將字符串，轉換成16進制，10進制，二進制   

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 #bytes類,將字符串轉換成16進製表示
 4 a = "李露"
 5 print(a)#字符串表示
 6 #輸出 李露
 7 
 8 #用bytes類，將字符串轉換成16進制
 9 print(bytes(a,encoding='utf-8'))#將字符串轉換成16進製表示
10 #輸出 b'\xe4\xbd\xa0\xe5\xa5\xbd'  16進製表示的二進制
11 
12 #用for將16進制循環出10進制
13 b = bytes(a,encoding='utf-8')#將16進制轉換成10進制
14 for i in b:#for循環16進制的時候默認會以10進制方式循環出數據
15     print(i)
16 #輸出
17 # 230
18 # 157
19 # 142
20 # 233
21 # 156
22 # 178
23 
24 #用bin將10進制轉換成二進制
25 c = bytes(a,encoding='utf-8')
26 for i in c:
27     print(i,bin(i))
28 #輸出
29 # 230 0b11100110
30 # 157 0b10011101
31 # 142 0b10001110
32 # 233 0b11101001
33 # 156 0b10011100
34 # 178 0b10110010

 

  1 class str(basestring):
  2     """
  3     str(object='') -> string
  4     
  5     Return a nice string representation of the object.
  6     If the argument is a string, the return value is the same object.
  7     """
  8     def capitalize(self):  
  9         """ 首字母變大寫 """
 10         """
 11         S.capitalize() -> string
 12         
 13         Return a copy of the string S with only its first character
 14         capitalized.
 15         """
 16         return ""
 17 
 18     def center(self, width, fillchar=None):  
 19         """ 內容居中，width：總長度；fillchar：空白處填充內容，默認無 """
 20         """
 21         S.center(width[, fillchar]) -> string
 22         
 23         Return S centered in a string of length width. Padding is
 24         done using the specified fill character (default is a space)
 25         """
 26         return ""
 27 
 28     def count(self, sub, start=None, end=None):  
 29         """ 子序列個數 """
 30         """
 31         S.count(sub[, start[, end]]) -> int
 32         
 33         Return the number of non-overlapping occurrences of substring sub in
 34         string S[start:end].  Optional arguments start and end are interpreted
 35         as in slice notation.
 36         """
 37         return 0
 38 
 39     def decode(self, encoding=None, errors=None):  
 40         """ 解碼 """
 41         """
 42         S.decode([encoding[,errors]]) -> object
 43         
 44         Decodes S using the codec registered for encoding. encoding defaults
 45         to the default encoding. errors may be given to set a different error
 46         handling scheme. Default is 'strict' meaning that encoding errors raise
 47         a UnicodeDecodeError. Other possible values are 'ignore' and 'replace'
 48         as well as any other name registered with codecs.register_error that is
 49         able to handle UnicodeDecodeErrors.
 50         """
 51         return object()
 52 
 53     def encode(self, encoding=None, errors=None):  
 54         """ 編碼，針對unicode """
 55         """
 56         S.encode([encoding[,errors]]) -> object
 57         
 58         Encodes S using the codec registered for encoding. encoding defaults
 59         to the default encoding. errors may be given to set a different error
 60         handling scheme. Default is 'strict' meaning that encoding errors raise
 61         a UnicodeEncodeError. Other possible values are 'ignore', 'replace' and
 62         'xmlcharrefreplace' as well as any other name registered with
 63         codecs.register_error that is able to handle UnicodeEncodeErrors.
 64         """
 65         return object()
 66 
 67     def endswith(self, suffix, start=None, end=None):  
 68         """ 是否以 xxx 結束 """
 69         """
 70         S.endswith(suffix[, start[, end]]) -> bool
 71         
 72         Return True if S ends with the specified suffix, False otherwise.
 73         With optional start, test S beginning at that position.
 74         With optional end, stop comparing S at that position.
 75         suffix can also be a tuple of strings to try.
 76         """
 77         return False
 78 
 79     def expandtabs(self, tabsize=None):  
 80         """ 將tab轉換成空格，默認一個tab轉換成8個空格 """
 81         """
 82         S.expandtabs([tabsize]) -> string
 83         
 84         Return a copy of S where all tab characters are expanded using spaces.
 85         If tabsize is not given, a tab size of 8 characters is assumed.
 86         """
 87         return ""
 88 
 89     def find(self, sub, start=None, end=None):  
 90         """ 尋找子序列位置，若是沒找到，返回 -1 """
 91         """
 92         S.find(sub [,start [,end]]) -> int
 93         
 94         Return the lowest index in S where substring sub is found,
 95         such that sub is contained within S[start:end].  Optional
 96         arguments start and end are interpreted as in slice notation.
 97         
 98         Return -1 on failure.
 99         """
100         return 0
101 
102     def format(*args, **kwargs): # known special case of str.format
103         """ 字符串格式化，動態參數，將函數式編程時細說 """
104         """
105         S.format(*args, **kwargs) -> string
106         
107         Return a formatted version of S, using substitutions from args and kwargs.
108         The substitutions are identified by braces ('{' and '}').
109         """
110         pass
111 
112     def index(self, sub, start=None, end=None):  
113         """ 子序列位置，若是沒找到，報錯 """
114         S.index(sub [,start [,end]]) -> int
115         
116         Like S.find() but raise ValueError when the substring is not found.
117         """
118         return 0
119 
120     def isalnum(self):  
121         """ 是不是字母和數字 """
122         """
123         S.isalnum() -> bool
124         
125         Return True if all characters in S are alphanumeric
126         and there is at least one character in S, False otherwise.
127         """
128         return False
129 
130     def isalpha(self):  
131         """ 是不是字母 """
132         """
133         S.isalpha() -> bool
134         
135         Return True if all characters in S are alphabetic
136         and there is at least one character in S, False otherwise.
137         """
138         return False
139 
140     def isdigit(self):  
141         """ 是不是數字 """
142         """
143         S.isdigit() -> bool
144         
145         Return True if all characters in S are digits
146         and there is at least one character in S, False otherwise.
147         """
148         return False
149 
150     def islower(self):  
151         """ 是否小寫 """
152         """
153         S.islower() -> bool
154         
155         Return True if all cased characters in S are lowercase and there is
156         at least one cased character in S, False otherwise.
157         """
158         return False
159 
160     def isspace(self):  
161         """
162         S.isspace() -> bool
163         
164         Return True if all characters in S are whitespace
165         and there is at least one character in S, False otherwise.
166         """
167         return False
168 
169     def istitle(self):  
170         """
171         S.istitle() -> bool
172         
173         Return True if S is a titlecased string and there is at least one
174         character in S, i.e. uppercase characters may only follow uncased
175         characters and lowercase characters only cased ones. Return False
176         otherwise.
177         """
178         return False
179 
180     def isupper(self):  
181         """
182         S.isupper() -> bool
183         
184         Return True if all cased characters in S are uppercase and there is
185         at least one cased character in S, False otherwise.
186         """
187         return False
188 
189     def join(self, iterable):  
190         """ 鏈接 """
191         """
192         S.join(iterable) -> string
193         
194         Return a string which is the concatenation of the strings in the
195         iterable.  The separator between elements is S.
196         """
197         return ""
198 
199     def ljust(self, width, fillchar=None):  
200         """ 內容左對齊，右側填充 """
201         """
202         S.ljust(width[, fillchar]) -> string
203         
204         Return S left-justified in a string of length width. Padding is
205         done using the specified fill character (default is a space).
206         """
207         return ""
208 
209     def lower(self):  
210         """ 變小寫 """
211         """
212         S.lower() -> string
213         
214         Return a copy of the string S converted to lowercase.
215         """
216         return ""
217 
218     def lstrip(self, chars=None):  
219         """ 移除左側空白 """
220         """
221         S.lstrip([chars]) -> string or unicode
222         
223         Return a copy of the string S with leading whitespace removed.
224         If chars is given and not None, remove characters in chars instead.
225         If chars is unicode, S will be converted to unicode before stripping
226         """
227         return ""
228 
229     def partition(self, sep):  
230         """ 分割，前，中，後三部分 """
231         """
232         S.partition(sep) -> (head, sep, tail)
233         
234         Search for the separator sep in S, and return the part before it,
235         the separator itself, and the part after it.  If the separator is not
236         found, return S and two empty strings.
237         """
238         pass
239 
240     def replace(self, old, new, count=None):  
241         """ 替換 """
242         """
243         S.replace(old, new[, count]) -> string
244         
245         Return a copy of string S with all occurrences of substring
246         old replaced by new.  If the optional argument count is
247         given, only the first count occurrences are replaced.
248         """
249         return ""
250 
251     def rfind(self, sub, start=None, end=None):  
252         """
253         S.rfind(sub [,start [,end]]) -> int
254         
255         Return the highest index in S where substring sub is found,
256         such that sub is contained within S[start:end].  Optional
257         arguments start and end are interpreted as in slice notation.
258         
259         Return -1 on failure.
260         """
261         return 0
262 
263     def rindex(self, sub, start=None, end=None):  
264         """
265         S.rindex(sub [,start [,end]]) -> int
266         
267         Like S.rfind() but raise ValueError when the substring is not found.
268         """
269         return 0
270 
271     def rjust(self, width, fillchar=None):  
272         """
273         S.rjust(width[, fillchar]) -> string
274         
275         Return S right-justified in a string of length width. Padding is
276         done using the specified fill character (default is a space)
277         """
278         return ""
279 
280     def rpartition(self, sep):  
281         """
282         S.rpartition(sep) -> (head, sep, tail)
283         
284         Search for the separator sep in S, starting at the end of S, and return
285         the part before it, the separator itself, and the part after it.  If the
286         separator is not found, return two empty strings and S.
287         """
288         pass
289 
290     def rsplit(self, sep=None, maxsplit=None):  
291         """
292         S.rsplit([sep [,maxsplit]]) -> list of strings
293         
294         Return a list of the words in the string S, using sep as the
295         delimiter string, starting at the end of the string and working
296         to the front.  If maxsplit is given, at most maxsplit splits are
297         done. If sep is not specified or is None, any whitespace string
298         is a separator.
299         """
300         return []
301 
302     def rstrip(self, chars=None):  
303         """
304         S.rstrip([chars]) -> string or unicode
305         
306         Return a copy of the string S with trailing whitespace removed.
307         If chars is given and not None, remove characters in chars instead.
308         If chars is unicode, S will be converted to unicode before stripping
309         """
310         return ""
311 
312     def split(self, sep=None, maxsplit=None):  
313         """ 分割， maxsplit最多分割幾回 """
314         """
315         S.split([sep [,maxsplit]]) -> list of strings
316         
317         Return a list of the words in the string S, using sep as the
318         delimiter string.  If maxsplit is given, at most maxsplit
319         splits are done. If sep is not specified or is None, any
320         whitespace string is a separator and empty strings are removed
321         from the result.
322         """
323         return []
324 
325     def splitlines(self, keepends=False):  
326         """ 根據換行分割 """
327         """
328         S.splitlines(keepends=False) -> list of strings
329         
330         Return a list of the lines in S, breaking at line boundaries.
331         Line breaks are not included in the resulting list unless keepends
332         is given and true.
333         """
334         return []
335 
336     def startswith(self, prefix, start=None, end=None):  
337         """ 是否起始 """
338         """
339         S.startswith(prefix[, start[, end]]) -> bool
340         
341         Return True if S starts with the specified prefix, False otherwise.
342         With optional start, test S beginning at that position.
343         With optional end, stop comparing S at that position.
344         prefix can also be a tuple of strings to try.
345         """
346         return False
347 
348     def strip(self, chars=None):  
349         """ 移除兩段空白 """
350         """
351         S.strip([chars]) -> string or unicode
352         
353         Return a copy of the string S with leading and trailing
354         whitespace removed.
355         If chars is given and not None, remove characters in chars instead.
356         If chars is unicode, S will be converted to unicode before stripping
357         """
358         return ""
359 
360     def swapcase(self):  
361         """ 大寫變小寫，小寫變大寫 """
362         """
363         S.swapcase() -> string
364         
365         Return a copy of the string S with uppercase characters
366         converted to lowercase and vice versa.
367         """
368         return ""
369 
370     def title(self):  
371         """
372         S.title() -> string
373         
374         Return a titlecased version of S, i.e. words start with uppercase
375         characters, all remaining cased characters have lowercase.
376         """
377         return ""
378 
379     def translate(self, table, deletechars=None):  
380         """
381         轉換，須要先作一個對應表，最後一個表示刪除字符集合
382         intab = "aeiou"
383         outtab = "12345"
384         trantab = maketrans(intab, outtab)
385         str = "this is string example....wow!!!"
386         print str.translate(trantab, 'xm')
387         """
388 
389         """
390         S.translate(table [,deletechars]) -> string
391         
392         Return a copy of the string S, where all characters occurring
393         in the optional argument deletechars are removed, and the
394         remaining characters have been mapped through the given
395         translation table, which must be a string of length 256 or None.
396         If the table argument is None, no translation is applied and
397         the operation simply removes the characters in deletechars.
398         """
399         return ""
400 
401     def upper(self):  
402         """
403         S.upper() -> string
404         
405         Return a copy of the string S converted to uppercase.
406         """
407         return ""
408 
409     def zfill(self, width):  
410         """方法返回指定長度的字符串，原字符串右對齊，前面填充0。"""
411         """
412         S.zfill(width) -> string
413         
414         Pad a numeric string S with zeros on the left, to fill a field
415         of the specified width.  The string S is never truncated.
416         """
417         return ""
418 
419     def _formatter_field_name_split(self, *args, **kwargs): # real signature unknown
420         pass
421 
422     def _formatter_parser(self, *args, **kwargs): # real signature unknown
423         pass
424 
425     def __add__(self, y):  
426         """ x.__add__(y) <==> x+y """
427         pass
428 
429     def __contains__(self, y):  
430         """ x.__contains__(y) <==> y in x """
431         pass
432 
433     def __eq__(self, y):  
434         """ x.__eq__(y) <==> x==y """
435         pass
436 
437     def __format__(self, format_spec):  
438         """
439         S.__format__(format_spec) -> string
440         
441         Return a formatted version of S as described by format_spec.
442         """
443         return ""
444 
445     def __getattribute__(self, name):  
446         """ x.__getattribute__('name') <==> x.name """
447         pass
448 
449     def __getitem__(self, y):  
450         """ x.__getitem__(y) <==> x[y] """
451         pass
452 
453     def __getnewargs__(self, *args, **kwargs): # real signature unknown
454         pass
455 
456     def __getslice__(self, i, j):  
457         """
458         x.__getslice__(i, j) <==> x[i:j]
459                    
460                    Use of negative indices is not supported.
461         """
462         pass
463 
464     def __ge__(self, y):  
465         """ x.__ge__(y) <==> x>=y """
466         pass
467 
468     def __gt__(self, y):  
469         """ x.__gt__(y) <==> x>y """
470         pass
471 
472     def __hash__(self):  
473         """ x.__hash__() <==> hash(x) """
474         pass
475 
476     def __init__(self, string=''): # known special case of str.__init__
477         """
478         str(object='') -> string
479         
480         Return a nice string representation of the object.
481         If the argument is a string, the return value is the same object.
482         # (copied from class doc)
483         """
484         pass
485 
486     def __len__(self):  
487         """ x.__len__() <==> len(x) """
488         pass
489 
490     def __le__(self, y):  
491         """ x.__le__(y) <==> x<=y """
492         pass
493 
494     def __lt__(self, y):  
495         """ x.__lt__(y) <==> x<y """
496         pass
497 
498     def __mod__(self, y):  
499         """ x.__mod__(y) <==> x%y """
500         pass
501 
502     def __mul__(self, n):  
503         """ x.__mul__(n) <==> x*n """
504         pass
505 
506     @staticmethod # known case of __new__
507     def __new__(S, *more):  
508         """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
509         pass
510 
511     def __ne__(self, y):  
512         """ x.__ne__(y) <==> x!=y """
513         pass
514 
515     def __repr__(self):  
516         """ x.__repr__() <==> repr(x) """
517         pass
518 
519     def __rmod__(self, y):  
520         """ x.__rmod__(y) <==> y%x """
521         pass
522 
523     def __rmul__(self, n):  
524         """ x.__rmul__(n) <==> n*x """
525         pass
526 
527     def __sizeof__(self):  
528         """ S.__sizeof__() -> size of S in memory, in bytes """
529         pass
530 
531     def __str__(self):  
532         """ x.__str__() <==> str(x) """
533         pass

str

 

字符串的功能

首字母大小寫
去空格
所有變大小寫
替換
是否爲數字，字母
是否以什麼開頭，或者結尾
查找字符
查找一個字符出現的次數
格式化
編碼解碼
居中，居左，居右
連接，將列表轉換成字符串

 

%s字符串格式化拼接，將幾個字符串拼接在一塊兒
%s爲佔位符，就是佔位的做用，主意：佔位符與佔位符之間還能夠加一個分隔符
%()引用數據到佔位符
若是有幾個字符串須要拼接
拼接格式:
"佔位符要引用幾個字符串就寫幾個佔位符" %(要引用的字符串變量)

注意：

%s能接受任何類型

%d只能接受整數類型

%f只能接受浮點數類型

#!/usr/bin/env python
# -*- coding:utf8 -*-
"""
%s字符串格式化拼接，將幾個字符串拼接在一塊兒
%s爲佔位符，就是佔位的做用，主意：佔位符與佔位符之間還能夠加一個分隔符
%()引用數據到佔位符
若是有幾個字符串須要拼接
拼接格式:
"佔位符要引用幾個字符串就寫幾個佔位符" %(要引用的字符串變量)
"""
a = "你好"
b = "我好"
c = "你們好"
d = "%s%s%s" %(a, b, c)
print(d)
#輸出
#你好我好你們好

 

format()保留一個浮點數，小數點後多少位數 

用字符串格式化來保留小數點後多少位數

#!/usr/bin/env python
# -*- coding:utf-8 -*-
"""用字符串格式化來保留小數點後多少位數"""
b = 7.88123 #建立一個浮點數
c = "{:.2f}".format(b) #用字符串格式化佔位符來處理，{}佔位符用來接收format()函數裏的值，將要處理的變量傳入format()函數，f表示接受浮點數，2f表示接受浮點數保留小數點後兩位
print(c) #打印出浮點數，保留小數點後兩位
# 輸出
# 7.88