第十三节，基本数据类型，数字int字符串str

基本数据类型

　　数字　　　　　int

　　字符串　　　　str

　　布尔值　　　　bool

　　列表　　　　　list

　　元组　　　　　tuple

　　字典　　　　　dict

数据类型关系图

查看一个对象的类

　　如：如查看对象变量a是什么类用到函数type(),函数值是要查看的对象变量

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

　　如上就会输出：<type 'str'> str是字符串类

　　查看一个对象类的类库

　　如上列，查到对象的类后，将类名称写在下面，按着ctrl键用鼠标点击这个类名称，就可以进入这个类的类库

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = type(a)
5 print(b)
6 str      #按着ctrl键用鼠标点击这个类名称，就可以进入这个类的类库

每一个类的类库里都有操作对象的各种功能

　　如：将小写字母转换大写字母

　　调用功能书写格式：（对象变量.功能函数)

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

　如上列a为字符串类的对象变量，upper()为字符串类的类库功能函数，b=a.upper() 打印b就将字符串转换成大写的了，输出NIH

查看一个对象功能函数

　　如：上列　

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = a.upper()  #按着ctrl键用鼠标点击这个对象功能函数，就可以进入这个类的类库，找到对应的函数源码
5 print(b)

　　按着ctrl键用鼠标点击这个对象功能函数，就可以进入这个类的类库，找到对应的函数源码

查看一个对象的类库里具备哪些功能

　　如：

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = dir(a)  
5 print(b)
6 #运行后打印出对象类库的所有具备功能

　　这样就会得到：['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__',等等

查看一个对象类库的所有功能与详情使用方法等

　　如：

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nih"
4 b = help(type(a))
5 print(b)
6 #运行后打印出对象类库的所有具备功能

基本数据，对象类库里的常用功能

　　注意:对象类库里的功能函数，前后带有下划线的为特殊函数，是python程序的内置函数

　　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，其实内部计算流程是
 7 a = 123
 8 b = 456
 9 print(a.__add__(b))
10 #所以两个结果是一样的

　　所以目前可以不用管它

打印出对象在内存的地址

id()

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

　　1.整数，int

　　　　创建整数对象

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)

特别说明：所有以类名称加（）创建的一个类对象都是执行的类库里的（__init__ ）这个功能,初始化的意思

如：

int(123) 执行的对应功能是 __init__

然而 a = 123 又是转换成 a = int(123) 最后还是执行的__init__ 这个功能

其他类也是如此，每一个类都有__init__ 初始化

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

　　　　bit_length()　　　取二进制的最小表示位数（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): 
        """ 返回表示该数字的时占用的最少位数 """
        """
        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
        """ 返回该复数的共轭复数 """
        """ Returns self, the complex conjugate of any int. """
        pass

    def __abs__(self):
        """ 返回绝对值 """
        """ 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): 
        """ 比较两个数大小 """
        """ x.__cmp__(y) <==> cmp(x,y) """
        pass

    def __coerce__(self, y):
        """ 强制生成一个元组 """ 
        """ x.__coerce__(y) <==> coerce(x, y) """
        pass

    def __divmod__(self, y): 
        """ 相除，得到商和余数组成的元组 """ 
        """ x.__divmod__(y) <==> divmod(x, y) """
        pass

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

    def __float__(self): 
        """ 转换为浮点类型 """ 
        """ 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
        """ 内部调用 __new__方法或创建对象时传入参数使用 """ 
        pass

    def __hash__(self): 
        """如果对象object为哈希表类型，返回对象object的哈希值。哈希值为整数。在字典查找中，哈希值用于快速比较字典的键。两个数值如果相等，则哈希值也相等。"""
        """ x.__hash__() <==> hash(x) """
        pass

    def __hex__(self): 
        """ 返回当前数的 十六进制 表示 """ 
        """ x.__hex__() <==> hex(x) """
        pass

    def __index__(self): 
        """ 用于切片，数字无意义 """
        """ x[y:z] <==> x[y.__index__():z.__index__()] """
        pass

    def __init__(self, x, base=10): # known special case of int.__init__
        """ 构造方法，执行 x = 123 或 x = int(10) 时，自动调用，暂时忽略 """ 
        """
        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): 
        """ 转换为整数 """ 
        """ x.__int__() <==> int(x) """
        pass

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

    def __long__(self): 
        """ 转换为长整数 """ 
        """ 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 八进制 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): 
        """ 幂，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): 
        """转化为解释器可读取的形式 """
        """ x.__repr__() <==> repr(x) """
        pass

    def __str__(self): 
        """转换为人阅读的形式，如果没有适于人阅读的解释形式的话，则返回解释器课阅读的形式"""
        """ 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): 
        """ 返回数值被截取为整形的值，在整形中无意义 """
        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
    """ 虚数，无意义 """
    """the imaginary part of a complex number"""

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

    real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 实属，无意义 """
    """the real part of a complex number"""

int

　2.字符串，str

　　　　字符串常用功能：
　　　　移除空白
　　　　分割
　　　　长度
　　　　索引：注意2.7版本索引中文字符串会乱码，3.0版本以上没问题
　　　　切片

　　创建字符串

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()　　　　首字母大写　　　　格式：a.capitalize()

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

　　　　center(self, width, fillchar=None) 有参

　　　　""" （内容居中），width：总长度；fillchar：空白处填充内容，默认无 """

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

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

　　　　""" （查找字符在字符串属性次数），要查找的字符，查找范围开始位置，查找范围结束位置 """ （也就是查找一个或者多个字符，在一个字符串的出现次数）

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林贵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现的次数 2

　　　　注意一个中文字符，算3个字符，空格也算一个字符

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

　　　　返回：真或者假

　　　　""" （是否以 xxx 结束），要判断的字符，判断范围开始位置，判断范围结束位置 """

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 a = "nihzhongguo"
 4 b = a.endswith("o")
 5 print(b)
 6 #判断字符串是否是o结尾打印出True
 7 
 8 a = "nihzhongguo"
 9 b = a.endswith("o", 0, 5)
10 print(b)
11 #判断字符串从0到第5个位置是否是以o结尾 打印出False

　　　　expandtabs(self, tabsize=None)有参

　　　　""" （将tab转换成空格，默认一个tab转换成8个空格），自定义换成空格数 """

　　　　注意：表示tab键，如果在编辑器直接tab键，编辑器会自动转换成空格

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nihzh	ongguo"
4 b = a.expandtabs(16)
5 print(b)
6 #将tab键转换成16个空格打印出 nihzh           ongguo
7 #注意如果不指定，默认是8个

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

　　　　""" (寻找字符在字符串里的位置)，要查找的字符，查找字符串起始位置，查找字符串结束位置，如果找到返回位置数，如果没找到，返回 -1 """　　

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "nihzhongguo"
4 b = a.find("o")
5 print(b)
6 #打印输出o在字符串里的位置 5
7 #如果没找到输出的是 -1

　　　　format(*args, **kwargs)有参

　　　 """ （替换字符串里的占位符），动态参数，将函数式编程时细说 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "姓名 {0} 年龄 {1}"
4 #{}站位符里面一般从0编号
5 b = a.format("林贵秀", "30")
6 print(b)
7 #替换字符串里的占位符 输出 姓名 林贵秀 年龄 30

　　　isalnum(self)　

　　　""" （判断字符串是否是纯字母和数字）是纯字母或数字返回真，否则返回假"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林贵秀123aaa"
4 b = a.isalnum()
5 print(b)
6 #输出 False 表示不是纯字母或数字

　　isalpha(self)　　

　　""" （是否是纯字母）是字母返回真，否则返回假 """　

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

　　isdigit(self)

　　 """ （是否是纯数字）是纯数字返回真，否则返回假 """

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

　　islower(self)

　　""" （字符串里的字母是否是纯小写）是返回真，否则返回假 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林贵秀asdd12434346"
4 b = a.islower()
5 print(b)
6 #输出 True 表示是纯小写

　　isspace(self)

　　"""(判断字符串是否是纯空格)是返回真，否则返回假"""

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

　　istitle(self)　

　　"""(判断英文首字母是否大写)是返回真，否则返回假"""

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

　　isupper(self)

　　"""(判断是否全部字母是大写)是返回真，否则返回假"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "NGGGEAWG"
4 b = a.isupper()
5 print(b)
6 #输出 True 表示字母全部是大写

　　join(self, iterable)有参

　　""" （连接一个列表成一串字符串）"链接符".join(字符串变量)"""

　　注意：如果链接符 " " 为空，链接起来就是一串没有链接符的字符串

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = ["李彦宏" , "马云" , "周鸿祎"]
4 b = "|".join(a)
5 print(b)
6 #输出 李彦宏|马云|周鸿祎  将列表链接成一串字符串

　　ljust(self, width, fillchar=None)

　　""" （内容左对齐，右侧填充）宽度，填充符 """

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

　　lower(self)

　　""" （字符串变小写）"""

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

　　lstrip(self, chars=None)

　　 """ （移除左侧空白）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "  林贵秀  "
4 b = a.lstrip()
5 print(b)
6 #输出 林贵秀  去除左边空格

　　rstrip(self, chars=None)

　　 """ （移除右侧空白）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "  林贵秀  "
4 b = a.rstrip()
5 print(b)
6 #输出   林贵秀 去除右边空格

　　strip(self, chars=None)

　　 """ （移除两边空白）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "  林贵秀  "
4 b = a.strip()
5 print(b)
6 #输出 林贵秀 去除两边空格

　　partition(self, sep)有参

　　 """ （分割，前，中，后三部分）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 #输出 ('abc', 'def', 'jhi') 从位置字符那里分割，返回元组

　　replace(self, old, new, count=None)

　　"""（替换）字符串里被替换的字符，替换成什么字符，可选：位置从左向右找几个 """

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "林贵秀30岁了"
4 b = a.replace("30", "20")
5 print(b)
6 #输出 林贵秀20岁了 将字符串里的字符替换成指定字符

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

　　 """ （分割字符串），要分割的标示字符，标示字符分割有效位置：也就是从左边开始最多分割几次 """

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

　　splitlines(self, keepends=False)

　　""" （根据换行分割） """

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

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

　　""" （判断是否以某一个字符或者字符串起始）要判断的字符或字符串：返回真或者假 """

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

　　swapcase(self)

　　""" （大写变小写，小写变大写）"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "abcdABCD"
4 b = a.swapcase()
5 print(b)
6 #输出 ABCDabcd 返回大写变小写，小写变大写

　　索引　

　　索引：把一串字符串分成每个字符为一个新字符串

索引：注意2.7版本索引中文字符串会乱码，3.0版本以上没问题 (2.7是以字节编码的，3.0是以字符编码的)

说明：2.7版本中文是以字节编码的，如utf-8 一个中文是3个字节，所以当索引字符下标是一个汉字是有3个下标的，索引一个下标不是一个完整的汉字，就会出现乱码

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = "你好"
4 print(a[0])#索引一个下标不是一个完整的汉字，就会出现乱码

2.7版本中，用切片的方法打印一个汉字

说明：切片可以指定字符下标范围，如utf-8 一个中文是3个字节，如果0到3的范围，刚好是一个字

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，因为utf-8字符编码一个汉字3个字节

　　判断索引数用 len() 函数一般配合循环使用

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 #索引：把一串字符串分成每个字符为一个新字符串
 4 #以字符下标位置分开
 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 四个独立的新字符串
11 
12 #判断一个字符串有多少个下标字符如下
13 a = "adce"
14 b = len(a)
15 print(b)
16 #输出 4 也就是说这个字符串有4个下标字符

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

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 #索引：结合循环应用
4 # #for循环
5 #b为循环自定义变量
6 a = "hfewfhopghg0u9o0gh0ghgygh0329gh0392gh0239g2g"
7 for b in a:
8     print(b)
9 #循环出索引

　　切片　　

　　切片：把一串字符串分成每几个字符或者多个字符，为一个新字符串
　　以字一个字符的下标开始，和一个字符的下标结束，切成一串新的字符串　

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 #切片：把一串字符串分成每几个字符或者多个字符，为一个新字符串
4 #以字一个字符的下标开始，和一个字符的下标结束，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 切成四个独立的新字符串

bytes字节类型 3.5版本有效

"""(将字符串转换成16进制，要转换的字符串变量,encoding='字符编码')"""

1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 #bytes类,将字符串转换成16进制表示
4 #将字符串转换成16进制表示
5 a = "林贵秀"
6 a1 = bytes(a,encoding='utf-8')
7 print(a1)
8 a2 = bytes(a,encoding='gbk')
9 print(a2)

str 字符串类型，将字节表示的16进制转换成字符串

"""(16进制字节转换成字符串，16进制变量,encoding='字符编码')"""

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 #str将16进制转换成字符串
 4 b = "林贵秀"
 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)

将字符串，转换成16进制，10进制，二进制

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 #bytes类,将字符串转换成16进制表示
 4 a = "李露"
 5 print(a)#字符串表示
 6 #输出 李露
 7 
 8 #用bytes类，将字符串转换成16进制
 9 print(bytes(a,encoding='utf-8'))#将字符串转换成16进制表示
10 #输出 b'xe4xbdxa0xe5xa5xbd'  16进制表示的二进制
11 
12 #用for将16进制循环出10进制
13 b = bytes(a,encoding='utf-8')#将16进制转换成10进制
14 for i in b:#for循环16进制的时候默认会以10进制方式循环出数据
15     print(i)
16 #输出
17 # 230
18 # 157
19 # 142
20 # 233
21 # 156
22 # 178
23 
24 #用bin将10进制转换成二进制
25 c = bytes(a,encoding='utf-8')
26 for i in c:
27     print(i,bin(i))
28 #输出
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         """ 首字母变大写 """
 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         """ 内容居中，width：总长度；fillchar：空白处填充内容，默认无 """
 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         """ 子序列个数 """
 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         """ 解码 """
 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         """ 编码，针对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 结束 """
 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         """ 将tab转换成空格，默认一个tab转换成8个空格 """
 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         """ 寻找子序列位置，如果没找到，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，动态参数，将函数式编程时细说 """
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，如果没找到，报错 """
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         """ 是否是字母和数字 """
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         """ 是否是字母 """
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         """ 是否是数字 """
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         """ 是否小写 """
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         """ 连接 """
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         """ 内容左对齐，右侧填充 """
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         """ 变小写 """
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         """ 移除左侧空白 """
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，后三部分 """
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         """ 替换 """
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最多分割几次 """
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         """ 根据换行分割 """
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         """ 移除两段空白 """
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         """ 大写变小写，小写变大写 """
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         转换，需要先做一个对应表，最后一个表示删除字符集合
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         """方法返回指定长度的字符串，原字符串右对齐，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

首字母大小写
去空格
全部变大小写
替换
是否为数字，字母
是否以什么开头，或者结尾
查找字符
查找一个字符出现的次数
格式化
编码解码
居中，居左，居右
链接，将列表转换成字符串

%s字符串格式化拼接，将几个字符串拼接在一起
%s为占位符，就是占位的作用，主意：占位符与占位符之间还可以加一个分隔符
%()引用数据到占位符
如果有几个字符串需要拼接
拼接格式:
"占位符要引用几个字符串就写几个占位符" %(要引用的字符串变量)

注意：

%s能接受任何类型

%d只能接受整数类型

%f只能接受浮点数类型

#!/usr/bin/env python
# -*- coding:utf8 -*-
"""
%s字符串格式化拼接，将几个字符串拼接在一起
%s为占位符，就是占位的作用，主意：占位符与占位符之间还可以加一个分隔符
%()引用数据到占位符
如果有几个字符串需要拼接
拼接格式:
"占位符要引用几个字符串就写几个占位符" %(要引用的字符串变量)
"""
a = "你好"
b = "我好"
c = "大家好"
d = "%s%s%s" %(a, b, c)
print(d)
#输出
#你好我好大家好

format()保留一个浮点数，小数点后多少位数

用字符串格式化来保留小数点后多少位数

#!/usr/bin/env python
# -*- coding:utf-8 -*-
"""用字符串格式化来保留小数点后多少位数"""
b = 7.88123 #创建一个浮点数
c = "{:.2f}".format(b) #用字符串格式化占位符来处理，{}占位符用来接收format()函数里的值，将要处理的变量传入format()函数，f表示接受浮点数，2f表示接受浮点数保留小数点后两位
print(c) #打印出浮点数，保留小数点后两位
# 输出
# 7.88