本文介绍了Python中变量作用域的定义及其修改方式，包括def、class、lambda等的作用，并探讨了不同进制之间的区别及Python中的表示方法。
变量的作用域
# python能够改变变量作用域的代码段是def、class、lamda.
# if/elif/else、try/except/finally、for/while 并不能涉及变量作用域的更改，也就是说他们的代码块中的变量，在外部也是可以访问的
# 变量搜索路径是：本地变量->全局变量
#只要内存中存在，则就可用。
#################################################################
三元运算符
python中的三元运算和其他语言的三元运算有一些区别
其实现形式如下：
reulst = var1 if condition else var2
# 如果condition 为真值 则 result 的值为 var1 ， 如果condition的值为假，则 result 的结果为var2
##################################################################
进制（进制位）
不同进制的区别在于书运算时，逢几进一，几进制就是逢几进一，
二进制 ：表示数字 0和1；python中以 0b 开头
八进制 ： 表示数字01234567,；python中以0开头
十进制 ：
十六进制 ：表示数字0123456789ABCDEF，python以0x开头
#####################################################################
python基础
概念：在python中一切事物都是对象，对象基于类来创建，（以后详细说明）；
python使用对象模型来存储数据，构造任何类型的值都是一个对象，所以，在python的世界里，一切皆对象，一个整数是一个对象，一张各字符串也是一个对象，一个类型也是一个对象......
类：具有同种属性的对象称为类，是一个抽象的概念，例：汽车、人、牛、
对象：类的实例化，例：黄种人、黑人、白人等都是人的实例化，
######################################################################
提前准备知识：
type() # 查看对象类型，例： type(lst)
dir() #查看类的方法列表，例：dir(lst)
help() #查看类的详细信息，例：help(lst)
help() #查看类方法的信息，例：help(lst)
#####################################################################
int 型
##
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): # real signature unknown; restored from __doc__
"""
int.bit_length() -> int
Number of bits necessary to represent self in binary.
返回表示该数字时 的占用的最小位数（二进制）
>>> bin(37)
'0b100101'
>>> (37).bit_length()
6
"""
return 0
def conjugate(self, *args, **kwargs): # real signature unknown
""" Returns self, the complex conjugate of any int.
返回共轭复数
"""
pass
def __abs__(self): # real signature unknown; restored from __doc__
""" x.__abs__() <==> abs(x)
返回 绝对值
"""
pass
def __add__(self, y): # real signature unknown; restored from __doc__
""" x.__add__(y) <==> x+y
求和
"""
pass
def __and__(self, y): # real signature unknown; restored from __doc__
""" x.__and__(y) <==> x&y """
pass
def __cmp__(self, y): # real signature unknown; restored from __doc__
""" x.__cmp__(y) <==> cmp(x,y)
比较大小， 大于、等于、小于时 分别返回1 0 -1
"""
pass
def __coerce__(self, y): # real signature unknown; restored from __doc__
""" x.__coerce__(y) <==> coerce(x, y)
强制返回x和y组成的一个元组
"""
pass
def __divmod__(self, y): # real signature unknown; restored from __doc__
""" x.__divmod__(y) <==> divmod(x, y)
返回x和y相除以后，商和余数组成的元组
"""
pass
def __div__(self, y): # real signature unknown; restored from __doc__
""" x.__div__(y) <==> x/y """
pass
def __float__(self): # real signature unknown; restored from __doc__
""" x.__float__() <==> float(x)
转换为浮点类型
"""
pass
def __floordiv__(self, y): # real signature unknown; restored from __doc__
""" x.__floordiv__(y) <==> x//y """
pass
def __format__(self, *args, **kwargs): # real signature unknown
pass
def __getattribute__(self, name): # real signature unknown; restored from __doc__
""" x.__getattribute__('name') <==> x.name """
pass
def __getnewargs__(self, *args, **kwargs): # real signature unknown
“”“ 内部调用， __new__ 方法或者闯将对象时，传入参数使用 ”“”
pass
def __hash__(self): # real signature unknown; restored from __doc__
""" x.__hash__() <==> hash(x)
如果对象 object为哈希表类型，则返回对象object的哈希值，哈希值为整数，
在字典中查找时，哈希值用于快速比较两个字典的键，如果两个键相等，则哈希值也相等
"""
pass
def __hex__(self): # real signature unknown; restored from __doc__
""" x.__hex__() <==> hex(x)
返回当前值的 16进制 表示的数
"""
pass
def __index__(self): # real signature unknown; restored from __doc__
""" x[y:z] <==> x[y.__index__():z.__index__()]
用于切片，数字无意义
"""
pass
def __init__(self, x, base=10): # known special case of int.__init__
"""
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)
构造方法，执行x=123 或者 x=int(10) 时 自动调用
"""
pass
def __int__(self): # real signature unknown; restored from __doc__
""" x.__int__() <==> int(x) """
pass
def __invert__(self): # real signature unknown; restored from __doc__
""" x.__invert__() <==> ~x """
pass
def __long__(self): # real signature unknown; restored from __doc__
""" x.__long__() <==> long(x) """
pass
def __lshift__(self, y): # real signature unknown; restored from __doc__
""" x.__lshift__(y) <==> x<<y """
pass
def __mod__(self, y): # real signature unknown; restored from __doc__
""" x.__mod__(y) <==> x%y """
pass
def __mul__(self, y): # real signature unknown; restored from __doc__
""" x.__mul__(y) <==> x*y """
pass
def __neg__(self): # real signature unknown; restored from __doc__
""" x.__neg__() <==> -x """
pass
@staticmethod # known case of __new__
def __new__(S, *more): # real signature unknown; restored from __doc__
""" T.__new__(S, ...) -> a new object with type S, a subtype of T """
pass
def __nonzero__(self): # real signature unknown; restored from __doc__
""" x.__nonzero__() <==> x != 0 """
pass
def __oct__(self): # real signature unknown; restored from __doc__
""" x.__oct__() <==> oct(x)
返回 该数字的 八进制 表示的数
"""
pass
def __or__(self, y): # real signature unknown; restored from __doc__
""" x.__or__(y) <==> x|y """
pass
def __pos__(self): # real signature unknown; restored from __doc__
""" x.__pos__() <==> +x """
pass
def __pow__(self, y, z=None): # real signature unknown; restored from __doc__
""" x.__pow__(y[, z]) <==> pow(x, y[, z])
幂运算、次方运算
"""
pass
def __radd__(self, y): # real signature unknown; restored from __doc__
""" x.__radd__(y) <==> y+x """
pass
def __rand__(self, y): # real signature unknown; restored from __doc__
""" x.__rand__(y) <==> y&x """
pass
def __rdivmod__(self, y): # real signature unknown; restored from __doc__
""" x.__rdivmod__(y) <==> divmod(y, x) """
pass
def __rdiv__(self, y): # real signature unknown; restored from __doc__
""" x.__rdiv__(y) <==> y/x """
pass
def __repr__(self): # real signature unknown; restored from __doc__
""" x.__repr__() <==> repr(x)
转换为解释器可读取的形式
"""
pass
def __rfloordiv__(self, y): # real signature unknown; restored from __doc__
""" x.__rfloordiv__(y) <==> y//x """
pass
def __rlshift__(self, y): # real signature unknown; restored from __doc__
""" x.__rlshift__(y) <==> y<<x """
pass
def __rmod__(self, y): # real signature unknown; restored from __doc__
""" x.__rmod__(y) <==> y%x """
pass
def __rmul__(self, y): # real signature unknown; restored from __doc__
""" x.__rmul__(y) <==> y*x """
pass
def __ror__(self, y): # real signature unknown; restored from __doc__
""" x.__ror__(y) <==> y|x """
pass
def __rpow__(self, x, z=None): # real signature unknown; restored from __doc__
""" y.__rpow__(x[, z]) <==> pow(x, y[, z]) """
pass
def __rrshift__(self, y): # real signature unknown; restored from __doc__
""" x.__rrshift__(y) <==> y>>x """
pass
def __rshift__(self, y): # real signature unknown; restored from __doc__
""" x.__rshift__(y) <==> x>>y """
pass
def __rsub__(self, y): # real signature unknown; restored from __doc__
""" x.__rsub__(y) <==> y-x """
pass
def __rtruediv__(self, y): # real signature unknown; restored from __doc__
""" x.__rtruediv__(y) <==> y/x """
pass
def __rxor__(self, y): # real signature unknown; restored from __doc__
""" x.__rxor__(y) <==> y^x """
pass
def __str__(self): # real signature unknown; restored from __doc__
""" x.__str__() <==> str(x)
转换为人阅读的形式，如果没有适用于人阅读的解释形式的话，则返回解释器可阅读的形式
"""
pass
def __sub__(self, y): # real signature unknown; restored from __doc__
""" x.__sub__(y) <==> x-y """
pass
def __truediv__(self, y): # real signature unknown; restored from __doc__
""" x.__truediv__(y) <==> x/y """
pass
def __trunc__(self, *args, **kwargs): # real signature unknown
""" Truncating an Integral returns itself.
返回该数值被截取为整型的值，整型中无意义
"""
pass
def __xor__(self, y): # real signature unknown; restored from __doc__
""" x.__xor__(y) <==> x^y """
pass
denominator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the denominator of a rational number in lowest terms"""
imag = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the imaginary part of a complex number"""
numerator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the numerator of a rational number in lowest terms"""
real = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the real part of a complex number"""##
#####################################################################
long 型
大部分方法与int型类似，可参考int型
##
class long(object):
"""
long(x=0) -> long
long(x, base=10) -> long
Convert a number or string to a long integer, or return 0L if no arguments
are given. If x is floating point, the conversion truncates towards zero.
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)
4L
"""
def bit_length(self): # real signature unknown; restored from __doc__
"""
long.bit_length() -> int or long
Number of bits necessary to represent self in binary.
>>> bin(37L)
'0b100101'
>>> (37L).bit_length()
6
"""
return 0
def conjugate(self, *args, **kwargs): # real signature unknown
""" Returns self, the complex conjugate of any long. """
pass
def __abs__(self): # real signature unknown; restored from __doc__
""" x.__abs__() <==> abs(x) """
pass
def __add__(self, y): # real signature unknown; restored from __doc__
""" x.__add__(y) <==> x+y """
pass
def __and__(self, y): # real signature unknown; restored from __doc__
""" x.__and__(y) <==> x&y """
pass
def __cmp__(self, y): # real signature unknown; restored from __doc__
""" x.__cmp__(y) <==> cmp(x,y) """
pass
def __coerce__(self, y): # real signature unknown; restored from __doc__
""" x.__coerce__(y) <==> coerce(x, y) """
pass
def __divmod__(self, y): # real signature unknown; restored from __doc__
""" x.__divmod__(y) <==> divmod(x, y) """
pass
def __div__(self, y): # real signature unknown; restored from __doc__
""" x.__div__(y) <==> x/y """
pass
def __float__(self): # real signature unknown; restored from __doc__
""" x.__float__() <==> float(x) """
pass
def __floordiv__(self, y): # real signature unknown; restored from __doc__
""" x.__floordiv__(y) <==> x//y """
pass
def __format__(self, *args, **kwargs): # real signature unknown
pass
def __getattribute__(self, name): # real signature unknown; restored from __doc__
""" x.__getattribute__('name') <==> x.name """
pass
def __getnewargs__(self, *args, **kwargs): # real signature unknown
pass
def __hash__(self): # real signature unknown; restored from __doc__
""" x.__hash__() <==> hash(x) """
pass
def __hex__(self): # real signature unknown; restored from __doc__
""" x.__hex__() <==> hex(x) """
pass
def __index__(self): # real signature unknown; restored from __doc__
""" x[y:z] <==> x[y.__index__():z.__index__()] """
pass
def __init__(self, x=0): # real signature unknown; restored from __doc__
pass
def __int__(self): # real signature unknown; restored from __doc__
""" x.__int__() <==> int(x) """
pass
def __invert__(self): # real signature unknown; restored from __doc__
""" x.__invert__() <==> ~x """
pass
def __long__(self): # real signature unknown; restored from __doc__
""" x.__long__() <==> long(x) """
pass
def __lshift__(self, y): # real signature unknown; restored from __doc__
""" x.__lshift__(y) <==> x<<y """
pass
def __mod__(self, y): # real signature unknown; restored from __doc__
""" x.__mod__(y) <==> x%y """
pass
def __mul__(self, y): # real signature unknown; restored from __doc__
""" x.__mul__(y) <==> x*y """
pass
def __neg__(self): # real signature unknown; restored from __doc__
""" x.__neg__() <==> -x """
pass
@staticmethod # known case of __new__
def __new__(S, *more): # real signature unknown; restored from __doc__
""" T.__new__(S, ...) -> a new object with type S, a subtype of T """
pass
def __nonzero__(self): # real signature unknown; restored from __doc__
""" x.__nonzero__() <==> x != 0 """
pass
def __oct__(self): # real signature unknown; restored from __doc__
""" x.__oct__() <==> oct(x) """
pass
def __or__(self, y): # real signature unknown; restored from __doc__
""" x.__or__(y) <==> x|y """
pass
def __pos__(self): # real signature unknown; restored from __doc__
""" x.__pos__() <==> +x """
pass
def __pow__(self, y, z=None): # real signature unknown; restored from __doc__
""" x.__pow__(y[, z]) <==> pow(x, y[, z]) """
pass
def __radd__(self, y): # real signature unknown; restored from __doc__
""" x.__radd__(y) <==> y+x """
pass
def __rand__(self, y): # real signature unknown; restored from __doc__
""" x.__rand__(y) <==> y&x """
pass
def __rdivmod__(self, y): # real signature unknown; restored from __doc__
""" x.__rdivmod__(y) <==> divmod(y, x) """
pass
def __rdiv__(self, y): # real signature unknown; restored from __doc__
""" x.__rdiv__(y) <==> y/x """
pass
def __repr__(self): # real signature unknown; restored from __doc__
""" x.__repr__() <==> repr(x) """
pass
def __rfloordiv__(self, y): # real signature unknown; restored from __doc__
""" x.__rfloordiv__(y) <==> y//x """
pass
def __rlshift__(self, y): # real signature unknown; restored from __doc__
""" x.__rlshift__(y) <==> y<<x """
pass
def __rmod__(self, y): # real signature unknown; restored from __doc__
""" x.__rmod__(y) <==> y%x """
pass
def __rmul__(self, y): # real signature unknown; restored from __doc__
""" x.__rmul__(y) <==> y*x """
pass
def __ror__(self, y): # real signature unknown; restored from __doc__
""" x.__ror__(y) <==> y|x """
pass
def __rpow__(self, x, z=None): # real signature unknown; restored from __doc__
""" y.__rpow__(x[, z]) <==> pow(x, y[, z]) """
pass
def __rrshift__(self, y): # real signature unknown; restored from __doc__
""" x.__rrshift__(y) <==> y>>x """
pass
def __rshift__(self, y): # real signature unknown; restored from __doc__
""" x.__rshift__(y) <==> x>>y """
pass
def __rsub__(self, y): # real signature unknown; restored from __doc__
""" x.__rsub__(y) <==> y-x """
pass
def __rtruediv__(self, y): # real signature unknown; restored from __doc__
""" x.__rtruediv__(y) <==> y/x """
pass
def __rxor__(self, y): # real signature unknown; restored from __doc__
""" x.__rxor__(y) <==> y^x """
pass
def __sizeof__(self, *args, **kwargs): # real signature unknown
""" Returns size in memory, in bytes """
pass
def __str__(self): # real signature unknown; restored from __doc__
""" x.__str__() <==> str(x) """
pass
def __sub__(self, y): # real signature unknown; restored from __doc__
""" x.__sub__(y) <==> x-y """
pass
def __truediv__(self, y): # real signature unknown; restored from __doc__
""" x.__truediv__(y) <==> x/y """
pass
def __trunc__(self, *args, **kwargs): # real signature unknown
""" Truncating an Integral returns itself. """
pass
def __xor__(self, y): # real signature unknown; restored from __doc__
""" x.__xor__(y) <==> x^y """
pass
denominator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the denominator of a rational number in lowest terms"""
imag = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the imaginary part of a complex number"""
numerator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the numerator of a rational number in lowest terms"""
real = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the real part of a complex number"""##
51cto博客地址
http://timesnotes.blog.51cto.com
http://timesnotes.blog.51cto.com/1079212/1709006
本博客地址：
http://www.timesnotes.com/
http://www.timesnotes.com/?p=72
转载于:https://blog.51cto.com/timesnotes/1709006
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