一、int的范围
2.7：
32位：-231~231-1 64位：-263~263-1
3.5:
在3.5中init长度理论上是无限的
二、python内存机制
在一般情况下当变量被赋值后，内存和变量的关系如下：
#方式一
n1 = 123
n2 = 123
#方式二
n1 = 123
n2 = n1
python内的优化机制（不论是2.7还是3.5都有）：
在-5~257之间的数，如果使用第一种赋值方式，那么他们依然属于同一块内存
print(id(n1)) #查看变量的内存地址
二、进制转换
bin() #把变量转换为2进制
oct() #把变量转换为8进制
int() #把变量转换为10进制
hex() #把变量转换为16进制
三、源码
class int(object):
"""
int(x=0) -> integer
int(x, base=10) -> integer
Convert a number or string to an integer, or return 0 if no arguments
are given. If x is a number, return x.__int__(). For floating point
numbers, this truncates towards zero.
If x is not a number or if base is given, then x must be a string,
bytes, or bytearray instance 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): ; restored from __doc__
"""
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):
""" Returns self, the complex conjugate of any int. """
pass
@classmethod # known case
def from_bytes(cls, bytes, byteorder, *args, **kwargs): ; NOTE: unreliably restored from __doc__
"""
int.from_bytes(bytes, byteorder, *, signed=False) -> int
Return the integer represented by the given array of bytes.
The bytes argument must be a bytes-like object (e.g. bytes or bytearray).
The byteorder argument determines the byte order used to represent the
integer. If byteorder is 'big', the most significant byte is at the
beginning of the byte array. If byteorder is 'little', the most
significant byte is at the end of the byte array. To request the native
byte order of the host system, use `sys.byteorder' as the byte order value.
The signed keyword-only argument indicates whether two's complement is
used to represent the integer.
"""
pass
def to_bytes(self, length, byteorder, *args, **kwargs): ; NOTE: unreliably restored from __doc__
"""
int.to_bytes(length, byteorder, *, signed=False) -> bytes
Return an array of bytes representing an integer.
The integer is represented using length bytes. An OverflowError is
raised if the integer is not representable with the given number of
bytes.
The byteorder argument determines the byte order used to represent the
integer. If byteorder is 'big', the most significant byte is at the
beginning of the byte array. If byteorder is 'little', the most
significant byte is at the end of the byte array. To request the native
byte order of the host system, use `sys.byteorder' as the byte order value.
The signed keyword-only argument determines whether two's complement is
used to represent the integer. If signed is False and a negative integer
is given, an OverflowError is raised.
"""
pass
def __abs__(self, *args, **kwargs):
""" abs(self) """
pass
def __add__(self, *args, **kwargs):
""" Return self+value. """
pass
def __and__(self, *args, **kwargs):
""" Return self&value. """
pass
def __bool__(self, *args, **kwargs):
""" self != 0 """
pass
def __ceil__(self, *args, **kwargs):
""" Ceiling of an Integral returns itself. """
pass
def __divmod__(self, *args, **kwargs):
""" Return divmod(self, value). """
pass
def __eq__(self, *args, **kwargs):
""" Return self==value. """
pass
def __float__(self, *args, **kwargs):
""" float(self) """
pass
def __floordiv__(self, *args, **kwargs):
""" Return self//value. """
pass
def __floor__(self, *args, **kwargs):
""" Flooring an Integral returns itself. """
pass
def __format__(self, *args, **kwargs):
pass
def __getattribute__(self, *args, **kwargs):
""" Return getattr(self, name). """
pass
def __getnewargs__(self, *args, **kwargs):
pass
def __ge__(self, *args, **kwargs):
""" Return self>=value. """
pass
def __gt__(self, *args, **kwargs):
""" Return self>value. """
pass
def __hash__(self, *args, **kwargs):
""" Return hash(self). """
pass
def __index__(self, *args, **kwargs):
""" Return self converted to an integer, if self is suitable for use as an index into a list. """
pass
def __init__(self, x, base=10): # known special case of int.__init__
"""
int(x=0) -> integer
int(x, base=10) -> integer
Convert a number or string to an integer, or return 0 if no arguments
are given. If x is a number, return x.__int__(). For floating point
numbers, this truncates towards zero.
If x is not a number or if base is given, then x must be a string,
bytes, or bytearray instance 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, *args, **kwargs):
""" int(self) """
pass
def __invert__(self, *args, **kwargs):
""" ~self """
pass
def __le__(self, *args, **kwargs):
""" Return self<=value. """
pass
def __lshift__(self, *args, **kwargs):
""" Return self<<value. """
pass
def __lt__(self, *args, **kwargs):
""" Return self<value. """
pass
def __mod__(self, *args, **kwargs):
""" Return self%value. """
pass
def __mul__(self, *args, **kwargs):
""" Return self*value. """
pass
def __neg__(self, *args, **kwargs):
""" -self """
pass
@staticmethod # known case of __new__
def __new__(*args, **kwargs):
""" Create and return a new object. See help(type) for accurate signature. """
pass
def __ne__(self, *args, **kwargs):
""" Return self!=value. """
pass
def __or__(self, *args, **kwargs):
""" Return self|value. """
pass
def __pos__(self, *args, **kwargs):
""" +self """
pass
def __pow__(self, *args, **kwargs):
""" Return pow(self, value, mod). """
pass
def __radd__(self, *args, **kwargs):
""" Return value+self. """
pass
def __rand__(self, *args, **kwargs):
""" Return value&self. """
pass
def __rdivmod__(self, *args, **kwargs):
""" Return divmod(value, self). """
pass
def __repr__(self, *args, **kwargs):
""" Return repr(self). """
pass
def __rfloordiv__(self, *args, **kwargs):
""" Return value//self. """
pass
def __rlshift__(self, *args, **kwargs):
""" Return value<<self. """
pass
def __rmod__(self, *args, **kwargs):
""" Return value%self. """
pass
def __rmul__(self, *args, **kwargs):
""" Return value*self. """
pass
def __ror__(self, *args, **kwargs):
""" Return value|self. """
pass
def __round__(self, *args, **kwargs):
"""
Rounding an Integral returns itself.
Rounding with an ndigits argument also returns an integer.
"""
pass
def __rpow__(self, *args, **kwargs):
""" Return pow(value, self, mod). """
pass
def __rrshift__(self, *args, **kwargs):
""" Return value>>self. """
pass
def __rshift__(self, *args, **kwargs):
""" Return self>>value. """
pass
def __rsub__(self, *args, **kwargs):
""" Return value-self. """
pass
def __rtruediv__(self, *args, **kwargs):
""" Return value/self. """
pass
def __rxor__(self, *args, **kwargs):
""" Return value^self. """
pass
def __sizeof__(self, *args, **kwargs):
""" Returns size in memory, in bytes """
pass
def __str__(self, *args, **kwargs):
""" Return str(self). """
pass
def __sub__(self, *args, **kwargs):
""" Return self-value. """
pass
def __truediv__(self, *args, **kwargs):
""" Return self/value. """
pass
def __trunc__(self, *args, **kwargs):
""" Truncating an Integral returns itself. """
pass
def __xor__(self, *args, **kwargs):
""" Return self^value. """
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"""