未绑定的整数类

Question

我正在实现一个UnboundInteger类，它的行为类似于正则整数。这个想法是能够在任意大的范围内进行操作对于支持的大小。

这是我的代码

class UnboundInteger(object):
def __init__(self, integer):
    self.integer = str(integer)

def __add__(self, other):
    carry = '0'
    temp = '0'
    result = ''
    if (len(self.integer) > len(other.integer)):
        num_of_zeros = len(self.integer) - len(other.integer)
        other.integer = '0' * num_of_zeros + other.integer
    elif (len(self.integer < other.integer)):
        num_of_zeros = len(other.integer) - len(self.integer)
        self.integer = '0' * num_of_zeros + self.integer
    for i in range(1, len(self.integer)+1):
        temp = str(int(self.integer[-i]) + int(other.integer[-i]) + int(carry))
        temp = '0' + temp
        temp = temp[-1]
        carry = temp[-2]
        result = temp + result
    return UnboundInteger(result)

@classmethod
def from_int(cls, integer):
    '''
    Take in a integer and build the unbound integer object.
    '''
    ub_integer = cls(integer)
    return ub_integer

很遗憾，我无法调试错误请帮我解决

这是错误

    In [40]: reload(test)
Out[40]: <module 'test' from 'test.py'>
In [41]: a = test.UnboundInteger(1000000000000)
In [42]: b = test.UnboundInteger(20000000000)
In [43]: a + b
---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-43-f96fb8f649b6> in <module>()
----> 1 a + b
/home/neel101/test.py in __add__(self, other)
     17             temp = '0' + temp
     18             temp = temp[-1]
---> 19             carry = temp[-2]
     20             result = temp + result
     21 
IndexError: string index out of range

或者任何更好的方法来解决这个问题。请告诉我！

Answer 1

发生这种情况是因为您正在覆盖临时变量。

temp = '0' + temp
temp = temp[-1]
carry = temp[-2]

应该是这样的：

temp = '0' + temp
carry = temp[-2]
temp = temp[-1]