将阿拉伯数字转换成中文

源文出版：http://darkbull.net/101/%E5%B0%86%E9%98%BF%E6%8B%89%E4%BC%AF%E6%95%B0%E5%AD%97%E8%BD%AC%E6%8D%A2%E6%88%90%E4%B8%AD%E6%96%87

周末在家，写了个小程序，用于将阿拉伯数字转换化大写中文。程序没经过任何优化，出没经过详细的测试，挂到网上，方便将来有需要的时候直接拿来用。

源码
测试代码

#!/usr/bin/python
#-*- encoding: utf-8 -*-

import types

class NotIntegerError(Exception):
    pass

class OutOfRangeError(Exception):
    pass

_MAPPING = (u'零', u'一', u'二', u'三', u'四', u'五', u'六', u'七', u'八', u'九', )
_P0 = (u'', u'十', u'百', u'千', )
_S4, _S8, _S16 = 10 ** 4 , 10 ** 8, 10 ** 16
_MIN, _MAX = 0, 9999999999999999

def _to_chinese4(num):
    '''转换[0, 10000)之间的阿拉伯数字
    '''
    assert(0 <= num and num < _S4)
    if num < 10:
        return _MAPPING[num]
    else:
        lst = [ ]
        while num >= 10:
            lst.append(num % 10)
            num = num / 10
        lst.append(num)
        c = len(lst)    # 位数
        result = u''
        
        for idx, val in enumerate(lst):
            if val != 0:
                result += _P0[idx] + _MAPPING[val]
                if idx < c - 1 and lst[idx + 1] == 0:
                    result += u'零'
        
        return result[::-1].replace(u'一十', u'十')
        
def _to_chinese8(num):
    assert(num < _S8)
    to4 = _to_chinese4
    if num < _S4:
        return to4(num)
    else:
        mod = _S4
        high, low = num / mod, num % mod
        if low == 0:
            return to4(high) + u'万'
        else:
            if low < _S4 / 10:
                return to4(high) + u'万零' + to4(low)
            else:
                return to4(high) + u'万' + to4(low)
            
def _to_chinese16(num):
    assert(num < _S16)
    to8 = _to_chinese8
    mod = _S8
    high, low = num / mod, num % mod
    if low == 0:
        return to8(high) + u'亿'
    else:
        if low < _S8 / 10:
            return to8(high) + u'亿零' + to8(low)
        else:
            return to8(high) + u'亿' + to8(low)
       
def to_chinese(num):
    if type(num) != types.IntType and type(num) != types.LongType:
        raise NotIntegerError(u'%s is not a integer.' % num)
    if num < _MIN or num > _MAX:
        raise OutOfRangeError(u'%d out of range[%d, %d)' % (num, _MIN, _MAX))
    
    if num < _S4:
        return _to_chinese4(num)
    elif num < _S8:
        return _to_chinese8(num)
    else:
        return _to_chinese16(num)
    
if __name__ == '__main__':
    print to_chinese(9000)