Python简单实现阿拉伯数字和罗马数字的互相转换功能示例

#!usr/bin/env python
#encoding:utf-8
'''''
__Author__:沂水寒城
功能：阿拉伯数字和罗马数字的互相转换
'''
def transform_alabo2_roman_num(one_num):
  '''''
  将阿拉伯数字转化为罗马数字
  '''
  num_list=[1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
  str_list=["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"]
  res=''
  for i in range(len(num_list)):
    while one_num>=num_list[i]:
      one_num-=num_list[i]
      res+=str_list[i]
  return res
def transform_roman_num2_alabo(one_str):
  '''''
  将罗马数字转化为阿拉伯数字
  '''
  define_dict={'I':1,'V':5,'X':10,'L':50,'C':100,'D':500,'M':1000}
  if one_str=='0':
    return 0
  else:
    res=0
    for i in range(0,len(one_str)):
      if i==0 or define_dict[one_str[i]]<=define_dict[one_str[i-1]]:
        res+=define_dict[one_str[i]]
      else:
        res+=define_dict[one_str[i]]-2*define_dict[one_str[i-1]]
    return res
    # #下面这种写法也可以
    # for i in range(len(one_str)):
    #   if i > 0 and define_dict[one_str[i]] > define_dict[one_str[i - 1]]:
    #     res -= define_dict[one_str[i - 1]]
    #     res += define_dict[one_str[i]] - define_dict[one_str[i - 1]]
    #   else:
    #     res += define_dict[one_str[i]]
    # return res
if __name__ == '__main__':
  print '**************将罗马数字转化为阿拉伯数字**************'
  one_str_list=['DII','XV','MDCLXVI','XII','VIII','XCIX','XII']
  for one_str in one_str_list:
    print one_str,'----->',transform_roman_num2_alabo(one_str)
  print '**************将阿拉伯数字转化为罗马数字**************'
  one_num_list=[77,66,55,8,1200,34,65,3,21,99]
  for one_num in one_num_list:
    print one_num,'----->',transform_alabo2_roman_num(one_num)