罗马数字为整数 [英] Roman numbers to integers

问题描述

我有，不幸的是要得到按产品名称匹配的产品转移。这里最大的问题是我可能会重复的产品是考虑罗马数字。有时候，同样的产品将与罗马数字命名，其他时候这将是一个普通的。

I have a transfer with products that unfortunately has to get matched by product name. The biggest issue here is I might get duplicate products on account of roman numbers. Sometimes the same product will be named with a roman number, other times it will be a regular one.

我在使用Google的也许已经取得字符串函数来转换这一点，但没有运气。我想这不会是努力使我自己，但我很想听听你对如何处理这种情况的一些意见，如果你还认识一个已经取得函数，这样做，将其命名为

I was googling for maybe a already made string function to convert this, but had no luck. I guess it wouldn't be that hard to make my own, but I would love to hear some opinions on how to handle the situation, and also if you know an already made function that does this, name it.

编辑：
的产品有移动小工具。示例 - 三星Galaxy SII - 三星Galaxy S2

The products are mobile gadgets. Example - Samsung Galaxy SII - Samsung Galaxy S2

推荐答案

一个更加简单易读C＃实现的：

A more simple and readable C# implementation that:

• 地图我1，V 5，X为10，L 50，C 100，D 500，男为1000。


• 使用一个单一的foreach循环（的foreach 的使用上的宗旨，与前值
  保留）。


• 添加映射号到总。


• 减去两倍的号码前添加，如果I L或C，C前D或M（不是所有的字符都在这里允许！）之前V或X，X之前。


• 返回0（在罗马数字中不使用）对空字符串，打错一个字母
  或不允许的字符用于减法


• 备注：这是还没有完全完成，我们没有检查所有可能的条件，一个有效的输入字符串

• maps I to 1, V to 5, X to 10, L to 50, C to 100, D to 500, M to 1000.
• uses one single foreach loop (foreach used on purpose, with previous value hold).
• adds the mapped number to the total.
• subtracts twice the number added before, if I before V or X, X before L or C, C before D or M (not all chars are allowed here!).
• returns 0 (not used in Roman numerals) on empty string, wrong letter or not allowed char used for subtraction.
• remark: it's still not totally complete, we didn't check all possible conditions for a valid input string!

代码：

private static Dictionary<char, int> _romanMap = new Dictionary<char, int>
{
   {'I', 1}, {'V', 5}, {'X', 10}, {'L', 50}, {'C', 100}, {'D', 500}, {'M', 1000}
};

public static int ConvertRomanToNumber(string text)
{
    int totalValue = 0, prevValue = 0;
    foreach (var c in text)
    {
        if (!_romanMap.ContainsKey(c))
            return 0;
        var crtValue = _romanMap[c];
        totalValue += crtValue;
        if (prevValue != 0 && prevValue < crtValue)
        {
            if (prevValue == 1 && (crtValue == 5 || crtValue == 10)
                || prevValue == 10 && (crtValue == 50 || crtValue == 100)
                || prevValue == 100 && (crtValue == 500 || crtValue == 1000))
                totalValue -= 2 * prevValue;
            else
                return 0;
        }
        prevValue = crtValue;
    }
    return totalValue;
}

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