ahjesus 单词单数-复数相互转换C#

public static class StringUtil
{
/// <summary>
/// 单词变成单数形式
/// </summary>
/// <param name="word"></param>
/// <returns></returns>
public static string ToSingular(string word)
{
Regex plural1 = new Regex("(?<keep>[^aeiou])ies$");
Regex plural2 = new Regex("(?<keep>[aeiou]y)s$");
Regex plural3 = new Regex("(?<keep>[sxzh])es$");
Regex plural4 = new Regex("(?<keep>[^sxzhyu])s$");

if (plural1.IsMatch(word))
return plural1.Replace(word, "${keep}y");
else if (plural2.IsMatch(word))
return plural2.Replace(word, "${keep}");
else if (plural3.IsMatch(word))
return plural3.Replace(word, "${keep}");
else if (plural4.IsMatch(word))
return plural4.Replace(word, "${keep}");

return word;
}
/// <summary>
/// 单词变成复数形式
/// </summary>
/// <param name="word"></param>
/// <returns></returns>
public static string ToPlural(string word)
{
Regex plural1 = new Regex("(?<keep>[^aeiou])y$");
Regex plural2 = new Regex("(?<keep>[aeiou]y)$");
Regex plural3 = new Regex("(?<keep>[sxzh])$");
Regex plural4 = new Regex("(?<keep>[^sxzhy])$");

if (plural1.IsMatch(word))
return plural1.Replace(word, "${keep}ies");
else if (plural2.IsMatch(word))
return plural2.Replace(word, "${keep}s");
else if (plural3.IsMatch(word))
return plural3.Replace(word, "${keep}es");
else if (plural4.IsMatch(word))
return plural4.Replace(word, "${keep}s");

return word;
}
}