/// <summary>
/// 获取两个字符串的相似度
/// </summary>
/// <param name=”sourceString”>第一个字符串</param>
/// <param name=”str”>第二个字符串</param>
/// <returns></returns>
public static decimal GetSimilarityWith(this string sourceString, string str)
{

decimal Kq = 2;
decimal Kr = 1;
decimal Ks = 1;

char[] ss = sourceString.ToCharArray();
char[] st = str.ToCharArray();

//获取交集数量
int q = ss.Intersect(st).Count();
int s = ss.Length – q;
int r = st.Length – q;

return Kq * q / (Kq * q + Kr * r + Ks * s);
}

------解决方案--------------------
C#实现字符串相似度比较[Levenshtein Distance算法]