在.NET中,字典[duplicate]是否存在键冲突

您可以轻松生成此类碰撞(请参见 https://en.wikipedia.org/wiki/Birthday_problem ),例如。

  // key   - computed hash value
  // value - original string
  Dictionary<int, string> hashes = new Dictionary<int, string>();

  for (int i = 0; ; ++i) {
    string st = i.ToString();
    int hash = st.GetHashCode();
    string collision = null;

    if (hashes.TryGetValue(hash, out collision)) {
      Console.Write($"Collision: \"{collision}\" and \"{st}\" hash {hash}");

      break;
    }
    else
      hashes.Add(hash, st);
  }

结果(在我的工作站.Net 4.6.1 x86上):

  Collision: "699391" and "1241308" hash -1612916492

  Collision: "942" and "9331582" hash -1864841629

因此,如果您想看到键冲突(在x86模式下):

 // Both "699391" and "1241308" keys have the same hash -1612916492
 Dictionary<string, string> demo = new Dictionary<string, string>() {
   {"699391", "abc"},
   {"1241308", "def"},
 };

最后 String.GetHashCode 是 内部加工 可以依赖