在字典C＃中排序

Question

我有一本字典

Dictionary<string, string> rList = new Dictionary<string, string>();
rList .Add("/a/b/c", "35");
rList .Add("/a/c/f/v", "25");
rList .Add("/a/r/d/c/r/v", "29");
rList .Add("/a", "21");
rList .Add("/a/f, "84");

我只想根據密鑰中存在的“/”數來對此字典進行排序。 我的預期出局是，

("/a/r/d/c/r/v", "29")
("/a/c/f/v", "25")
("/a/b/c", "35")
("/a/f, "84")
("/a", "21")

Answer 1

Dictionary<TKey, TValue>類型是.Net中的無序集合。 如果您想要訂購，那么您需要使用SortedDictionary<TKey, TValue>並提供自定義IComparer<string> ，它計算IComparer<string>的/值。

sealed class SlashComparer : IComparer<string> { 
  static int CountSlashes(string str) { 
    if (String.IsNullOrEmpty(str)) { 
      return 0;
    }

    int count = 0;
    for (int i = 0; i < str.Length; i++) {
      if (str[i] == '/') {
         count++;
      }
    }
    return count;
  }

  public int Compare(string left, string right) { 
    int leftCount = CountSlashes(left);
    int rightCount = CountSlashes(right);
    return rightCount - leftCount;
  }
}

要與SortedDictionary一起使用，您需要更改的唯一內容是聲明

var comparer = new SlashComparer();
var rList = new SortedDictionary<string, string>(comparer);

其余代碼可以保持不變

Answer 2

由於JaredPar已經回答了Dictionary<TKey, TValue>內容沒有指定順序。 但是，您可以按所需順序獲取List<KeyValuePair<TKey, TValue>> ：

List<KeyValuePair<string, string>> results = rList.OrderByDescending(x => x.Key.Count(c => c == '/')).ToList();

Answer 3

嘗試這個：

 var result = rList.OrderBy(input => input.Key.Select(c => c == '/').Count()).Reverse().ToList();

Answer 4

來自linqpad：

void Main()
{
    Dictionary<string, string> rList = new Dictionary<string, string>();
    rList .Add("/a/b/c", "35");
    rList .Add("/a/c/f/v", "25");
    rList .Add("/a/r/d/c/r/v", "29");
    rList .Add("/a", "21");
    rList .Add("/a/f", "84");

    var x = from a in rList
        let i = a.Key.ToCharArray().Count (k => k.Equals('/') )
        orderby i descending
        select a;

    x.Dump();
}