比较 2 个 Dictionary<string, string> 实例

Question

我想比较两个Dictionary<string, string> 实例的内容，而不管它们包含的项目的顺序如何。 SequenceEquals 也比较顺序，所以我先按键排序字典，然后调用SequenceEquals。

有什么方法可以代替SequenceEquals 只比较内容吗？

如果没有，这是理想的方法吗？

Dictionary<string, string> source = new Dictionary<string, string>();
Dictionary<string, string> target = new Dictionary<string, string>();

source["foo"] = "bar";
source["baz"] = "zed";
source["blah"] = null;

target["baz"] = "zed";
target["blah"] = null;
target["foo"] = "bar";

// sequenceEquals will be false
var sequenceEqual = source.SequenceEqual(target);
// contentsEqual will be true
var contentsEqual = source.OrderBy(x => x.Key).SequenceEqual(target.OrderBy(x => x.Key));

Answer 1

var contentsEqual = source.DictionaryEqual(target);

// ...

public static bool DictionaryEqual<TKey, TValue>(
    this IDictionary<TKey, TValue> first, IDictionary<TKey, TValue> second)
{
    return first.DictionaryEqual(second, null);
}

public static bool DictionaryEqual<TKey, TValue>(
    this IDictionary<TKey, TValue> first, IDictionary<TKey, TValue> second,
    IEqualityComparer<TValue> valueComparer)
{
    if (first == second) return true;
    if ((first == null) || (second == null)) return false;
    if (first.Count != second.Count) return false;

    valueComparer = valueComparer ?? EqualityComparer<TValue>.Default;

    foreach (var kvp in first)
    {
        TValue secondValue;
        if (!second.TryGetValue(kvp.Key, out secondValue)) return false;
        if (!valueComparer.Equals(kvp.Value, secondValue)) return false;
    }
    return true;
}

Answer 2

我不知道是否存在现有方法，但您可以使用以下方法（为简洁起见，省略了对 args 的空检查）

public static bool DictionaryEquals<TKey,TValue>(
  this Dictionary<TKey,TValue> left,
  Dictionary<TKey,TValue> right ) { 

  var comp = EqualityComparer<TValue>.Default;
  if ( left.Count != right.Count ) { 
    return false;
  }
  foreach ( var pair in left ) {
    TValue value;
    if ( !right.TryGetValue(pair.Key, out value) 
         || !comp.Equals(pair.Value, value) ) {
      return false;
    }
  } 
  return true;
}

最好添加一个重载以允许自定义EqualityComparer<TValue>。

Answer 3

如果您使用SortedDictionary，则无需自行应用排序，使用起来会稍微容易一些：

void Main()
{
    var d1 = new Dictionary<string, string>
    {
        ["a"] = "Hi there!",
        ["b"] = "asd",
        ["c"] = "def"
    };
    var d2 = new Dictionary<string, string>
    {
        ["b"] = "asd",
        ["a"] = "Hi there!",
        ["c"] = "def"
    };

    var sortedDictionary1 = new SortedDictionary<string, string>(d1);
    var sortedDictionary2 = new SortedDictionary<string, string>(d2);

    if (sortedDictionary1.SequenceEqual(sortedDictionary2))
    {
        Console.WriteLine("Match!");
    }
    else
    {
        Console.WriteLine("Not match!");
    }
}

Answer 4

这将检查source中的所有Values是否存在于target中，忽略Keys

var result = source.All(x => target.Any(y => x.Value == y.Value));