下面是我使用的一个helper函数:

using System.Collections.Generic;
namespace HelperMethods
{
    public static class MergeDictionaries
    {
        public static void Merge<TKey, TValue>(this IDictionary<TKey, TValue> first, IDictionary<TKey, TValue> second)
        {
            if (second == null || first == null) return;
            foreach (var item in second) 
                if (!first.ContainsKey(item.Key)) 
                    first.Add(item.Key, item.Value);
        }
    }
}

Dictionary<String, String> allTables = new Dictionary<String, String>();
allTables = tables1.Union(tables2).ToDictionary(pair => pair.Key, pair => pair.Value);

试试

namespace Extensions
{
    public static class DictionaryExtensions
    {
        public static Dictionary<T, Y> MergeWith<T, Y>(this Dictionary<T, Y> dictA,
            Dictionary<T, Y> dictB)
        {
            foreach (var item in dictB)
            {
                if (dictA.ContainsKey(item.Key))
                    dictA[item.Key] = item.Value;
                else
                    dictA.Add(item.Key, item.Value);
            }
            return dictA;
        }
    }
}

当你想合并两个字典时

    var d1 = new Dictionary<string, string>();
    var d2 = new Dictionary<string, string>();
    d1.MergeWith(d2);

public static IDictionary<K, V> AddRange<K, V>(this IDictionary<K, V> one, IDictionary<K, V> two)
        {
            foreach (var kvp in two)
            {
                if (one.ContainsKey(kvp.Key))
                    one[kvp.Key] = two[kvp.Key];
                else
                    one.Add(kvp.Key, kvp.Value);
            }
            return one;
        }

使用equalitycompararer进行合并，它将项目映射到不同的值/类型进行比较。这里我们将从KeyValuePair(枚举字典时的项类型)映射到Key。

public class MappedEqualityComparer<T,U> : EqualityComparer<T>
{
    Func<T,U> _map;

    public MappedEqualityComparer(Func<T,U> map)
    {
        _map = map;
    }

    public override bool Equals(T x, T y)
    {
        return EqualityComparer<U>.Default.Equals(_map(x), _map(y));
    }

    public override int GetHashCode(T obj)
    {
        return _map(obj).GetHashCode();
    }
}

用法:

// if dictA and dictB are of type Dictionary<int,string>
var dict = dictA.Concat(dictB)
                .Distinct(new MappedEqualityComparer<KeyValuePair<int,string>,int>(item => item.Key))
                .ToDictionary(item => item.Key, item=> item.Value);

如何添加一个参数重载?

此外，您应该将它们输入为dictionary以获得最大的灵活性。

public static IDictionary<TKey, TValue> Merge<TKey, TValue>(IEnumerable<IDictionary<TKey, TValue>> dictionaries)
{
    // ...
}

public static IDictionary<TKey, TValue> Merge<TKey, TValue>(params IDictionary<TKey, TValue>[] dictionaries)
{
    return Merge((IEnumerable<TKey, TValue>) dictionaries);
}