在C＃中将值和键从一个字典复制到另一个字典的最快方法是什么？

There doesn't seem to be a dictionary.AddRange() method. Does anyone know a better way to copy the items to another dictionary without using a foreach loop.

似乎没有dictionary.AddRange()方法。有没有人知道在不使用foreach循环的情况下将项目复制到另一个字典的更好方法。

I'm using the System.Collections.Generic.Dictionary. This is for .NET 2.0.

我正在使用System.Collections.Generic.Dictionary。这适用于.NET 2.0。

6 个解决方案

#1

There's nothing wrong with a for/foreach loop. That's all a hypothetical AddRange method would do anyway.

for / foreach循环没有任何问题。无论如何,这都是假设的AddRange方法。

The only extra concern I'd have is with memory allocation behaviour, because adding a large number of entries could cause multiple reallocations and re-hashes. There's no way to increase the capacity of an existing Dictionary by a given amount. You might be better off allocating a new Dictionary with sufficient capacity for both current ones, but you'd still need a loop to load at least one of them.

我唯一需要关注的是内存分配行为,因为添加大量条目可能会导致多次重新分配和重新散列。没有办法按给定的数量增加现有词典的容量。你可能最好分配一个具有足够容量的新词典用于当前的词典,但你仍然需要一个循环来加载至少其中一个。

#2

There's the Dictionary constructor that takes another Dictionary.

还有Dictionary构造函数,它接受另一个Dictionary。

You'll have to cast it IDictionary, but there is an Add() overload that takes KeyValuePair<TKey, TValue>. You're still using foreach, though.

你必须将它转换为IDictionary,但是有一个Add()重载,它接受KeyValuePair 。不过,你还在使用foreach。 ,tvalue>

#3

var Animal = new Dictionary<string, string>();

one can pass existing animal Dictionary to the constructor.

可以将现有的动物词典传递给构造函数。

Dictionary<string, string> NewAnimals = new Dictionary<string, string>(Animal);

#4

For fun, I created this extension method to dictionary. This should do a deep copy wherever possible.

为了好玩,我创建了这个扩展方法到字典。这应该尽可能地进行深层复制。

public static Dictionary<TKey, TValue> DeepCopy<TKey,TValue>(this Dictionary&lt;TKey, TValue> dictionary)
        {
            Dictionary<TKey, TValue> d2 = new Dictionary<TKey, TValue>();

            bool keyIsCloneable = default(TKey) is ICloneable;
            bool valueIsCloneable = default(TValue) is ICloneable;

            foreach (KeyValuePair<TKey, TValue> kvp in dictionary)
            {
                TKey key = default(TKey);
                TValue value = default(TValue);
                if (keyIsCloneable)
                {
                    key = (TKey)((ICloneable)(kvp.Key)).Clone();
                }

                else
                {
                    key = kvp.Key;
                }

                if (valueIsCloneable)
                {
                    value = (TValue)((ICloneable)(kvp.Value)).Clone();
                }

                else
                {
                    value = kvp.Value;
                }

                d2.Add(key, value);
            }

            return d2;
        }

#5

If you're dealing with two existing objects, you might get some mileage with the CopyTo method: http://msdn.microsoft.com/en-us/library/cc645053.aspx

如果您正在处理两个现有对象,您可能会使用CopyTo方法获得一些里程:http://msdn.microsoft.com/en-us/library/cc645053.aspx

Use the Add method of the other collection (receiver) to absorb them.

使用其他集合(接收器)的Add方法吸收它们。

#6

I don't understand, why not using the Dictionary( Dictionary ) (as suggested by ageektrapped ).

我不明白,为什么不使用Dictionary(Dictionary)(由ageektrapped建议)。

Do you want to perform a Shallow Copy or a Deep Copy? (that is, both Dictionaries pointing to the same references or new copies of every object inside the new dictionary?)

您想要执行浅拷贝还是深拷贝? (也就是说,两个词典都指向相同的引用或新词典中每个对象的新副本?)

If you want to create a new Dictionary pointing to new objects, I think that the only way is through a foreach.

如果你想创建一个指向新对象的新词典,我认为唯一的方法是通过foreach。

#1