哈希集的浅表副本 [英] Shallow copy of a hashset

问题描述

做这件事的最好方法是什么?

Whats the best way of doing it?

var set2 = new HashSet<reference_type>();

用这样的foreach遍历集合.

Traverse the set with a foreach like this.

foreach (var n in set)
    set2.Add(n);

或者使用类似工会的东西.

Or use something like union like this.

set2 = set.UnionWith(set); // all the elements

推荐答案

使用构造函数:

HashSet<type> set2 = new HashSet<type>(set1);

我个人希望LINQ to Objects具有 ToHashSet 扩展方法，就像 List 和 Dictionary 一样.当然，创建自己的很容易:

Personally I wish LINQ to Objects had a ToHashSet extension method as it does for List and Dictionary. It's easy to create your own of course:

public static HashSet<T> ToHashSet<T>(this IEnumerable<T> source)
{
    if (source == null)
    {
        throw new ArgumentNullException("source");
    }
    return new HashSet<T>(source);
}

(对于自定义相等比较器，还有其他重载.)

(With an other overload for a custom equality comparer.)

这使得创建匿名类型的集合变得容易.

This makes it easy to create sets of an anonymous type.

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