将 IList 或 IEnumable 转换为 Array 的最佳方法

我有一个 HQL 查询，它既可以生成结果的 ILlist，也可以生成结果的 IEnumable。

然而，我希望它返回一个我选择的 Entity 的数组，实现这一点的最佳方法是什么？我可以枚举它并构建数组，也可以使用 CopyTo ()定义数组。

还有更好的办法吗? 我选择了复制方式。

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最佳答案

Which version of .NET are you using? If it's .NET 3.5, I'd just call ToArray() and be done with it.

If you only have a non-generic IEnumerable, do something like this:

IEnumerable query = ...;
MyEntityType[] array = query.Cast<MyEntityType>().ToArray();

If you don't know the type within that method but the method's callers do know it, make the method generic and try this:

public static void T[] PerformQuery<T>()
{
IEnumerable query = ...;
T[] array = query.Cast<T>().ToArray();
return array;
}
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Put the following in your .cs file:

using System.Linq;

You will then be able to use the following extension method from System.Linq.Enumerable:

public static TSource[] ToArray<TSource>(this System.Collections.Generic.IEnumerable<TSource> source)

I.e.

IEnumerable<object> query = ...;
object[] bob = query.ToArray();
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I feel like reinventing the wheel...

public static T[] ConvertToArray<T>(this IEnumerable<T> enumerable)
{
if (enumerable == null)
throw new ArgumentNullException("enumerable");


return enumerable as T[] ?? enumerable.ToArray();
}
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In case you don't have Linq, I solved it the following way:

    private T[] GetArray<T>(IList<T> iList) where T: new()
{
var result = new T[iList.Count];


iList.CopyTo(result, 0);


return result;
}

Hope it helps


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