在C#中使用OfType过滤类型的对象 [英] Filtering the object of a type with OfType in C#

问题描述

我有一个基类Base和一个继承自它的类A/B.

I have a base class Base, and class A/B that inherits from it.

public class Base
{
    int x;
}
public class A : Base
{
    int y;
}
public class B : Base
{
    int z;
}

我试图使用OfType过滤我唯一需要的对象，如下所示:

I tried to use OfType to filter the only object that I need as follows:

public static void RunSnippet()
{
    Base xbase; A a; B b;
    IEnumerable<Base> list = new List<Base>() {xbase, a, b};
    Base f = list.OfType<A>; // I need to get only the object A
    Console.WriteLine(f);
}

编译代码时，出现此错误:

When I compiled the code, I got this error:

错误CS0428:无法将方法组'OfType'转换为非委托类型'Base'.你打算吗 调用该方法?

error CS0428: Cannot convert method group 'OfType' to non-delegate type 'Base'. Did you intend to invoke the method?

代码有什么问题?

推荐答案

有两个问题:

• OfType返回IEnumerable<T>，而不是T
• 这是一种方法-您忘记了括号

• OfType returns IEnumerable<T>, not T
• It's a method - you forgot the brackets

也许您想要:

Base f = list.OfType<A>().FirstOrDefault();

?

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