如何将类型转换为类型名称？ [英] How do I cast a type to a typename?

问题描述

假设我有一个带有通用参数的方法，我该如何输入：

Say I have a method with generic parameters, how do I enter:

doSomething<foo.GetType()>();

为什么这不起作用？如何使这项工作？

Why doesn't this work and how can I make this work?

推荐答案

As我知道， foo.GetType（）是在运行时调用的，所以你应该尝试使用 typeof（foo）在编译时管理。

As I know, foo.GetType() is invoked at runtime, so you should try by using typeof(foo) that is managed at compile time.

为什么？简单：因为你没有参数，所以在编译时决定调用你的方法的类型 - 不能从用法中推断出类型。这意味着你必须提供一个常量类型说明符，而不是方法调用。



相反，试试这个：

Why? Simple: because you have no parameters, the decision as to what type to call your method with is decided at compile time - the type cannot be inferred from the usage. Which mean you have to provide a constant type specifier, rather than a method call.

Instead, try this:

private void DoSomething<T>()
    {
    Console.WriteLine("DoSomething:" + typeof(T));
    }
private void DoSomething<T>(T x)
    {
    Console.WriteLine("DoSomething:" + x.GetType());
    }

然后你可以调用它：

Then you can call it:

DoSomething<int>();
DoSomething<float>();
double d = 12.34;
DoSomething(d);

得到你想要的东西：

And get what you want:

DoSomething:System.Int32
DoSomething:System.Single
DoSomething:System.Double

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