具有相同名称和签名，但在C＃中的返回类型的方法 [英] Method with same name and signature but return type in C#
问题描述
我有一次采访中，我被问了以下内容：
I had an interview where I was asked the following:
问：具有相同名称和签名，但不同的返回类型的方法。是否有可能的，什么是所谓的这种类型的，他问我。
Question: A method with same name and signature but different return type. Is it possible and what is this type called he asked me.
有人能告诉我下面的：
-
是上面的事情可能在任何情况下（像之一的基类，一个在派生类中ATLEAST？）如果是的话是什么类型呢？像编译或运行时多态性？
Is above thing possible in any scenarios (Like one in base class and one in derived class atleast ?) If so what type is it ? Like compile or runtime polymorphism ?
在编译时多态，如果有什么方法的返回类型也各不相同与签名一起去吗？但功能只有名称相同。难道还要编译时多态？
In compile time polymorphism, what if the return types of methods are also different along with signature ? But only the name of function is same. Is it compile time polymorphism still ?
在压倒一切，如果我有不同的返回类型，但方法名和签名都是一样的吗？可能吗 ？ （他问我这个问题，我回答错误的:(）请大家帮帮我。
In overriding, what if I have different return type but the method name and signature are same ? Is it possible ? (He asked me this question, I answered wronglY :() Please help me.
感谢您
推荐答案
它允许一个方法返回一个更衍生型比基本型，例如宣布一个
It allows a method to return a more-derived type than the one declared in a base type e.g.
public interface ISomeInterface
{
object GetValue();
}
public class SomeClass : ISomeInterface
{
public string GetValue() { return "Hello world"; }
}
这是支持Java的，但不是在C＃。上述自 SomeClass.GetValue 的返回类型将不会编译为字符串不是对象。
This is supported in Java but not in C#. The above will not compile since the return type of SomeClass.GetValue is string not object.
请注意，基于收益型，即单纯的跟着你不能重载的方法是无效的：
Note that you cannot overload methods based on return-type alone i.e. the following is not valid:
public class SomeClass
{
public int GetValue() { return 1; }
public string GetValue() { return "abc"; }
}
您可以做类似的东西使用接口虽然你需要明确地实现它们进行区分：
You could do something similar using interfaces although you would need to implement them explicitly to disambiguate:
public interface IValue<T> { T GetValue(); }
public class SomeClass : IValue<int>, IValue<string>
{
string IValue<string>.GetValue() { return "abc"; }
int IValue<int>.GetValue() { return 1; }
}
如果名字是相同的，但参数不同，那么这是方法过载。这是多态性（特设多态性）的一种形式。重载是在编译型静态解析（除非你使用动态在这种情况下，他们被推迟到运行时）。
If the names are the same but the parameters are different then this is method overloading. This is a form of polymorphism (ad-hoc polymorphism). Overloads are resolved statically at compile-type (unless you're using dynamic in which case they are deferred to run-time).
可以对参数的数目和它们的类型超载，所以下面都是有效的：
You can overload on both the number of parameters and their type, so the following are all valid:
public void DoSomething(int value) { }
public void DoSomething(string value) { }
public void DoSomething(int value, string value) { }
请注意，你可以改变这些方法的返回类型 - 方法不仅可以根据自己的收益单独类型，但它们可以是不同的，如果他们的参数列表是不同的过载。
Note that you can vary the return type of these methods - methods cannot only be overloaded based on their return type alone but they can differ if their parameter lists are different.
再次，这是返回类型的协方差，不支持在C＃。
Again this is return type covariance and is not supported in C#.
这篇关于具有相同名称和签名，但在C＃中的返回类型的方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
