如何在C＃中对对象类型进行强制转换？

Question

I have a:

public class MyClass { 
 private string PrivateString; 
}

and I have an interface that accepts:

object o

I have a list of MyClass that I need to push through object o, and my Google is failing me. What's the procedure to make this work? I know this must be crazy simple, but I've yet to do type casting in C#.

Answer 1

MyClass my = new MyClass();
WhateverTheFunctionThatTakesObjectIs(my);

Everything will implicitly cast to object.

Answer 2

The List<MyClass> object can still be just passed to your interface implementation, because List can be implicitly cast down to object (as can all objects). If the compiler complains because of the way you have your code set up (i have to say that because you haven't actually shown us any code) then you can explicitly cast it:

myInterfaceFunction((object) myList);

or:

myInterfaceFunction(myList as object);

If you want to cast the contents of the list and pass a List<object> when you already have a List<MyClass> then you can just do this:

myInterfaceFunction(myList.Cast<object>().ToList());

(you can get rid of the ToList() if your interface function uses IEnumerable<object> instead of List<object> ).

Here is a quick example. This has a good illustration of my comment about explicitly casting to object - by default the call to MyFunction(myList) will go to the MyFunction(IEnumerable<object> blah) function - you have to explicitly cast it to force it to go to the MyFunction(object blah) function.

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<MyObject> myList = new List<MyObject>();

            MyFunction(myList);
            MyFunction((object)myList);
            MyFunction(myList.Cast<object>().ToList());
            MyFunction(myList.Cast<object>());
        }


        public static void MyFunction(List<object> blah)
        {
            Console.WriteLine(blah.GetType().ToString());
        }

        public static void MyFunction(IEnumerable<object> blah)
        {
            Console.WriteLine(blah.GetType().ToString());
        }

        public static void MyFunction(object blah) 
        {
            Console.WriteLine(blah.GetType().ToString());
        }
    }


    public class MyObject { }
}

Answer 3

您不需要进行任何类型转换以将MyClass对象用于获取对象参数的方法，但是您可能在将MyClass对象列表转换为对象列表时遇到问题