C#中的继承问题. [英] Problem with inheritance in C#.

问题描述

我对C#继承有一点问题.很简单，但我想不起来！
假设我有一个父类和一个子类(child:parent).
我只想知道是否定义(子代=新父代)可以访问子代属性?因为我尝试过，但是我做不到，顺便说一句，我认为它应该可以工作..

这是一个示例代码:

I have a little problem with C# inheritance. It''s easy but I cant figure it out!
Suppose I have a parent class and a child class(child:parent).
I just want to know if we define (child = new parent) can we access to child properties? Because I tried it but I couldn''t do that, by the way i think it should work..

Here is a example code:

public class Parent
    {
        private int _Parent1;

        public int Parent1
        {
            get { return _Parent1; }
            set { _Parent1 = value; }
        }   
    }

public class Child1 : Parent
    {
        private int _Child1Prop;

        public int Child1Prop
        {
            get { return _Child1Prop; }
            set { _Child1Prop = value; }
        }
    }

假设

suppose

Parent test = new Child1();

这可能吗?

Is this possible:?

test.Child1Prop = some value;

推荐答案

您无法编写

You cannot write

Child=new Parent;

编译器会 d抱怨.

The compiler would complain.

[已更新]

好的，您现在改写了这个问题:

[updated]

OK, you rephrased the question, now:

Parent test = new Child1();
test.Child1Prop = some value;

不可能是不可能的.

但是，例如:

is not possible.

However, for instance:

Parent parent = new Child1();
(parent as Child1).Child1Prop = 5;

会很好.

[/update]

would work fine.

[/update]

这不可能:

This isn''t possible:

child1 test = new Parent;

您不能将基础强制转换为子对象.根据我的经验，这是不可能的.您可以像这样在Child1类中实现构造函数:

You can''t cast base to the child object. From my experience this isn''t possible. You can implement constructor in Child1 class like this:

public Child1(Parent parent)
{
   _Child1Prop = 2;
}

但是您可以执行以下操作:

BUT you can do something like this:

    public class Parent
    {
    }

    public class Child1 : Parent
    {
    }

    public class Child2 : Child1
    {
    }

    public class Child3 : Child2
    {
    }

//-------------- somewhere in Main -------
    Child3 ch3 = new Child3();
    Child1 ch1 = (Child1)ch3;
    Child2 ch2 = (Child2)ch1;

希望您能这样问.

I hope you''re asked this.

child1 test = new Parent;

根本不可能.

您的解决方案有效，但我不想使用转换！！"

不管有没有强制转换，都无法做这样的事情.

您可以执行以下操作:

simply this isn''t possible.

"your solution works but i dont want to use casting!!!"

There is no way to do something like that with or without casting, it''s not allowed.

You can do this:

public class Child1 : Parent
{
    public static implicit operator Child2(Child1 ch2)
    {
        return new Child2();
    }
}

public class Child2 : Child1
{
    Child2 ch2 = new Child1();
}

但在这种情况下不是:

but not in this case:

child1 test = new Parent;

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