类型转换文本框 [英] Type Casting TextBox

问题描述

大家好，


我在C#中进行了abt转换，下面让我解释一下.

我有第三方类，该类返回System.Window.Form.Textbox.


我想将此TextBox分配给My custom textbox Class.

以下是我的自定义课程的示例

Hi all ,


I have dout abt casting in C# let me explain .

I have third party class which return a System.Window.Form.Textbox.


I want to assign this TextBox to My custom textbox Class .

Below is the Eg of my Custom Class

public class TestTextbox : TextBox
 {
     public override Font Font { get { return base.Font; } set { base.Font = value; } }

 }

但我无法投射此

but i m not able to cast this

TestTextbox txt = (TestTextbox)(Some method Which returns System.Window.Form.Textbox );

我缺少什么，


在此先感谢.

What im missing ,


Thanks in Advance.

推荐答案

您是从TextBox派生的.结果，您不能强制将父级强制转换为子级.
这段代码根本行不通.

你不能垂头丧气. TestTextBox 将具有一些TextBox 可能没有的其他方法.
结果，如果您能够向下转换，则这些方法将不可用.

You are deriving from TextBox. As a result, you cannot force a cast of a parent into a child class.
This code simply won''t work.

You cannot downcast. TestTextBox will have some additional methods which TextBox may not have.
As a result, if you were able to downcast, those methods would not be available.

您好，

请尝试，

Hi,

Please try,

TestTextbox txt =(method Which returns System.Window.Form.Textbox) as  TestTextbox;

希望这会有所帮助.

Hope this helps.

这篇关于类型转换文本框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！