对winform的TextBox，如何以覆盖(overwrite)而不是插入的方式更新其内容？

Question

RT

Answer 1

在keypress事件中
txtbox.SelectionLength= 1;

Answer 2

晕~~~~~~~~~
这个也可以
写前清空文本框
或者直接 Text=
保证世界清净了

Answer 3

using  System;  
http://www.faq-it.org/apache/">faq-it.org/apache/ using  System.Drawing;  
using  System.Collections;  
using  System.ComponentModel;  
using  System.Windows.Forms;  
 
namespace  Cmic.Controls  
{  
           ///  <summary>  
           ///  TextBoxEx  的摘要说明。  
           ///  </summary>  
           public  class  TextBoxInsert  :  System.Windows.Forms.TextBox  
           {  
                       ///  <summary>  
                       ///  必需的设计器变量。  
                       ///  </summary>  
                       private  System.ComponentModel.Container  components  =  null;  
                       enum  TypeMode{InsertMode,  OvertypeMode};  
                       private  TypeMode  typeMode;  
 
                       public  TextBoxInsert()  
                       {  
                                   //  
                                   //  Windows  窗体设计器支持所必需的  
                                   //  
                                   InitializeComponent();  
                                   this.typeMode  =  TypeMode.InsertMode;  
                                     
 
                                   //  
                                   //  TODO:  在  InitializeComponent  调用后添加任何构造函数代码  
                                   //  
                       }  
 
                       ///  <summary>  
                       ///  清理所有正在使用的资源。  
                       ///  </summary>  
                       protected  override  void  Dispose(  bool  disposing  )  
                       {  
                                   if(  disposing  )  
                                   {  
                                               if(components  !=  null)  
                                               {  
                                                           components.Dispose();  
                                               }  
                                   }  
                                   base.Dispose(  disposing  );  
                       }  
 
                       #region  Windows  窗体设计器生成的代码  
                       ///  <summary>  
                       ///  设计器支持所需的方法  -  不要使用代码编辑器修改  
                       ///  此方法的内容。  
                       ///  </summary>  
                       private  void  InitializeComponent()  
                       {  
                                   //    
                                   //  TextBoxInsert  
                                   //    
                                   this.Text  =  "TextBoxEx";  
 
                       }  
                       #endregion  
                       protected  override  void  OnTextChanged(EventArgs  e)  
                       {  
                                   base.OnTextChanged  (e);  
//                                    if(this.typeMode  ==  TypeMode.InsertMode  &&  this.SelectionLength  ==  0)  
//                                    {  
//                                                this.SelectionLength  =  1;  
//                                    }  
                                   if(this.typeMode==  TypeMode.OvertypeMode)  
                                   {  
                                               this.SelectionLength  =  1;  
                                   }  
                       }  
                       protected  override  void  OnKeyPress(KeyPressEventArgs  e)  
                       {  
                                   base.OnKeyPress  (e);  
                                   if((e.KeyChar  ==  (char)8)  &&  (typeMode  ==  TypeMode.OvertypeMode))  
                                   {  
                                               this.SelectionLength  =  0;  
                                   }  
                       }  
                       protected  override  void  OnKeyDown(KeyEventArgs  e)  
                       {  
                                   base.OnKeyDown(e);    
                                   switch(e.KeyCode)  
                                   {  
                                               case  Keys.Insert:  
                                                           if(this.typeMode  ==  TypeMode.OvertypeMode)  
                                                           {  
                                                                       this.typeMode  =  TypeMode.InsertMode;  
                                                           }  
                                                           else  
                                                           {  
                                                                       this.SelectionLength  =  1;  
                                                                       this.typeMode  =  TypeMode.OvertypeMode;  
                                                           }  
                                                           break;  
 
                                               case  Keys.Left:  
                                                           if(this.typeMode  ==  TypeMode.OvertypeMode)  
                                                           {    
                                                                       e.Handled=true;  
                                                                       if(this.SelectionStart!=0)  
                                                                       {  
                                                                                   this.SelectionStart=this.SelectionStart-1;  
                                                                                   this.SelectionLength=1;                
                                                                       }  
                                                           }  
                                                           break;  
                                               case  Keys.Right:  
                                                           if(this.typeMode  ==  TypeMode.OvertypeMode)  
                                                           {  
                                                                       e.Handled=true;  
                                                                       if(this.SelectionStart!=this.Text.Length)  
                                                                       {  
                                                                                   this.SelectionStart=this.SelectionStart+1;  
                                                                                   this.SelectionLength=1;    
                                                                       }  
                                                           }  
                                                           break;  
                                               default:  
                                                           break;  
                                   }  
                       }  
           }  
}
http://www.faq-it.org/archives/csharp/f33832690ae4b722c81c6f2569fc0b03.php