Private Sub AddHandlers()
    ' Add the Validating and Validated handlers for textboxes.
    AddHandler myTextBox1.Validating, AddressOf myTextBox1_Validating
    AddHandler myTextBox1.Validated, AddressOf myTextBox1_Validated
    AddHandler myTextBox2.Validating, AddressOf myTextBox2_Validating
    AddHandler myTextBox2.Validated, AddressOf myTextBox2_Validated
    AddHandler myTextBox1.CausesValidationChanged, AddressOf myTextBox1_CausesValidationChanged
    AddHandler myTextBox2.CausesValidationChanged, AddressOf myTextBox2_CausesValidationChanged
    If myTextBox1.CausesValidation = True And myTextBox2.CausesValidation = True Then
       button1.Text = "Disable Validation"
       myLabel.Text = "Validation Enabled"
       Me.Focus()
    End If
End Sub 'AddHandlers
 
Private Sub myTextBox1_Validating(sender As Object, e As System.ComponentModel.CancelEventArgs)
    If Not CheckIfTextBoxNumeric(myTextBox1) Then
       myLabel.Text = "Has to be numeric"
       e.Cancel = True
    End If
End Sub 'myTextBox1_Validating
 
Private Sub myTextBox1_Validated(sender As Object, e As System.EventArgs)
    myLabel.Text = "Validated first control"
End Sub 'myTextBox1_Validated
 
Private Sub myTextBox2_Validating(sender As Object, e As System.ComponentModel.CancelEventArgs)
    If Not CheckIfTextBoxNumeric(myTextBox2) Then
       myLabel.Text = "Has to be numeric"
       e.Cancel = True
    End If
End Sub 'myTextBox2_Validating
 
Private Sub myTextBox2_Validated(sender As Object, e As System.EventArgs)
    myLabel.Text = "Validated second control"
End Sub 'myTextBox2_Validated
 
Private Sub myTextBox1_CausesValidationChanged(sender As Object, e As System.EventArgs)
    myLabel.Text = "CausesValidation property was changed for First Textbox"
End Sub 'myTextBox1_CausesValidationChanged
 
Private Sub myTextBox2_CausesValidationChanged(sender As Object, e As System.EventArgs)
    myLabel.Text = "CausesValidation property was changed for Second Textbox"
End Sub 'myTextBox2_CausesValidationChanged
 
Private Function CheckIfTextBoxNumeric(myTextBox1 As TextBox) As Boolean
    Dim isValid As Boolean = True
    If myTextBox1.Text = "" Then
       isValid = False
    Else
       Dim i As Integer
       For i = 0 To myTextBox1.Text.Length - 1
          If Not IsNumeric(myTextBox1.Text) Then
             myTextBox1.Text = ""
             isValid = False
             Exit For
          End If
       Next i
    End If
    Return isValid
End Function 'CheckIfTextBoxNumeric
 
Private Sub myButtonAdd_Click(sender As Object, e As System.EventArgs) Handles myButtonAdd.Click
   Try
      Dim result As Integer = Convert.ToInt32(myTextBox1.Text) + Convert.ToInt32(myTextBox2.Text)
       myLabel.Text = result.ToString()
    Catch myException As Exception
       myLabel.Text = "Exception : " + myException.Message
    End Try
End Sub 'myButtonAdd_Click
 
 
Private Sub button1_Click(sender As Object, e As System.EventArgs) Handles button1.Click
    If myTextBox1.CausesValidation = False And myTextBox2.CausesValidation = False Then
       myTextBox1.CausesValidation = True
       myTextBox2.CausesValidation = True
       button1.Text = "Disable Validation"
       myLabel.Text = "Validation Enabled"
    Else
       If myTextBox1.CausesValidation = True And myTextBox2.CausesValidation = True Then
          myTextBox1.CausesValidation = False
          myTextBox2.CausesValidation = False
          button1.Text = "Enable Validation"
          myLabel.Text = "Validation Disabled"
       End If
    End If
End Sub 'button1_Click 

private void AddHandlers()
{
   // Add the Validating and Validated handlers for textboxes.
   myTextBox1.Validating +=
      new System.ComponentModel.CancelEventHandler(myTextBox1_Validating);
   myTextBox1.Validated += 
      new System.EventHandler(myTextBox1_Validated);
   myTextBox2.Validating += 
      new System.ComponentModel.CancelEventHandler(myTextBox2_Validating);
   myTextBox2.Validated += 
      new System.EventHandler(myTextBox2_Validated);
   myTextBox1.CausesValidationChanged += 
      new System.EventHandler(myTextBox1_CausesValidationChanged);
   myTextBox2.CausesValidationChanged += 
      new System.EventHandler(myTextBox2_CausesValidationChanged);
   if(myTextBox1.CausesValidation == true && myTextBox2.CausesValidation == true) 
   {
      button1.Text = "Disable Validation";
      myLabel.Text = "Validation Enabled"; 
      this.Focus(); 
   }
}
private void myTextBox1_Validating(object sender,System.ComponentModel.CancelEventArgs e)
{        
   if(!CheckIfTextBoxNumeric(myTextBox1))
   {
      myLabel.Text =  "Has to be numeric";
      e.Cancel = true;
   }
}
private void myTextBox1_Validated(object sender,System.EventArgs e)
{
   myLabel.Text = "Validated first control";          
}
private void myTextBox2_Validating(object sender,System.ComponentModel.CancelEventArgs e)
{
   if(!CheckIfTextBoxNumeric(myTextBox2))
   {
      myLabel.Text =  "Has to be numeric";
      e.Cancel = true;
   }
}
private void myTextBox2_Validated(object sender,System.EventArgs e)
{
   myLabel.Text = "Validated second control";
}
private void myTextBox1_CausesValidationChanged(object sender,System.EventArgs e)
{  
   myLabel.Text = "CausesValidation property was changed for First Textbox";
}
private void myTextBox2_CausesValidationChanged(object sender,System.EventArgs e)
{  
   myLabel.Text = "CausesValidation property was changed for Second Textbox";
}
private bool CheckIfTextBoxNumeric(TextBox myTextBox1)
{ 
   bool isValid = true;
   if(myTextBox1.Text == "")
   {
      isValid = false;
   }
   else
   {
      for(int i=0; i< myTextBox1.Text.Length;i++)
      {
         if(!(System.Char.IsNumber(myTextBox1.Text[i]))) 
         {
            myTextBox1.Text = ""; 
            isValid = false;
            break;
         }
      }
   }
   return isValid;
}
private void myButtonAdd_Click(object sender, System.EventArgs e)
{  
   try
   {
      int result = Convert.ToInt32(myTextBox1.Text) + Convert.ToInt32(myTextBox2.Text);
      myLabel.Text =  result.ToString();
   }
   catch(Exception myException)
   {
      myLabel.Text = "Exception : " + myException.Message;
   }
}

private void button1_Click(object sender, System.EventArgs e)
{  
   if(myTextBox1.CausesValidation == false && myTextBox2.CausesValidation == false) 
   {
      myTextBox1.CausesValidation = true;
      myTextBox2.CausesValidation = true;
      button1.Text = "Disable Validation"; 
      myLabel.Text = "Validation Enabled"; 
   }
   else if(myTextBox1.CausesValidation == true && myTextBox2.CausesValidation == true) 
   {
      myTextBox1.CausesValidation = false;
      myTextBox2.CausesValidation = false;
      button1.Text = "Enable Validation"; 
      myLabel.Text = "Validation Disabled"; 
   }
}

private:
   void AddHandlers()
   {
      
      // Add the Validating and Validated handlers for textboxes.
      myTextBox1->Validating += gcnew System::ComponentModel::CancelEventHandler( this, &Form1::myTextBox1_Validating );
      myTextBox1->Validated += gcnew System::EventHandler( this, &Form1::myTextBox1_Validated );
      myTextBox2->Validating += gcnew System::ComponentModel::CancelEventHandler( this, &Form1::myTextBox2_Validating );
      myTextBox2->Validated += gcnew System::EventHandler( this, &Form1::myTextBox2_Validated );
      myTextBox1->CausesValidationChanged += gcnew System::EventHandler( this, &Form1::myTextBox1_CausesValidationChanged );
      myTextBox2->CausesValidationChanged += gcnew System::EventHandler( this, &Form1::myTextBox2_CausesValidationChanged );
      if ( myTextBox1->CausesValidation == true && myTextBox2->CausesValidation == true )
      {
         button1->Text = "Disable Validation";
         myLabel->Text = "Validation Enabled";
         this->Focus();
      }
   }

   void myTextBox1_Validating( Object^ /*sender*/, System::ComponentModel::CancelEventArgs^ e )
   {
      if (  !CheckIfTextBoxNumeric( myTextBox1 ) )
      {
         myLabel->Text = "Has to be numeric";
         e->Cancel = true;
      }
   }

   void myTextBox1_Validated( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      myLabel->Text = "Validated first control";
   }

   void myTextBox2_Validating( Object^ /*sender*/, System::ComponentModel::CancelEventArgs^ e )
   {
      if (  !CheckIfTextBoxNumeric( myTextBox2 ) )
      {
         myLabel->Text = "Has to be numeric";
         e->Cancel = true;
      }
   }

   void myTextBox2_Validated( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      myLabel->Text = "Validated second control";
   }

   void myTextBox1_CausesValidationChanged( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      myLabel->Text = "CausesValidation property was changed for First Textbox";
   }

   void myTextBox2_CausesValidationChanged( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      myLabel->Text = "CausesValidation property was changed for Second Textbox";
   }

   bool CheckIfTextBoxNumeric( TextBox^ myTextBox1 )
   {
      bool isValid = true;
      if ( myTextBox1->Text->Equals( "" ) )
      {
         isValid = false;
      }
      else
      {
         for ( int i = 0; i < myTextBox1->Text->Length; i++ )
         {
            if (  !(System::Char::IsNumber( myTextBox1->Text[ i ] )) )
            {
               myTextBox1->Text = "";
               isValid = false;
               break;
            }

         }
      }

      return isValid;
   }

   void myButtonAdd_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      try
      {
         int result = Convert::ToInt32( myTextBox1->Text ) + Convert::ToInt32( myTextBox2->Text );
         myLabel->Text = result.ToString();
      }
      catch ( Exception^ myException ) 
      {
         myLabel->Text = "Exception : ",myException->Message;
      }

   }

   void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      if ( myTextBox1->CausesValidation == false && myTextBox2->CausesValidation == false )
      {
         myTextBox1->CausesValidation = true;
         myTextBox2->CausesValidation = true;
         button1->Text = "Disable Validation";
         myLabel->Text = "Validation Enabled";
      }
      else
      if ( myTextBox1->CausesValidation == true && myTextBox2->CausesValidation == true )
      {
         myTextBox1->CausesValidation = false;
         myTextBox2->CausesValidation = false;
         button1->Text = "Enable Validation";
         myLabel->Text = "Validation Disabled";
      }
   }

private void AddHandlers()
{
    // Add the Validating and Validated handlers for textboxes.
    myTextBox1.add_Validating(new System.ComponentModel.
        CancelEventHandler(myTextBox1_Validating));
    myTextBox1.add_Validated(new System.EventHandler(myTextBox1_Validated));
    myTextBox2.add_Validating(new System.ComponentModel.
        CancelEventHandler(myTextBox2_Validating));
    myTextBox2.add_Validated(new System.EventHandler(myTextBox2_Validated));
    myTextBox1.add_CausesValidationChanged(new System.
        EventHandler(myTextBox1_CausesValidationChanged));
    myTextBox2.add_CausesValidationChanged(new System.
        EventHandler(myTextBox2_CausesValidationChanged));
    if (myTextBox1.get_CausesValidation() == true && myTextBox2.
        get_CausesValidation() == true) {
        button1.set_Text("Disable Validation");
        myLabel.set_Text("Validation Enabled");
        this.Focus();
    }
} //AddHandlers

private void myTextBox1_Validating(Object sender, 
    System.ComponentModel.CancelEventArgs e)
{
    if (!(CheckIfTextBoxNumeric(myTextBox1))) {
        myLabel.set_Text("Has to be numeric");
        e.set_Cancel(true);
    }
} //myTextBox1_Validating

private void myTextBox1_Validated(Object sender, 
    System.EventArgs e)
{
    myLabel.set_Text("Validated first control");
} //myTextBox1_Validated

private void myTextBox2_Validating(Object sender, 
    System.ComponentModel.CancelEventArgs e)
{
    if (!(CheckIfTextBoxNumeric(myTextBox2))) {
        myLabel.set_Text("Has to be numeric");
        e.set_Cancel(true);
    }
} //myTextBox2_Validating

private void myTextBox2_Validated(Object sender, System.EventArgs e)
{
    myLabel.set_Text("Validated second control");
} //myTextBox2_Validated

private void myTextBox1_CausesValidationChanged(Object sender, 
    System.EventArgs e)
{
    myLabel.set_Text("CausesValidation property was changed for "
        + "First Textbox");
} //myTextBox1_CausesValidationChanged

private void myTextBox2_CausesValidationChanged(Object sender, 
    System.EventArgs e)
{
    myLabel.set_Text("CausesValidation property was changed for "
        + "Second Textbox");
} //myTextBox2_CausesValidationChanged

private boolean CheckIfTextBoxNumeric(TextBox myTextBox1)
{
    boolean isValid = true;
    if (myTextBox1.get_Text().Equals("")) {
        isValid = false;
    }
    else {
        for (int i = 0; i < myTextBox1.get_Text().get_Length(); i++) {
            if (!(System.Char.IsNumber(myTextBox1.get_Text().
                get_Chars(i)))) {
                myTextBox1.set_Text("");
                isValid = false;
                break;
            }
        }
    }
    return isValid;
} //CheckIfTextBoxNumeric

private void myButtonAdd_Click(Object sender, System.EventArgs e)
{
    try {
        int result = Convert.ToInt32(myTextBox1.get_Text()) 
            + Convert.ToInt32(myTextBox2.get_Text());
        myLabel.set_Text(System.Convert.ToString(result));
    }
    catch (System.Exception myException) {
        myLabel.set_Text("Exception : " + myException.get_Message());
    }
} //myButtonAdd_Click

private void button1_Click(Object sender, System.EventArgs e)
{
    if (myTextBox1.get_CausesValidation() == false && myTextBox2.
        get_CausesValidation() == false) {
        myTextBox1.set_CausesValidation(true);
        myTextBox2.set_CausesValidation(true);
        button1.set_Text("Disable Validation");
        myLabel.set_Text("Validation Enabled");
    }
    else {
        if (myTextBox1.get_CausesValidation() == true && myTextBox2.
            get_CausesValidation() == true) {
            myTextBox1.set_CausesValidation(false);
            myTextBox2.set_CausesValidation(false);
            button1.set_Text("Enable Validation");
            myLabel.set_Text("Validation Disabled");
        }
    }
} //button1_Click