TextBoxBase.SelectionStart TextBoxBase.SelectionStart TextBoxBase.SelectionStart TextBoxBase.SelectionStart Property

Definition

Ruft den Anfangspunkt des im Textfeld markierten Texts ab oder legt diesen fest. Gets or sets the starting point of text selected in the text box.

public:
 property int SelectionStart { int get(); void set(int value); };
[System.ComponentModel.Browsable(false)]
public int SelectionStart { get; set; }
member this.SelectionStart : int with get, set
Public Property SelectionStart As Integer

Property Value

Die Anfangsposition des im Textfeld markierten Texts. The starting position of text selected in the text box.

Exceptions

Der zugewiesene Wert ist kleiner als 0 (null). The assigned value is less than zero.

Examples

Beispiel 1Example 1

Das folgende Codebeispiel verwendet TextBox, eine abgeleitete Klasse.The following code example uses TextBox, a derived class. Es bietet Click -Ereignishandlern für MenuItem Objekte, die ausführen Ausschneiden, kopieren, einfügen und Rückgängig-Vorgänge.It provides Click event handlers for MenuItem objects that perform Cut, Copy, Paste, and Undo operations. In diesem Beispiel erfordert, dass eine TextBox Steuerelement mit dem Namen textBox1 erstellt wurde.This example requires that a TextBox control named textBox1 has been created.

private:
   void Menu_Copy( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Ensure that text is selected in the text box.   
      if ( textBox1->SelectionLength > 0 )
      {
         // Copy the selected text to the Clipboard.
         textBox1->Copy();
      }
   }

   void Menu_Cut( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Ensure that text is currently selected in the text box.   
      if (  !textBox1->SelectedText->Equals( "" ) )
      {
         // Cut the selected text in the control and paste it into the Clipboard.
         textBox1->Cut();
      }
   }

   void Menu_Paste( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Determine if there is any text in the Clipboard to paste into the text box.
      if ( Clipboard::GetDataObject()->GetDataPresent( DataFormats::Text ) == true )
      {
         // Determine if any text is selected in the text box.
         if ( textBox1->SelectionLength > 0 )
         {
            // Ask user if they want to paste over currently selected text.
            if ( MessageBox::Show( "Do you want to paste over current selection?",
               "Cut Example", MessageBoxButtons::YesNo ) == ::DialogResult::No )
            {
               // Move selection to the point after the current selection and paste.
               textBox1->SelectionStart = textBox1->SelectionStart + textBox1->SelectionLength;
            }
         }
         // Paste current text in Clipboard into text box.
         textBox1->Paste();
      }
   }

   void Menu_Undo( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Determine if last operation can be undone in text box.   
      if ( textBox1->CanUndo == true )
      {
         // Undo the last operation.
         textBox1->Undo();
         // Clear the undo buffer to prevent last action from being redone.
         textBox1->ClearUndo();
      }
   }
private void Menu_Copy(System.Object sender, System.EventArgs e)
 {
    // Ensure that text is selected in the text box.   
    if(textBox1.SelectionLength > 0)
        // Copy the selected text to the Clipboard.
        textBox1.Copy();
 }
 
 private void Menu_Cut(System.Object sender, System.EventArgs e)
 {   
     // Ensure that text is currently selected in the text box.   
     if(textBox1.SelectedText != "")
        // Cut the selected text in the control and paste it into the Clipboard.
        textBox1.Cut();
 }
 
 private void Menu_Paste(System.Object sender, System.EventArgs e)
 {
    // Determine if there is any text in the Clipboard to paste into the text box.
    if(Clipboard.GetDataObject().GetDataPresent(DataFormats.Text) == true)
    {
        // Determine if any text is selected in the text box.
        if(textBox1.SelectionLength > 0)
        {
          // Ask user if they want to paste over currently selected text.
          if(MessageBox.Show("Do you want to paste over current selection?", "Cut Example", MessageBoxButtons.YesNo) == DialogResult.No)
             // Move selection to the point after the current selection and paste.
             textBox1.SelectionStart = textBox1.SelectionStart + textBox1.SelectionLength;
        }
        // Paste current text in Clipboard into text box.
        textBox1.Paste();
    }
 }
 
 
 private void Menu_Undo(System.Object sender, System.EventArgs e)
 {
    // Determine if last operation can be undone in text box.   
    if(textBox1.CanUndo == true)
    {
       // Undo the last operation.
       textBox1.Undo();
       // Clear the undo buffer to prevent last action from being redone.
       textBox1.ClearUndo();
    }
 }
 
Private Sub Menu_Copy(sender As System.Object, e As System.EventArgs)
    ' Ensure that text is selected in the text box.   
    If textBox1.SelectionLength > 0 Then
        ' Copy the selected text to the Clipboard.
        textBox1.Copy()
    End If
End Sub
 
Private Sub Menu_Cut(sender As System.Object, e As System.EventArgs)
    ' Ensure that text is currently selected in the text box.   
    If textBox1.SelectedText <> "" Then
        ' Cut the selected text in the control and paste it into the Clipboard.
        textBox1.Cut()
    End If
End Sub
 
Private Sub Menu_Paste(sender As System.Object, e As System.EventArgs)
    ' Determine if there is any text in the Clipboard to paste into the text box.
    If Clipboard.GetDataObject().GetDataPresent(DataFormats.Text) = True Then
        ' Determine if any text is selected in the text box.
        If textBox1.SelectionLength > 0 Then
            ' Ask user if they want to paste over currently selected text.
            If MessageBox.Show("Do you want to paste over current selection?", _
                "Cut Example", MessageBoxButtons.YesNo) = DialogResult.No Then
                ' Move selection to the point after the current selection and paste.
                textBox1.SelectionStart = textBox1.SelectionStart + _
                    textBox1.SelectionLength
            End If
        End If 
        ' Paste current text in Clipboard into text box.
        textBox1.Paste()
    End If
End Sub

Private Sub Menu_Undo(sender As System.Object, e As System.EventArgs)
    ' Determine if last operation can be undone in text box.   
    If textBox1.CanUndo = True Then
        ' Undo the last operation.
        textBox1.Undo()
        ' Clear the undo buffer to prevent last action from being redone.
        textBox1.ClearUndo()
    End If
End Sub

Beispiel 2Example 2

Im folgenden Beispiel wird die SelectionStart Eigenschaft eine TextBox , ReadOnly ermöglicht es der Focus erste.The following example sets the SelectionStart property of a TextBox that is ReadOnly by giving it the Focus first.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        this.button1.Click += new System.EventHandler(this.ButtonClickWork);
    }

    private void ButtonClickWork(object sender, EventArgs e)
    {
        this.textBox1.Text = "Hello world!";
        this.textBox1.ReadOnly = true;

        this.textBox1.Focus();
        this.textBox1.SelectionStart = this.textBox1.SelectionStart + 1;
        this.textBox1.SelectionLength = 1;
    }
}
Public Class Form1

    Private Sub ButtonClickWork(ByVal sender As System.Object, ByVal e As System.EventArgs) _
        Handles Button1.Click

        Me.TextBox1.Text = "Hello world!"
        Me.TextBox1.ReadOnly = True

        Me.TextBox1.Focus()
        Me.TextBox1.SelectionStart = Me.TextBox1.SelectionStart + 1
        Me.TextBox1.SelectionLength = 1
    End Sub
End Class

Remarks

Wenn kein Text im Steuerelement ausgewählt ist, gibt diese Eigenschaft an der Einfügemarke oder ein Caretzeichen für den neuen Text.If no text is selected in the control, this property indicates the insertion point, or caret, for new text. Wenn Sie diese Eigenschaft auf eine Position hinter der Länge des Texts im Steuerelement festlegen, wird die Startposition der Bereichsauswahl hinter dem letzten Zeichen platziert werden.If you set this property to a location beyond the length of the text in the control, the selection start position will be placed after the last character. Wenn Text in das Textfeld-Steuerelement ausgewählt ist, das Ändern dieser Eigenschaft möglicherweise verringern Sie den Wert von der SelectionLength Eigenschaft.When text is selected in the text box control, changing this property might decrease the value of the SelectionLength property. Wenn es sich bei der restlichen Text im Steuerelement nach der Position angegeben die SelectionStart -Eigenschaft ist kleiner als der Wert des der SelectionLength -Eigenschaft wird der Wert des der SelectionLength Eigenschaft wird automatisch verringert.If the remaining text in the control after the position indicated by the SelectionStart property is less than the value of the SelectionLength property, the value of the SelectionLength property is automatically decreased. Der Wert des der SelectionStart Eigenschaft löst nie eine Zunahme der SelectionLength Eigenschaft.The value of the SelectionStart property never causes an increase in the SelectionLength property.

Sie können die Auswahl im Textfeld programmgesteuert verschieben, durch Festlegen der SelectionStart und SelectionLength Eigenschaften.You can programmatically move the selection within the text box by setting the SelectionStart and the SelectionLength properties.

Sie können die Einfügemarke innerhalb des Textfelds programmgesteuert verschieben, durch Festlegen der SelectionStart an die Position innerhalb des Textfelds, möchten Sie die Einfügemarke zu verschieben, und legen Sie, die SelectionLength Eigenschaft mit einem Wert von 0 (null).You can programmatically move the caret within the text box by setting the SelectionStart to the position within the text box where you want the caret to move to and set the SelectionLength property to a value of zero (0).

Die TextBox muss markiert sein, damit für die Auswahl oder Einfügemarke verschoben werden.The TextBox must have focus in order for the selection or the caret to be moved. Sie können festlegen, die SelectionStart Eigenschaft eine TextBox , ReadOnly indem Sie Ihren der Focus erste.You can set the SelectionStart property of a TextBox that is ReadOnly by giving it the Focus first.

Applies to