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TextBoxBase.SelectionStart Property

Gets or sets the starting point of text selected in the text box.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

public int SelectionStart { get; set; }
/** @property */
public int get_SelectionStart ()

/** @property */
public void set_SelectionStart (int value)

public function get SelectionStart () : int

public function set SelectionStart (value : int)

Property Value

The starting position of text selected in the text box.

Exception typeCondition

ArgumentOutOfRangeException

The assigned value is less than zero.

If no text is selected in the control, this property indicates the insertion point for new text. 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. When text is selected in the text box control, changing this property might decrease the value of the SelectionLength property. 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. The value of the SelectionStart property never causes an increase in the SelectionLength property.

NoteNote

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). The text box must have focus in order for the caret to be moved.

The following code example uses TextBox, a derived class. It provides Click event handlers for MenuItem objects that perform Cut, Copy, Paste, and Undo operations. 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();
 }
 
 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 void Menu_Copy(Object sender, System.EventArgs e)
{
    // Ensure that text is selected in the text box.   
    if (textBox1.get_SelectionLength() > 0) {
        // Copy the selected text to the Clipboard.
        textBox1.Copy();
    }
} //Menu_Copy

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

private void Menu_Paste(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.get_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).Equals(get_DialogResult().No)) {
                // Move selection to the point after the current 
                // selection and paste.
                textBox1.set_SelectionStart(textBox1.get_SelectionStart() 
                    + textBox1.get_SelectionLength());
            }
        }
        // Paste current text in Clipboard into text box.
        textBox1.Paste();
    }
} //Menu_Paste

private void Menu_Undo(Object sender, System.EventArgs e)
{
    // Determine if last operation can be undone in text box.   
    if (textBox1.get_CanUndo() == true) {
        // Undo the last operation.
        textBox1.Undo();
        // Clear the undo buffer to prevent last action from being redone.
        textBox1.ClearUndo();
    }
} //Menu_Undo

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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