TextBoxBase.SelectionStart Property
Definition
Important
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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; }[<System.ComponentModel.Browsable(false)>]
member this.SelectionStart : int with get, setPublic Property SelectionStart As IntegerProperty Value
The starting position of text selected in the text box.
- Attributes
Exceptions
The assigned value is less than zero.
Examples
Example 1
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();
}
}
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 ))
{
// 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)
{
// 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))
{
// 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)
{
// 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
Example 2
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
If no text is selected in the control, this property indicates the insertion point, or caret, 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.
You can programmatically move the selection within the text box by setting the SelectionStart and the SelectionLength properties.
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 TextBox must have focus in order for the selection or the caret to be moved. You can set the SelectionStart property of a TextBox that is ReadOnly by giving it the Focus first.
