Create WPF TextBox that accepts only numbers

This question already has an answer here:

How do I get a TextBox to only accept numeric input in WPF? 27 answers

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Most implementations I have seen so far are using the PreviewTextInput event to implement the correct mask behavior. This one inherits from TextBox and this one uses attached properties. Both use .Net's MaskedTextProvider to provide the correct mask behaviour, but if you just want a simple 'numbers only' textbox you don't need this class.

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private void txt_TextChanged(object sender, TextChangedEventArgs e)
{
    TextBox textBox = sender as TextBox;
    int iValue = -1;

    if (Int32.TryParse(textBox.Text, out iValue) == false)
    {
         TextChange textChange = e.Changes.ElementAt<TextChange>(0);
         int iAddedLength = textChange.AddedLength;
         int iOffset = textChange.Offset;

         textBox.Text = textBox.Text.Remove(iOffset, iAddedLength);
    }
}

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In my humble opinion, the best way to fulfill this requirement is using only OnTextChanged event because it can handle the digit from keystroke and also be able to handle Copy+Paste from clipboard too. I hope that my VB code shown below can throw some light on this.

Private Sub NumericBox_TextChanged(sender As Object, e As TextChangedEventArgs) Handles Me.TextChanged
  Dim Buffer As New StringBuilder
  Dim Index As Integer = Me.SelectionStart
  For Each C In Me.Text
    If Char.IsDigit(C) Then
      Buffer.Append(C)
    ElseIf Me.SelectionStart > Buffer.Length Then
      Index -= 1
    End If
  Next
  Me.Text = Buffer.ToString
  Me.SelectionStart = Index
End Sub

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