(e.KeyChar (char)Keys.Enter && Txt1.Text "") { e.Handled = true; MessageBox.Show("Veuillez saisir ...); }
private Txt1_KeyPress(object sender, KeyEventArgs e) { if(e.KeyCode Keys.Enter && Txt1.Text "") { Txt1.SetFocus(); MessageBox.Show("Veuillez saisir....."); } }