public void calcul_textboxs()
{
double volume = camion.calculVolume(Convert.ToDouble(this.longint_tb.Text), Convert.ToDouble(this.largint_tb.Text), Convert.ToDouble(this.hautint_tb.Text));
double volumelibre = 300;
volume_tb.Text = Convert.ToString(volume);
volumelibre_tb.Text = Convert.ToString(volumelibre);
}