private void ConvertCurrency_Click(object sender, RoutedEventArgs e) { if (!String.IsNullOrEmpty(this.amountBox.Text)) { double result; ConvertService service = new ConvertService(); Devise devise = (Devise)this.deviseBox.SelectedItem; if (!service.TryConvert(this.amountBox.Text, devise.Taux, out result)) { this.errorText.Text = "La valeur que vous avez tapé est invalide !"; this.errorText.Visibility = Visibility.Visible; this.convertedBox.Text = ""; } else { this.InitializeError(); this.convertedBox.Text = result.ToString(); } } else { this.errorText.Text = "Veuillez entrer une valeur !"; this.errorText.Visibility = Visibility.Visible; } }