Description

Because a combo box does not (permanently) display its list like a list box, to show its content, the user can click the arrow button. Here is an example:

To support combo boxes, the .NET Framework provides a class named ComboBox. At design time, to add a combo box to your application, from the Common Controls section of the Toolbox, you can click the ComboBox button and click the form or a container. Like ListBox, the ComboBox class is derived from the ListControl class. Therefore, to programmatically create a combo box, declare a variable of type ComboBox, allocate its memory with the new operator and add it to the Controls collection of its container. Here is an example:

using System;
using System.Drawing;
using System.Windows.Forms;

public class Exercise : System.Windows.Forms.Form
{
    Label lblTitle;
    ComboBox cbxAcademicDisciplines;

    public Exercise()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        lblTitle = new Label();
        lblTitle.Text = "Academic Disciplines";
        lblTitle.Location = new Point(12, 12);
        lblTitle.AutoSize = true;
        Controls.Add(lblTitle);

        cbxAcademicDisciplines = new ComboBox();
        cbxAcademicDisciplines.Location = new Point(12, 32);

        Controls.Add(cbxAcademicDisciplines);
    }
}

public class Program
{
    static int Main()
    {
        System.Windows.Forms.Application.Run(new Exercise());
        return 0;
    }
}

This would produce:

1. Start Microsoft Visual C# and create a new Windows Application named CollegeParkAutoParts1
2. In the Solution Explorer, right-click Form1.cs and click Rename
3. Type Central.cs and press Enter
4. Design the form as follows:
    

   Control Text Name Other Properties GroupBox Parts Selection     Label Year   Font: Microsoft Sans Serif, 8.25pt, style=Bold Label Make   Microsoft Sans Serif, 8.25pt, style=Bold Label Model   Microsoft Sans Serif, 8.25pt, style=Bold Label Category   Microsoft Sans Serif, 8.25pt, style=Bold ComboBox   cbxCarYears   ComboBox   cbxMakes   ComboBox   cbxModels   ComboBox   cbxCategories   Label Available Parts   Font: Microsoft Sans Serif, 9.75pt, style=Bold ListBox   lbxPartNumbers   ListBox   lbxPartNames   ListBox   lbxUnitPrices   GroupBox Customer Selected Items     Label Part #     Label Part Name     Label Unit Price     Label Qty     Label Sub Total     TextBox   txtPartNumber1   TextBox   txtPartName1   TextBox 0.00 txtUnitPrice1 TextAlign: Right TextBox 0 txtQuantity1 TextAlign: Right TextBox 0.00 txtSubTotal1 TextAlign: Right Button Remove btnRemove1   TextBox   txtPartNumber2   TextBox   txtPartName2   TextBox 0.00 txtUnitPrice2 TextAlign: Right TextBox 0 txtQuantity2 TextAlign: Right TextBox 0.00 txtSubTotal2 TextAlign: Right Button Remove btnRemove2   TextBox   txtPartNumber3   TextBox   txtPartName3   TextBox 0.00 txtUnitPrice3 TextAlign: Right TextBox 0 txtQuantity3 TextAlign: Right TextBox 0.00 txtSubTotal3 TextAlign: Right Button Remove btnRemove3   TextBox   txtPartNumber4   TextBox   txtPartName4   TextBox 0.00 txtUnitPrice4 TextAlign: Right TextBox 0 txtQuantity4 TextAlign: Right TextBox 0.00 txtSubTotal4 TextAlign: Right Button Remove btnRemove4   TextBox   txtPartNumber5   TextBox   txtPartName5   TextBox 0.00 txtUnitPrice5 TextAlign: Right TextBox 0 txtQuantity5 TextAlign: Right TextBox 0.00 txtSubTotal5 TextAlign: Right Button Remove btnRemove5   TextBox   txtPartNumber6   TextBox   txtPartName6   TextBox 0.00 txtUnitPrice6 TextAlign: Right TextBox 0 txtQuantity6 TextAlign: Right TextBox 0.00 txtSubTotal6 TextAlign: Right Button Remove btnRemove6   Label Total Order     TextBox 0.00 txtTotalOrder   Button Close btnClose

5. Execute the application to test it
6. Close the form and return to your programming environment