The Main Menu

Introduction

A menu is a list of actions that can be performed on a program. To be aware of these actions, the list must be presented to the user upon request. On a typical DOS (Microsoft Windows) or Terminal (UNIX/Linux) application, a menu is presented with numerical or character options that the user can type and press Enter. An example would be:

Here are the various options:
1. Register a new student
2. Review a student's information
3. Enter student's grades
4. Close the application

The user would then enter the number (or character) that corresponds to the desired option and continue using the program. For a graphical application, a menu is presented as a list of words and, using a mouse or a keyboard, the user can select the desired item from the menu.

To enhance the functionality of a graphical application, also to take advantage of the mouse and the keyboard, there are various types of menus. A menu is considered a main menu when it carries most of the actions the user can perform on a particular application. Such a menu is positioned in the top section of the form in which it is used.

A main menu is divided in categories of items and each category is represented by a word. Here is an example of categories of menus as File, Edit, View, Insert, Format, and Help:

To use a menu, the user first clicks one of the words that displays on top. When clicked, the menu expands and displays a list of items that belong to that category. Here is an example:

There is no strict rule on how a menu is organized. There are only suggestions. For example, actions that are related to file processing, such as creating a new file, opening an existing file, saving a file, printing the open file, or closing the file usually stay under a category called File. In the same way, actions related to viewing documents can be listed under a View menu category.

Practical Learning: Creating a Menu

1. Start Microsoft Visual Studio
2. Create a new Windows Forms App named AutoPartsInventory3
3. In the Solution Explorer, right-click AutoPartsInventory3 -> New -> Folder
4. Type Models as the name of the folder
5. In the Solution Explorer, right-click Models -> Add -> Class...
6. Type AutoPart as the name of the class
7. Press Enter
8. Change the document as follows:

   namespace AutoPartsInventory3.Models
   {
       internal record class AutoPart
       {
           public int     PartNumber { get; set; }
           public int     CarYear    { get; set; }
           public string? Make       { get; set; }
           public string? Model      { get; set; }
           public string? Category   { get; set; }
           public string? PartName   { get; set; }
           public double  UnitPrice  { get; set; }
       }
   }

9. In the Solution Explorer, right-click Models -> Add -> Class...
10. Type Repository as the name of the class
11. Press Enter
12. Change the document as follows:

    namespace AutoPartsInventory3.Models
    {
        internal static class Repository
        {
            public static AutoPart[] AutoParts = new AutoPart[100];
    
            static Repository()
            {
                for (int i = 0; i < AutoParts.Length; i++)
                {
                    AutoParts[i] = new AutoPart()
                    {
                        PartNumber = 0,
                        CarYear    = i,
                        Make       = string.Empty,
                        Model      = string.Empty,
                        Category   = string.Empty,
                        PartName   = string.Empty,
                        UnitPrice  = 0d
                    };
                }
            }
    
            private static int GetFirst0Index()
            {
                for (int i = 0; i < AutoParts.Length; i++)
                {
                    if (AutoParts[i].PartNumber == 0)
                    {
                        return i;
                    }
                }
    
                return 0;
            }
    
            public static void Add(in AutoPart part)
            {
                int index = GetFirst0Index();
                
                AutoParts[index].PartNumber = part.PartNumber;
                AutoParts[index].CarYear = part.CarYear;
                AutoParts[index].Make = part.Make;
                AutoParts[index].Model = part.Model;
                AutoParts[index].Category = part.Category;
                AutoParts[index].PartName = part.PartName;
                AutoParts[index].UnitPrice = part.UnitPrice;
            }
        }
    }

13. To create a new form, on the main menu, click Project -> Add Form (Windows Forms)...
14. In the middle list of the Add New Item dialog box, make sure Form (Windows Forms) and selected and change the file Name to AutoPartNew
15. Click Add
16. Design the form as follows:

    

    Control		(Name)	Text	Modifiers	Other Properties
    Label			&Part #:
    TextBox		txtPartNumber		Public
    PictureBox		pbxAutoPart			BorderStyle: FixedSingle SizeMode: AutoSize
    Label			&Year:
    ComboBox		cbxYears		Public
    Label			&Make:	Public
    ComboBox		cbxMakes		Public
    Label			M&odel:
    TextBox		txtModel		Public
    Label			Ca&tegory:
    ComboBox		cbxCategories		Public
    Label			Part Na&me
    TextBox		txtPartName		Public	Mutiline: True ScrollBars: Vertical
    Label			&Unit Price:
    TextBox		txtUnitPrice		Public	TextAlign: Right
    Label			__________________________
    Button		btnSaveAutoPart	Sa&ve Auto-Part
    Button		btnClose	Close

17. Double-click an unoccupied area of the form to generate its Load event
18. Return to the form and click its Part # text box
19. In the Properties window, click the Events button
20. In the Events section of the Properties window, double-click Leave
21. Return to the form and double-click the Save Auto Part button
22. Return to the form and double-click the Close
23. Change the document as follows:

    using AutoPartsInventory3.Models;
    
    namespace AutoPartsInventory3
    {
        public partial class AutoPartNew : Form
        {
            public AutoPartNew()
            {
                InitializeComponent();
            }
    
            public void InitializeStoreItem()
            {
                txtPartNumber.Text = string.Empty;
                cbxYears.Items.Clear();
                cbxMakes.Items.Clear();
                cbxCategories.Items.Clear();
    
                for (int year = DateTime.Today.Year + 1; year >= 2000; year--)
                    cbxYears.Items.Add(year);
    
                cbxMakes.Items.Add("Kia");
                cbxMakes.Items.Add("GMC");
                cbxMakes.Items.Add("Ford");
                cbxMakes.Items.Add("Jeep");
                cbxMakes.Items.Add("Buick");
                cbxMakes.Items.Add("Dodge");
                cbxMakes.Items.Add("Honda");
                cbxMakes.Items.Add("Toyota");
                cbxMakes.Items.Add("Cadillac");
                cbxMakes.Items.Add("Chrysler");
                cbxMakes.Items.Add("Chevrolet");
                cbxMakes.Items.Add("Volkswagen");
    
                cbxCategories.Items.Add("Starters");
                cbxCategories.Items.Add("Brake Kits");
                cbxCategories.Items.Add("Air Filters");
                cbxCategories.Items.Add("Oil Filters");
                cbxCategories.Items.Add("Alternators");
                cbxCategories.Items.Add("Drum Brakes");
                cbxCategories.Items.Add("Bearings & Seals");
                cbxCategories.Items.Add("Alternators & Generators");
                cbxCategories.Items.Add("Shocks, Struts & Suspension");
    
                pbxAutoPart.Image = Image.FromFile(@"E:\College Park Auto-Parts\Generic.png");
            }
    
            private void AutoPartNew_Load(object sender, EventArgs e)
            {
                InitializeStoreItem();
            }
    
            private void txtPartNumber_Leave(object sender, EventArgs e)
            {
                if (!string.IsNullOrEmpty(txtPartNumber.Text))
                {
                    pbxAutoPart.Image = Image.FromFile(@"E:\College Park Auto-Parts\" + txtPartNumber.Text + ".png");
    
                    Width  = pbxAutoPart.Left + pbxAutoPart.Image.Width + 40;
                    Height = pbxAutoPart.Top + pbxAutoPart.Image.Height + 80;
                }
            }
    
            private void btnSaveAutoPart_Click(object sender, EventArgs e)
            {
                AutoPart item = new AutoPart()
                {
                    PartNumber = int.Parse(txtPartNumber.Text),
                    CarYear    = int.Parse(cbxYears.Text),
                    Make       = cbxMakes.Text,
                    Model      = txtModel.Text,
                    Category   = cbxCategories.Text,
                    PartName   = txtPartName.Text,
                    UnitPrice  = double.Parse(txtUnitPrice.Text),
                };
    
                Repository.Add(item);
                InitializeStoreItem();
    
                cbxYears.Text      = string.Empty;
                cbxMakes.Text      = string.Empty;
                txtModel.Text      = string.Empty;
                cbxCategories.Text = string.Empty;
                txtPartNumber.Text = string.Empty;
                txtPartName.Text   = string.Empty;
                txtUnitPrice.Text  = string.Empty;
            }
    
            private void btnClose_Click(object sender, EventArgs e)
            {
                Close();
            }
        }
    }

24. To create a new form, in the Solution Explorer, right-click AutoPartsInventory3 -> Add -> Form (Windows Forms)...
25. Change the file Name to AutoPartEditor
26. Press Enter
27. Enlarge the form to give it the same size as the New Auto Part form
28. Copy all the controls in the New Auto Part form and paste them in the new Auto Part Editor form
29. Add a button to the Auto Part Editor form and change the Save Auto Part button as follows:

    

    Control		(Name)	Text
    Button		btnFindAutoPart	&Find Auto Part
    Button		btnUpdateAutoPart	&Update Auto-Part

30. On the form, double-click the Find Auto Part button
31. Return to the form and double-click the Update Auto Part button
32. Return to the form and double-click the Close
33. Change the document as follows:

    using AutoPartsInventory3.Models;
    
    namespace AutoPartsInventory3
    {
        public partial class AutoPartEditor : Form
        {
            public AutoPartEditor()
            {
                InitializeComponent();
            }
    
            public void InitializeStoreItem()
            {
                txtPartNumber.Text = string.Empty;
                cbxYears.Items.Clear();
                cbxMakes.Items.Clear();
                txtModel.Text = string.Empty;
                cbxCategories.Items.Clear();
                txtPartName.Text = string.Empty;
                txtUnitPrice.Text = string.Empty;
    
                for (int year = DateTime.Today.Year + 1; year >= 2000; year--)
                    cbxYears.Items.Add(year);
    
                cbxMakes.Items.Add("Kia");
                cbxMakes.Items.Add("GMC");
                cbxMakes.Items.Add("Ford");
                cbxMakes.Items.Add("Jeep");
                cbxMakes.Items.Add("Buick");
                cbxMakes.Items.Add("Dodge");
                cbxMakes.Items.Add("Honda");
                cbxMakes.Items.Add("Toyota");
                cbxMakes.Items.Add("Cadillac");
                cbxMakes.Items.Add("Chrysler");
                cbxMakes.Items.Add("Chevrolet");
                cbxMakes.Items.Add("Volkswagen");
    
                cbxCategories.Items.Add("Starters");
                cbxCategories.Items.Add("Brake Kits");
                cbxCategories.Items.Add("Air Filters");
                cbxCategories.Items.Add("Oil Filters");
                cbxCategories.Items.Add("Alternators");
                cbxCategories.Items.Add("Drum Brakes");
                cbxCategories.Items.Add("Bearings & Seals");
                cbxCategories.Items.Add("Alternators & Generators");
                cbxCategories.Items.Add("Shocks, Struts & Suspension");
    
                cbxYears.Text = string.Empty;
                cbxMakes.Text = string.Empty;
                cbxCategories.Text = string.Empty;
            }
    
            public void ResizeFormBasedOnPictureBox()
            {
                pbxAutoPart.Image = Image.FromFile(@"E:\College Park Auto-Parts\" + txtPartNumber.Text + ".png");
    
                Width  = pbxAutoPart.Left + pbxAutoPart.Image.Width + 40;
                Height = pbxAutoPart.Top + pbxAutoPart.Image.Height + 80;
            }
    
            private void btnFindAutoPart_Click(object sender, EventArgs e)
            {
                foreach (AutoPart part in Repository.AutoParts)
                {
                    if (part.PartNumber == int.Parse(txtPartNumber.Text))
                    {
                        cbxYears.Text      = part.CarYear.ToString();
                        cbxMakes.Text      = part.Make;
                        txtModel.Text      = part.Model;
                        cbxCategories.Text = part.Category;
                        txtPartName.Text   = part.PartName;
                        txtUnitPrice.Text  = part.UnitPrice.ToString();
    
                        pbxAutoPart.Image  = Image.FromFile(@"E:\College Park Auto-Parts\" + txtPartNumber.Text + ".png");
    
                        Width  = pbxAutoPart.Left + pbxAutoPart.Image.Width  + 40;
                        Height = pbxAutoPart.Top  + pbxAutoPart.Image.Height + 80;
                        break;
                    }
                }
            }
    
            private void btnUpdateAutoPart_Click(object sender, EventArgs e)
            {
                foreach (AutoPart part in Repository.AutoParts)
                {
                    if (part.PartNumber == int.Parse(txtPartNumber.Text))
                    {
                        part.CarYear   = int.Parse(cbxYears.Text);
                        part.Make      = cbxMakes.Text;
                        part.Model     = txtModel.Text;
                        part.Category  = cbxCategories.Text;
                        part.PartName  = txtPartName.Text;
                        part.UnitPrice = double.Parse(txtUnitPrice.Text);
                        break;
                    }
                }
    
                InitializeStoreItem();
            }
    
            private void btnClose_Click(object sender, EventArgs e)
            {
                Close();
            }
        }
    }

34. To create a new form, in the Solution Explorer, right-click AutoPartsInventory3 -> Add -> Form (Windows Forms)...
35. Change the file Name to AutoPartDelete
36. Press Enter
37. Enlarge the form to give it the same size as the Auto Part Editor form
38. Copy all the controls in the Auto Part Editor form and paste them in the Auto Part Delete form
39. Change the design of the form as follows:

    

    Control		(Name)	Text	Modifiers
    TextBox		txtYear		Public
    TextBox		txtMake		Public
    TextBox		txtCategory		Public
    Button		btnDeleteAutoPart	&Delete Auto-Part

40. On the form, double-click the Find Auto Part button
41. Return to the form and double-click the Delete Auto Part button
42. Return to the form and double-click the Close button
43. Change the document as follows:

    using AutoPartsInventory3.Models;
    
    namespace AutoPartsInventory3
    {
        public partial class AutoPartDelete : Form
        {
            public AutoPartDelete()
            {
                InitializeComponent();
            }
    
            public void InitializeStoreItem()
            {
                txtPartNumber.Text = string.Empty;
                txtYear.Text       = string.Empty;
                txtMake.Text       = string.Empty;
                txtModel.Text      = string.Empty;
                txtCategory.Text   = string.Empty;
                txtPartName.Text   = string.Empty;
                txtUnitPrice.Text  = string.Empty;
            }
    
            public void ResizeFormBasedOnPictureBox()
            {
    
                pbxAutoPart.Image = Image.FromFile(@"E:\College Park Auto-Parts\" + txtPartNumber.Text + ".png");
    
                Width  = pbxAutoPart.Left + pbxAutoPart.Image.Width  + 40;
                Height = pbxAutoPart.Top  + pbxAutoPart.Image.Height + 80;
    
            }
    
            private void btnFindAutoPart_Click(object sender, EventArgs e)
            {
                foreach (AutoPart part in Repository.AutoParts)
                {
                    if (part.PartNumber == int.Parse(txtPartNumber.Text))
                    {
                        txtYear.Text = part.CarYear.ToString();
                        txtMake.Text = part.Make;
                        txtModel.Text = part.Model;
                        txtCategory.Text = part.Category;
                        txtPartName.Text = part.PartName;
                        txtUnitPrice.Text = part.UnitPrice.ToString();
    
                        pbxAutoPart.Image = Image.FromFile(@"E:\College Park Auto-Parts\" + txtPartNumber.Text + ".png");
    
                        Width = pbxAutoPart.Left + pbxAutoPart.Image.Width + 40;
                        Height = pbxAutoPart.Top + pbxAutoPart.Image.Height + 80;
                        break;
                    }
                }
            }
    
            private void btnDeleteAutoPart_Click(object sender, EventArgs e)
            {
                foreach (AutoPart part in Repository.AutoParts)
                {
                    if (part.PartNumber == int.Parse(txtPartNumber.Text))
                    {
                        part.PartNumber = 0;
                        part.CarYear    = 0;
                        part.Make       = string.Empty;
                        part.Model      = string.Empty;
                        part.Category   = string.Empty;
                        part.PartName   = string.Empty;
                        part.UnitPrice  = 0d;
                        break;
                    }
                }
    
                InitializeStoreItem();
            }
    
            private void btnClose_Click(object sender, EventArgs e)
            {
                Close();
            }
        }
    }

44. To create a new form, on the main menu, click Project -> Add Form (Windows Forms)...
45. In the middle list of the Add New Item dialog box, click About Box (Windows Forms)
46. Change the file Name to AboutCPAP
47. Click Add
48. In the Solution Explorer, right-click Form1.cs and click Rename
49. Type AutoPartsInventory (to get AutoPartsInventory.cs)
50. Press Enter three times

Main Menu Creation

To support actions that are used to graphically enhance the functionality of an application, the .NET Framework provides a class named ToolStrip. To support menus for an application, the .NET Framework provides a class named MenuStrip (in Microsoft Visual Studio 2002 and 2003, the main menu was implemented through the MainMenu class, which is still available but lacks some features).

To graphically create a main menu, in the Menus & Toolbars section of the Toolbox, you can click the MenuStrip button and click the form that will use the menu. After clicking the form, an empty menu is initiated:

Like every control, the main menu must have a name. After adding the menu strip to a form, you can accept the suggested name or, in the Properties window, click (Name) and type the desired name. You can then use the menu placeholder to add the necessary menu item(s).

To programmatically create a main menu, declare a variable of type MenuStrip and initialize it with its default constructor. Because the main menu is primarily a control, you must add it to the list of controls of the form. Here is an example:

using System.Windows.Forms;

public class Exercise : Form
{
    MenuStrip mnuMain;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();
        Controls.Add(mnuMain);
    }

    static int Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        System.Windows.Forms.Application.Run(new Exercise());
        return 0;
    }
}

Menu Categories

In our introduction, we saw that a main menu was made of categories represented in the top section. After adding a MenuStrip, you can start creating the desired menu categories. To graphically create a menu category:

• In the menu strip, click the Type Here line and type the desired string
• In the menu strip, click Type Here. Then, in the Properties window, click the Text field and type the desired string

To create the next menu category, click Type Here on the right side of the previous menu category. In the same way, you can continue creating the desired menu categories. Here is an example:

Besides clicking Type Here and typing a string, an alternative is to get assisted by a dialog box. To open it:

• Under the form, right-click the menu strip and click Edit Items...
• Under the form, click the menu strip object and, in the Properties window, you can click the ellipsis button of the Items field
• While the menu strip is selected under the form, in the status bar of the Properties window, click Edit Items...

A dialog box, titled Items Collection Editor, would come up:

To create a menu category, in the Select Item And Add To List Below combo box, select MenuItem and click the Add button. In the right list, configure the menu item. At a minimum, you should specify its caption in the Text field. Like every control, each menu item has a name. To make sure you can easily recognize it in your code, when creating a menu item, you should give it a name unless you are satisfied with the suggested one. After creating the menu categories, you can click OK and keep the dialog box opened for more options.

To support menu items, the .NET Framework provides a class named ToolStripMenuItem. Using it, to create a menu category, declare a handle to this class and initialize it using one of its constructors. The default constructor is used to create a menu item without specifying any of its options. Here is an example:

ppublic class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    ToolStripMenuItem mnuFile;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();
        mnuFile = new ToolStripMenuItem();

        Controls.Add(mnuMain);
    }
}

To specify the caption that will be displayed on a menu category, you can use the following constructor of the ToolStripMenuItem class:

public ToolStripMenuItem(string text);

Here is an example:

public class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    ToolStripMenuItem mnuFile;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();
        mnuFile = new ToolStripMenuItem("File");

        Controls.Add(mnuMain);
    }
}

If you had instantiated the class using its default constructor, to specify its caption, the ToolStripMenuItem class is equipped with a property named Text. Therefore, assign a string to this property. Here is an example:

public class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    ToolStripMenuItem mnuFile;
    ToolStripMenuItem mnuEdit;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();
        mnuFile = new ToolStripMenuItem("File");
        mnuEdit = new ToolStripMenuItem();
        mnuEdit.Text = "Edit";

        Controls.Add(mnuMain);
    }
}

In the same way, you can create as many menu categories as you judge necessary for your application.

Introduction to Menu Items

In our introduction, we saw that if you click a menu category, a list comes up. Here is an example:

The objects under a menu category are referred to as menu items. To graphically create a menu item, first access the menu strip, which you can do by clicking it under the form. On the form, click a menu category. Once you do this, a placeholder would be displayed under it:

To create a menu item:

• Under a category, click Type Here and type the desired caption
• Click the menu category. Then, in the Properties window, click Text and type the desired string

In the same way, to create the next menu item, under the same category, click the next Type Here and type the desired caption or change the Text value in the Properties window.

An alternative is to use a dialog box. To access it, in the menu designer:

• Right-click the menu category and click Edit Drop Down Items...
• Click the menu category. Then, in the Properties window, click the ellipsis button of the DropDownItems field

The Items Collection Editor dialog box would come up:

To create a menu item, in the Select Item And Add To List Below combo box, select MenuItem and click Add. On the right side, configure the menu item as you see fit. At a minimum, you should specify its caption in the Text field.

Both the menu category and the menu item are created using the ToolStripMenuItem class. Here are examples:

public class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    
    ToolStripMenuItem mnuFile;
    ToolStripMenuItem mnuNew;
    ToolStripMenuItem mnuExit;
    ToolStripMenuItem mnuEdit;
    ToolStripMenuItem mnuCopy;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();
        
        mnuFile = new ToolStripMenuItem("File");
        mnuNew  = new ToolStripMenuItem("New");
        mnuExit = new ToolStripMenuItem("Exit");
        mnuEdit = new ToolStripMenuItem("Edit");
        mnuCopy = new ToolStripMenuItem("Copy");

        Controls.Add(mnuMain);
    }
}

Associating Menu Items to Menu Categories

If you visually create your main menu, the form designer takes care of most details behind the scenes. For example, each menu item is automatically added to its parent menu category. If you programmatically create your main menu, you must associate each menu item to its parent menu category.

To support menu categories, ToolStripMenuItem, the class used to create menu categories, is derived from a class named ToolStripDropDownItem. The ToolStripDropDownItem class is abstract, which means you cannot instantiate it. Instead, it provides functionality to other classes derived from it. The ToolStripDropDownItem class is based on the ToolStripItem class.

To support menu items, the ToolStripDropDownItem class is equipped with a property named DropDownItems. This property is of type ToolStripItemCollection.

To specify that a menu item will be part of a menu category, call the Add() method of the ToolStripItemCollection class. This method is overloaded with various versions. One of the versions uses the following syntax:

public int Add(ToolStripItem value);

This version allows you to pass a ToolStripItem-type of item class, such as a ToolStripMenuItem object. Here is an example:

public class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    
    ToolStripMenuItem mnuEdit;
    ToolStripMenuItem mnuCopy;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();
        
        mnuEdit = new ToolStripMenuItem("Edit");
        mnuCopy = new ToolStripMenuItem("Copy");
        mnuEdit.DropDownItems.Add(mnuCopy);

        Controls.Add(mnuMain);
    }
}

The ToolStripItemCollection class also allows you to create a menu item without going through a ToolStripItem-type of object. To support this, it provides the following version of its Add() method:

public ToolStripItem Add(string text);

This method takes as argument the text that the menu item would display and it returns the ToolStripItem item that was created. Here is an example:

public class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    
    ToolStripMenuItem mnuEdit;
    ToolStripMenuItem mnuCopy;
    ToolStripMenuItem mnuPaste;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();
        
        mnuEdit = new ToolStripMenuItem("Edit");
        mnuCopy	= new ToolStripMenuItem("Copy");
        mnuEdit.DropDownItems.Add(mnuCopy);
        mnuPaste = (ToolStripMenuItem)mnuEdit.DropDownItems.Add("Paste");

        Controls.Add(mnuMain);
    }
}

Instead of adding one menu item at a time, you can create an array of menu items and then add it to a category in one row. To support this, the ToolStripItemCollection class is equipped with a method named AddRange method. This method is overloaded with two versions. One of the versions uses the following syntax:

public void AddRange(ToolStripItem[] toolStripItems);

When calling this method, you must pass it an array of ToolStripItem-type of objects. Here are two examples:

public class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    
    ToolStripMenuItem mnuFile;
    ToolStripMenuItem mnuNew;
    ToolStripMenuItem mnuOpen;
    ToolStripMenuItem mnuExit;
    ToolStripMenuItem mnuEdit;
    ToolStripMenuItem mnuCopy;
    ToolStripMenuItem mnuPaste;
    ToolStripMenuItem mnuHelp;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();

        mnuFile = new ToolStripMenuItem("File");
        mnuNew = new ToolStripMenuItem("New");
        mnuOpen = new ToolStripMenuItem("Open");
        mnuExit = new ToolStripMenuItem("Exit");
        ToolStripMenuItem[] mnuFileItems = { mnuNew, mnuOpen, mnuExit };
        mnuFile.DropDownItems.AddRange(mnuFileItems);

        mnuEdit = new ToolStripMenuItem("Edit");
        mnuCopy = new ToolStripMenuItem("Copy");
        mnuEdit.DropDownItems.Add(mnuCopy);
        mnuPaste = (ToolStripMenuItem)mnuEdit.DropDownItems.Add("Paste");

        mnuHelp = new ToolStripMenuItem("Help");
        ToolStripMenuItem[] mnuHelpItems =
        { 
            new ToolStripMenuItem("Search"),
            new ToolStripMenuItem("Contents"),
            new ToolStripMenuItem("Index"),
            new ToolStripMenuItem("Support Web Site"),
            new ToolStripMenuItem("About this application")
        };
        mnuHelp.DropDownItems.AddRange(mnuHelpItems);

        Controls.Add(mnuMain);
    }
}

Associating Menu Categories to the Main Menu

If you visually create your main menu, each menu category is automatically assigned to the menu strip. If you programmatically create your main menu, you must take care of this in order to show the whole menu.

After creating the menu categories, you can add them to the main menu. To support this, the ToolStrip class is equipped with a property named Items and it makes this property available to the MenuStrip class. The Items property is of type ToolStripItemCollection. To add a menu category to a MenuStrip object, you can call the Add() method of the ToolStripItemCollection class. This method is overloaded with various versions and one of them uses the following version:

public int Add(ToolStripItem value);

You can call this version and pass it a ToolStripItem-type of object, such as a ToolStripMenuItem value. Here is an example:

public class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    
    ToolStripMenuItem mnuFile;
    ToolStripMenuItem mnuNew;
    ToolStripMenuItem mnuOpen;
    ToolStripMenuItem mnuExit;
    ToolStripMenuItem mnuEdit;
    ToolStripMenuItem mnuCopy;
    ToolStripMenuItem mnuPaste;
    ToolStripMenuItem mnuHelp;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();

        mnuFile = new ToolStripMenuItem("File");
        mnuNew = new ToolStripMenuItem("New");
        mnuOpen = new ToolStripMenuItem("Open");
        mnuExit = new ToolStripMenuItem("Exit");
        ToolStripMenuItem[] mnuFileItems = { mnuNew, mnuOpen, mnuExit };
        mnuFile.DropDownItems.AddRange(mnuFileItems);

        mnuEdit = new ToolStripMenuItem("Edit");
        mnuCopy = new ToolStripMenuItem("Copy");
        mnuEdit.DropDownItems.Add(mnuCopy);
        mnuPaste = (ToolStripMenuItem)mnuEdit.DropDownItems.Add("Paste");

        mnuHelp = new ToolStripMenuItem("Help");
        ToolStripMenuItem[] mnuHelpItems =
        { 
            new ToolStripMenuItem("Search"),
            new ToolStripMenuItem("Contents"),
            new ToolStripMenuItem("Index"),
            new ToolStripMenuItem("Support Web Site"),
            new ToolStripMenuItem("About this application")
        };
        mnuHelp.DropDownItems.AddRange(mnuHelpItems);

        mnuMain.Items.Add(mnuFile);
        Controls.Add(mnuMain);
    }
}

In the same way, you can add the other items. Alternatively, you can create an array of menu categories and add them in a row. To support this, the ToolStripItemCollection is equipped with the AddRange() method that is overloaded with two versions. One of the versions uses the following syntax:

public void AddRange(ToolStripItem[] toolStripItems);

When calling this method, pass it an array of ToolStripItem types of values. Here is an example:

public class Exercise : System.Windows.Forms.Form
{
    MenuStrip mnuMain;
    
    ToolStripMenuItem mnuFile;
    ToolStripMenuItem mnuNew;
    ToolStripMenuItem mnuOpen;
    ToolStripMenuItem mnuExit;
    ToolStripMenuItem mnuEdit;
    ToolStripMenuItem mnuCopy;
    ToolStripMenuItem mnuPaste;

    ToolStripMenuItem mnuView;

    ToolStripMenuItem mnuHelp;

    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        mnuMain = new MenuStrip();

        mnuFile = new ToolStripMenuItem("File");
        mnuNew = new ToolStripMenuItem("New");
        mnuOpen = new ToolStripMenuItem("Open");
        mnuExit = new ToolStripMenuItem("Exit");
        ToolStripMenuItem[] mnuFileItems = { mnuNew, mnuOpen, mnuExit };
        mnuFile.DropDownItems.AddRange(mnuFileItems);

        mnuEdit = new ToolStripMenuItem("Edit");
        mnuCopy = new ToolStripMenuItem("Copy");
        mnuEdit.DropDownItems.Add(mnuCopy);
        mnuPaste = (ToolStripMenuItem)mnuEdit.DropDownItems.Add("Paste");

        mnuView = new ToolStripMenuItem("View");
        ToolStripMenuItem[] mnuViewItems =
        {
	    new ToolStripMenuItem("Standard Toolbar"),
	    new ToolStripMenuItem("Formatting Toolbar"),
	    new ToolStripMenuItem("Status Bar")
        };
        mnuView.DropDownItems.AddRange(mnuViewItems);

        mnuHelp = new ToolStripMenuItem("Help");
        ToolStripMenuItem[] mnuHelpItems =
        { 
            new ToolStripMenuItem("Search"),
            new ToolStripMenuItem("Contents"),
            new ToolStripMenuItem("Index"),
            new ToolStripMenuItem("Support Web Site"),
            new ToolStripMenuItem("About this application")
        };
        mnuHelp.DropDownItems.AddRange(mnuHelpItems);

        ToolStripMenuItem[] mnuAccessories = { mnuView, mnuHelp };
        mnuMain.Items.Add(mnuFile);
        mnuMain.Items.AddRange(mnuAccessories);

        Controls.Add(mnuMain);
    }
}

This would produce:

Practical Learning: Creating Menu Items

1. In the Toolbox, expand Menus & Toolbars
2. In the Menus & Toolbars section of the Toolbox, click MenuStrip and click the form
3. In the Properties window, click (Name) and type msMainMenu
4. Still in the Properties window, click Items and click its button
5. Using the Add button, create three items as follows:

   Text	(Name)
   File	miFile
   Edit	miEdit
   Help	miHelp

6. In the Members list of the Items Collection Editor, click miFile
7. In the right list, click DropDownItems and click its button
8. Using the Add button, create two items as follows:

   Text	(Name)
   New Auto-Part	miFileNewAutoPart
   Exit	miFileExit

9. On the Items Collection Editor (miFile.DropDownItems) dialog box, click OK
10. In the Members list of the Items Collection Editor, click miEdit
11. In the right list, click DropDownItems and click its button
12. Using the Add button, create two items as follows:

    Text	(Name)
    Update Auto Part	miEditUpdateAutoPart
    Delete Auto Part	miEditDeleteAutoPart

13. On the Items Collection Editor (miEdit.DropDownItems) dialog box, click OK
14. In the Members list of the Items Collection Editor, click miHelp
15. In the right list, click DropDownItems and click its button
16. Using the Add button, create an item as follows:

    Text	(Name)
    About CPAP	miHelpAbout

17. On the Items Collection Editor (miHelp.DropDownItems) dialog box, click OK
18. On the Items Collection Editor dialog box, click OK
19. In the Toolbox, expand the Components section and click ImageList
20. Click the form
21. While the image list is selected below the form, in the Properties window, click (Name) and type ilAutoParts and press Enter
22. Still in the Properties window for the image list, click Images and click its Images button
23. Continuously click the Add button. Add , , , , , , , , , and
24. Complete the design of the form as follows:

    

    Control		(Name)	Text	Other Properties
    Label			College Park Auto-Parts	Font: Times New Roman, 36pt, style=Bold ForeColor: Blue
    Label				BackColor: Maroon AutoSize: False
    Label			Part Identification _______
    TreeView		tvwAutoParts		ImageList: imgAutoParts
    ListView		lvwAutoParts		FullRowSelect: True GridLines: True View: Details
    PictureBox		pbxAutoPart		BorderStyle: FixedSingle SizeMode: AutoSize

25. On the form, right-click the list view and click Edit Columns...
26. Create the columns as follows:

    (Name)	Text	TextAlign	Width
    colPartNumber	Part #		100
    colPartName	Part Name/Description		700
    colUnitPrice	Unit Price	Right	100

27. Click OK
28. Double-click an unoccupied area of the form to generate its Load event
29. Return to the form and click the tree view
30. In the Properties window, click the Events button
31. In the Events section of the Properties window, double-click NodeMouseClick
32. Return to the form and click the list view
33. In the Events section of the Properties window, double-click ItemSelectionChanged

Writing Code for a Menu Item

If you create one or more menu items as we have just done, to write code for one of the menu items, you can double-click the menu item. This would open the Click event of the menu item in the Code Editor and you can start writing the desired code for that item.

Contextual Menus

Introduction

In our introduction to the main menu, we saw that, to access it, the user can click one of its categories. A contextual menu is one that appears when the user right-clicks an area of an application or form. In most applications, when the user right-clicks a title bar, the operating system is configured to display a system menu. Here is an example:

A menu is considered, or qualifies as, popup if, or because, it can appear anywhere on the form as the programmer wishes. Such a menu is also referred to as context-sensitive or contextual because its appearance and behavior depend on where it displays on the form or on a particular control. The person who creates the application decides if or where the contextual menu would appear. Because this characteristic is up to the programmer, the same application can display different types of popup menus depending on where the user right-clicks. Here are examples:

The first difference between a main menu and a popup menu is that a popup menu appears as one category or one list of items and not like a group of categories of menus like a main menu. Secondly, while a main menu by default is positioned on the top section of a form, a popup menu doesn't have a specific location on the form.

Creating a Contextual Menu

To support the creation and management of contextual menus, the .NET Framework provides a class named ContextMenuStrip. This class is derived from ToolStripDropDownMenu, which itself is based on the ToolStripDropDown class. The ToolStripDropDown class is derived from ToolStrip.

To visually create a contextual menu, in the Menus & Toolbars section of the Toolbox, click the ContextMenuStrip button and click the form. Once you have a ContextMenuStrip object, you can create its menu items. To do this, as mentioned for the MenuStrip, you can click the first Type Here line, type a string, press Enter, and continue creating the other menu items in the same way.

Unlike a main menu, a popup menu provides a single list of items. If you want different popup menus for your form, you have two options. You can create various popup menus or programmatically change your single popup menu in response to something or some action on your form.

To programmatically create a contextual menu, start by declaring a variable of type ContextMenuStrip. Here is an example:

using System.Windows.Forms;

public class Exercise : Form
{
    public Exercise()
    {
        InitializeComponent();
    }

    void InitializeComponent()
    {
        System.Windows.Forms.ContextMenuStrip context =
		new System.Windows.Forms.ContextMenuStrip();
    }

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

To assist you with each item of a contextual menu, ToolStrip, the ancestor to the ContextMenuStrip class, is equipped with a property named Items. This property is of type ToolStripItemCollection.

To create one or more menu items, you can use the various techniques we reviewed for the main menu. Here are examples:

void InitializeComponent()
{
    System.Windows.Forms.ContextMenuStrip context =
	new System.Windows.Forms.ContextMenuStrip();

    ToolStripMenuItem mnuCut = new ToolStripMenuItem("Cut");

    ToolStripMenuItem[] mnuEdit =
    {
	    new ToolStripMenuItem("Copy"),
	    new ToolStripMenuItem("Paste")
    };
}

After creating a menu item, to add it to the contextual menu, you can call the ToolStripItemCollection.Add() method. To add an array of items, you can call the ToolStripItemCollection.AddRange() method. Here are examples:

void InitializeComponent()
{
    System.Windows.Forms.ContextMenuStrip context =
	new System.Windows.Forms.ContextMenuStrip();

    ToolStripMenuItem mnuCut = new ToolStripMenuItem("Cut");
    ToolStripMenuItem[] mnuEdit =
    {
		new ToolStripMenuItem("Copy"),
        new ToolStripMenuItem("Paste")
    };

    context.Items.Add(mnuCut);
    context.Items.AddRange(mnuEdit);
}

Using a Contextual Menu

By default, a newly created contextual menu is attached neither to the form nor to any control on it. In order to display a context menu, you must assign its name to the control. To support this, Control, the ancestor to all visual controls of the .NET Framework, is equipped, and provides to its children, with a property named ContextMenuStrip, which is of type ContextMenuStrip.

To visually assign a contextual menu to a control during design, click the control. In the Properties window, click the ContextMenuStrip field, then click the arrow of its combo box, and select the menu. If you had created more than one contextual menu, the combo box would show all of them and you can choose the one you want to use as default.

To programmatically specify the contextual menu of a control, assign a ContextMenuStrip object to its ContextMenuStrip property. Here is an example:

void InitializeComponent()
{
    System.Windows.Forms.ContextMenuStrip context =	new System.Windows.Forms.ContextMenuStrip();

    ToolStripMenuItem mnuCut = new ToolStripMenuItem("Cut");
    ToolStripMenuItem[] mnuEdit =
    {
		new ToolStripMenuItem("Copy"),
	        new ToolStripMenuItem("Paste")
    };

    context.Items.Add(mnuCut);
    context.Items.AddRange(mnuEdit);

    ContextMenuStrip = context;
}

After assigning a ContextMenuStrip object to a control, when you right-click (actually when the user right-clicks) the control, the contextual menu would display. The above code would produce:

In your application, you can create as many contextual menus as you want. If you have different controls, each can have its own contextual menu or many can share a contextual menu. Also, you can use different contextual menus for a control and decide what menu to display when/why.

Practical Learning: Creating Contextual Menu

1. In the Menus & Toolbars section of the Toolbox, click ContextMenuStrip
2. Click an unoccupied area of the form
3. In the Properties window, change the (Name) to cmsDirectory
4. Still in the Properties window, click Items and click its button
5. Using the Add button, create three items as follows:

   Text	(Name)
   New Auto-Part	miNewAutoPart
   Edit Store Item	miEditAutoPart
   Delete Inventory Item	miDeleteAutoPart

6. On the Items Collection Editor dialog box, click OK
7. On the form, click the tree view
8. In the Properties window, click ContextMenuStrip, then click the arrow of its combo box and select cmsDirectory
9. In the Menus & Toolbars section of the Toolbox, click ContextMenuStrip
10. Click an unoccupied area of the form
11. In the Properties window, change the (Name) to cmsAvailableParts
12. Still in the Properties window, click Items and click its button
13. Using the Add button, create three items as follows:

    Text	(Name)
    New Auto-Part	miNewStoreItem
    Edit Store Item	miEditStoreItem
    Delete Inventory Item	miDeleteStoreItem

14. On the Items Collection Editor dialog box, click OK
15. On the form, click the list view
16. In the Properties window, click ContextMenuStrip, then click the arrow of its combo box and select cmsAvailableParts

Writing Code for a Contextual Menu

There is nothing particularly specific with writing code for a popup menu item. You approach it exactly as if you were dealing with a menu item of a main menu. You can write code for an item of a popup menu independent of any other item of a main menu. If you want an item of a popup menu to respond to the same request as an item of a main menu, you can write code for one of the menu items (either the item on the main menu or the item on the popup menu) and simply call its Click event in the event of the other menu item.

Practical Learning: Preparing Code for Menu Items

1. Below the form, click msMainMenu
2. On the form, click File and double-click New Auto Part
3. Return to the form
4. On the form, click Edit and double-click Update Auto Part
5. Return to the form and, below Update Auto Part, double-click Delete Auto Part
6. Return to the form
7. Below the form, click cmsDirectory
8. On the form, under ContextMenuStrip, double-click New Auto Part
9. Return to the form
10. Below the form, click cmsAvailableParts
11. On the form, under ContextMenuStrip, double-click New Auto Part
12. Return to the form
13. On the form, under ContextMenuStrip and under New Auto Part, double-click Edit Auto Part
14. Return to the form
15. On the form, under ContextMenuStrip and under Edit Auto Part, double-click Delete Auto Part
16. Return to the form
17. On the form, click Help and double-click CPAP
18. Return to the form
19. On the form, click File and double-click Exit
20. Change the document as follows:

    using AutoPartsInventory3.Models;
    
    namespace AutoPartsInventory3
    {
        public partial class CollegeParkAutoParts : Form
        {
            int level = 0;
            int yearSelected = -1;
            string makeSelected = string.Empty;
            string modelSelected = string.Empty;
            string categorySelected = string.Empty;
            ListViewItem lviSelected = new();
    
            public CollegeParkAutoParts()
            {
                InitializeComponent();
            }
    
            private static int GetFirst0Index(string[] objects)
            {
                for (int i = 0; i < objects.Length; i++)
                {
                    if (string.IsNullOrEmpty(objects[i]))
                    {
                        return i;
                    }
                }
    
                return 0;
            }
    
            private void InitializeAutoParts()
            {
                tvwAutoParts.Nodes.Clear();
    
                TreeNode nodRoot = tvwAutoParts.Nodes.Add("College Park Auto-Parts",
                                                          "College Park Auto-Parts", 0, 1);
    
                nodRoot.Nodes.Add("2024", "2024", 2, 3);
                nodRoot.Nodes.Add("2023", "2023", 2, 3);
                nodRoot.Nodes.Add("2022", "2022", 2, 3);
                nodRoot.Nodes.Add("2021", "2021", 2, 3);
                nodRoot.Nodes.Add("2020", "2020", 2, 3);
                nodRoot.Nodes.Add("2019", "2019", 2, 3);
                nodRoot.Nodes.Add("2018", "2018", 2, 3);
                nodRoot.Nodes.Add("2017", "2017", 2, 3);
                nodRoot.Nodes.Add("2016", "2016", 2, 3);
                nodRoot.Nodes.Add("2015", "2015", 2, 3);
                nodRoot.Nodes.Add("2014", "2014", 2, 3);
                nodRoot.Nodes.Add("2013", "2013", 2, 3);
                nodRoot.Nodes.Add("2012", "2012", 2, 3);
                nodRoot.Nodes.Add("2011", "2011", 2, 3);
                nodRoot.Nodes.Add("2010", "2010", 2, 3);
                nodRoot.Nodes.Add("2009", "2009", 2, 3);
                nodRoot.Nodes.Add("2008", "2008", 2, 3);
                nodRoot.Nodes.Add("2007", "2007", 2, 3);
                nodRoot.Nodes.Add("2006", "2006", 2, 3);
                nodRoot.Nodes.Add("2005", "2005", 2, 3);
                nodRoot.Nodes.Add("2004", "2004", 2, 3);
                nodRoot.Nodes.Add("2003", "2003", 2, 3);
                nodRoot.Nodes.Add("2002", "2002", 2, 3);
                nodRoot.Nodes.Add("2001", "2001", 2, 3);
                nodRoot.Nodes.Add("2000", "2000", 2, 3);
    
                // Select the root node
                tvwAutoParts.SelectedNode = nodRoot;
                // Expand the root node
                tvwAutoParts.ExpandAll();
    
                // Check every node year in the tree view
                foreach (TreeNode nodYear in nodRoot.Nodes)
                {
                    ComboBox cbxMakes = new();
    
                    foreach (AutoPart part in Repository.AutoParts)
                    {
                        if (nodYear.Text == part.CarYear.ToString())
                        {
                            if (!cbxMakes.Items.Contains(part.Make))
                                cbxMakes.Items.Add(part.Make!);
                        }
                    }
    
                    foreach (string strMake in cbxMakes.Items)
                        nodYear.Nodes.Add(strMake, strMake, 4, 5);
                }
    
                foreach (TreeNode nodYear in nodRoot.Nodes)
                {
                    foreach (TreeNode nodMake in nodYear.Nodes)
                    {
                        ComboBox cbxModels = new();
    
                        foreach (AutoPart part in Repository.AutoParts)
                        {
                            if ((nodYear.Text == part.CarYear.ToString()) &&
                                (nodMake.Text == part.Make))
                            {
                                if (!cbxModels.Items.Contains(part.Model!))
                                    cbxModels.Items.Add(part.Model!);
                            }
                        }
    
                        foreach (string strModel in cbxModels.Items)
                            nodMake.Nodes.Add(strModel, strModel, 6, 7);
                    }
                }
    
                foreach (TreeNode nodYear in nodRoot.Nodes)
                {
                    foreach (TreeNode nodMake in nodYear.Nodes)
                    {
                        foreach (TreeNode nodModel in nodMake.Nodes)
                        {
                            var cbxCategories = new ComboBox();
    
                            foreach (AutoPart part in Repository.AutoParts)
                            {
                                if ((nodYear.Text == part.CarYear.ToString()) &&
                                    (nodMake.Text == part.Make) &&
                                    (nodModel.Text == part.Model))
                                {
                                    if (!cbxCategories.Items.Contains(part.Category!))
                                        cbxCategories.Items.Add(part.Category!);
                                }
                            }
    
                            foreach (string strCategory in cbxCategories.Items)
                                nodModel.Nodes.Add(strCategory, strCategory, 8, 9);
                        }
                    }
                }
    
                pbxAutoPart.Image = Image.FromFile(@"E:\College Park Auto-Parts\Generic.png");
    
                lvwAutoParts.Items.Clear();
            }
    
            private void CollegeParkAutoParts_Load(object sender, EventArgs e)
            {
                InitializeAutoParts();
            }
    
            private void tvwAutoParts_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
            {
                TreeNode nodClicked = e.Node;
    
                level = nodClicked.Level;
    
                tvwAutoParts.SelectedNode = e.Node;
    
                if (e.Node.Level == 1)
                {
                    yearSelected = Convert.ToInt32(e.Node.Text);
                    makeSelected = string.Empty;
                    modelSelected = string.Empty;
                    categorySelected = string.Empty;
                }
                else if (e.Node.Level == 2)
                {
                    makeSelected = e.Node.Text;
                    yearSelected = Convert.ToInt32(e.Node.Parent.Text);
                    modelSelected = string.Empty;
                    categorySelected = string.Empty;
                }
                else if (e.Node.Level == 3)
                {
                    modelSelected = e.Node.Text;
                    makeSelected = e.Node.Parent.Text;
                    yearSelected = Convert.ToInt32(e.Node.Parent.Parent.Text);
                    categorySelected = string.Empty;
                }
                else if (e.Node.Level == 4)
                {
                    categorySelected = e.Node.Text;
                    modelSelected = e.Node.Parent.Text;
                    makeSelected = e.Node.Parent.Parent.Text;
                    yearSelected = Convert.ToInt32(e.Node.Parent.Parent.Parent.Text);
    
                    lvwAutoParts.Items.Clear();
                }
    
                try
                {
                    foreach (AutoPart part in Repository.AutoParts)
                    {
                        if ((part.Category == nodClicked.Text) &&
                            (part.Model == nodClicked.Parent.Text) &&
                            (part.Make == nodClicked.Parent.Parent.Text) &&
                            (part.CarYear.ToString() == nodClicked.Parent.Parent.Parent.Text))
                        {
                            ListViewItem lviAutoPart = new ListViewItem(part.PartNumber.ToString());
    
                            lviAutoPart.SubItems.Add(part.PartName);
                            lviAutoPart.SubItems.Add(part.UnitPrice.ToString("F"));
                            lvwAutoParts.Items.Add(lviAutoPart);
                        }
                    }
                }
                catch (NullReferenceException)
                {
                }
            }
    
            private void lvwAutoParts_ItemSelectionChanged(object sender, ListViewItemSelectionChangedEventArgs e)
            {
                foreach (AutoPart part in Repository.AutoParts)
                {
                    if (part.PartNumber == long.Parse(e.Item!.Text))
                    {
                        pbxAutoPart.Image = Image.FromFile(@"E:\College Park Auto-Parts\" + part.PartNumber + ".png");
    
                        Width = pbxAutoPart.Left + pbxAutoPart.Image.Width + 40;
                        Height = pbxAutoPart.Top + pbxAutoPart.Image.Height + 80;
                    }
                }
    
                if (lvwAutoParts.SelectedItems.Count == 1)
                    lviSelected = lvwAutoParts.SelectedItems[0];
            }
    
            private void miFileNewAutoPart_Click(object sender, EventArgs e)
            {
                AutoPartNew sin = new AutoPartNew();
    
                sin.ShowDialog();
    
                InitializeAutoParts();
            }
    
            private void miEditUpdateAutoPart_Click(object sender, EventArgs e)
            {
                AutoPartEditor editor = new AutoPartEditor();
    
                editor.ShowDialog();
    
                InitializeAutoParts();
            }
    
            private void miEditDeleteAutoPart_Click(object sender, EventArgs e)
            {
                AutoPartDelete apd = new AutoPartDelete();
    
                apd.ShowDialog();
                InitializeAutoParts();
            }
    
            private void miNewAutoPart_Click(object sender, EventArgs e)
            {
                AutoPartNew sin = new();
    
                sin.InitializeStoreItem();
                sin.ShowDialog();
    
                InitializeAutoParts();
            }
    
            private void miNewStoreItem_Click(object sender, EventArgs e)
            {
                AutoPartNew sin = new();
    
                sin.cbxYears.Text = yearSelected.ToString();
                sin.cbxMakes.Text = makeSelected;
                sin.txtModel.Text = modelSelected;
                sin.cbxCategories.Text = categorySelected;
    
                sin.InitializeStoreItem();
    
                sin.ShowDialog();
    
                InitializeAutoParts();
            }
    
            private void miEditStoreItem_Click(object sender, EventArgs e)
            {
                AutoPartDelete apd = new AutoPartDelete();
    
                apd.ShowDialog();
                InitializeAutoParts();
            }
    
            private void miDeleteStoreItem_Click(object sender, EventArgs e)
            {
                AutoPartDelete apd = new AutoPartDelete();
    
                foreach (AutoPart part in Repository.AutoParts)
                {
                    if (part.PartNumber == int.Parse(lviSelected.Text))
                    {
                        apd.txtPartNumber.Text = part.PartNumber.ToString();
                        apd.txtYear.Text = part.CarYear.ToString();
                        apd.txtMake.Text = part.Make;
                        apd.txtModel.Text = part.Model;
                        apd.txtCategory.Text = part.Category;
                        apd.txtPartName.Text = part.PartName;
                        apd.txtUnitPrice.Text = part.UnitPrice.ToString();
                        break;
                    }
                }
    
                apd.ResizeFormBasedOnPictureBox();
                apd.ShowDialog();
    
                InitializeAutoParts();
            }
    
            private void miHelpAbout_Click(object sender, EventArgs e)
            {
                AboutCPAP about = new AboutCPAP();
                about.ShowDialog();
            }
    
            private void miFileExit_Click(object sender, EventArgs e)
            {
                Close();
            }
        }
    }

21. To execute, on the main menu, click Debug -> Start Without Debugging
22. Close the form and return to your programming environment
23. Close your programming environment

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