Introduction to the Class to Manage Arrays

Overview

To assist with the use and management of arrays, you can combine the array features of the C# language and support from the .NET Framework. As mentioned already, to support arrays, the .NET Framework provides the Array class that is defined in the System namespace of the mscorlib.dll assembly.

When you create an array in C# code, whether an array of primitive values or an array of objects, you are in fact declaring a variable of type Array. Based on this, since an array variable is an object of a class type, you can use the characteristics of the Array class to create an array and/or to manipulate the values stored in the variable. You can create an array using any of the techniques we saw in the previous lessons, or you can use the Array class.

Practical Learning: Introducing Arrays and Classes

1. Start Microsoft Visual Studio
2. On the main menu, click File -> New -> Project...
3. In the middle list, click ASP.NET Web Application (.NET Framework).
   Change the Name of the project to CountriesStatistics06
4. Click OK
5. In the templates list of the New ASP.NET Web Application dialog box, click the MVC icon and click OK
6. In the Solution Explorer, right-click Models -> Add -> New Item...
7. In the left frame of the Add New Item dialog box, click Code and, in the middle frame, click Interface
8. Change the Name to Abbreviated
9. Click Add
10. Create a string-based property as follows:

    namespace CountriesStatistics06.Models
    {
        interface IAbbreviated
        {
            string Abbreviation { get; set; }
        }
    }
    

11. In the Solution Explorer, right-click Models -> Add -> Interface
12. Type GovernmentEntity as the name of the file
13. Click OK
14. Change the class as follows:

    namespace CountriesStatistics06.Models
    {
        interface IGovernmentEntity
        {
            string Name    { get; set; }
            int    Area    { get;      }
            string Capital { get; set; }
        }
    }

15. In the Solution Explorer, right-click Models -> Add -> Class...
16. Change the file Name to Region as the Name of the class
17. Click Add
18. Change the document as follows:

    namespace CountriesStatistics06.Controllers
    {
        public class Region
        {
            public string Designation { get; set; }
            public string Description { get; set; }
        }
    }

19. In the Solution Explorer, right-click Models -> Add -> Class...
20. Type State as the name of the file
21. Press Enter
22. Change the class as follows:

    namespace CountriesStatistics06.Models
    {
        public class State : IGovernmentEntity,
    						   IAbbreviated
                             
        {
            // From the IAbbreviated interface
            public string Abbreviation { get; set; }
    
            // From the IGovernmentEntity interface
            public string Name         { get; set; }
            public int    Area         { get; set; }
            public string Capital      { get; set; }
    
            // New Properties
            public string StateName    => Name;
            public int    AreaSqrMiles => Area;
            public int    AreaSqrKms   { get; set; }
            public Region Region       { get; set; }
    
            public override bool Equals(object obj)
            {
                State stt = (State)obj;
    
                if (stt.Name == Name)
                    return true;
    
                return false;
            }
    
            public override int GetHashCode()
            {
                return base.GetHashCode();
            }
        }
    }

23. In the Solution Explorer, right-click Models -> Add -> Class...
24. Type Federation
25. Click Add
26. Here is an example:

    using System;
    
    namespace CountriesStatistics06.Models
    {
        public class Federation : State
        {
            public int      AdmissionUnionOrder { get; set; }
        }
    }

27. In the Solution Explorer, right-click Content -> Add -> Style Sheet
28. Type CountriesStatistics as the name of the file
29. Click OK
30. Create the following styles in the document:

    body {
        background-color: white;
    }
    
    .navbar-inverse {
        background-color: #8d3434;
        border-bottom:    5px solid black; }
    
    .centralizer {
        margin: auto;
        width:  710px; }
    
    .tblStates {
        margin: auto;
        width:  320px; }
    
    .tblStates table { width: 100%; }

31. In the Solution Explorer, right-click Controllers -> Add -> New Scaffolded Item...
32. In the middle frame of the Add Scaffold dialog box, click MVC 5 Controller - Empty
33. Click Add
34. Type UnitedStates to get UnitedStatesController
35. Click Add
36. Change the class as follows:

    using System;
    using System.Web.Mvc;
    
    namespace CountriesStatistics06.Models
    {
        public class UnitedStatesController : Controller
        {
            // GET: UnitedStates
            public ActionResult Index()
            {
                return View();
            }
    
            // GET: UnitedStates/GeographicDivisions
            public ActionResult GeographicDivisions()
            {
                return View();
            }
        }
    }

37. In the Solution Explorer, under Views, expand Shared and double-click _Layout.cshtml
38. Change the document as follows:

    <!DOCTYPE html>
    <html>
    <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Countries Statistics :: @ViewBag.Title</title>
    @Styles.Render("~/Content/css")
    @Scripts.Render("~/bundles/modernizr")
    <link rel="stylesheet" type="text/css" href="~/Content/CountriesStatistics.css" />
    </head>
    <body>
        <div class="navbar navbar-inverse navbar-fixed-top">
            <div class="container">
                <div class="navbar-header">
                    <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                        <span class="icon-bar"></span>
                    </button>
                    @Html.ActionLink("Countries Statistics", "Index", "Home", new { area = "" }, new { @class = "navbar-brand" })
                </div>
    
                <div class="navbar-collapse collapse">
                    <ul class="nav navbar-nav">
                        <li>@Html.ActionLink("The World", "Index", "Home")</li>
                        <li>@Html.ActionLink("Oceans", "Oceans", "Home")</li>
                        <li>@Html.ActionLink("Continents", "Continents", "Home")</li>
                        <li>@Html.ActionLink("Flags", "Flags", "Home")</li>
                        <li>@Html.ActionLink("Maps", "Maps", "Home")</li>
                        <li>@Html.ActionLink("Historical Figures", "Historical", "Home")</li>
                        <li>@Html.ActionLink("About Us", "About", "Home")</li>
                        <li>@Html.ActionLink("Contact Us", "Contact", "Home")</li>
                    </ul>
                </div>
            </div>
        </div>
    
        <div class="container body-content">
            @RenderBody()
        </div>
    
        <footer class="navbar-fixed-bottom">
            <h4 class="text-center colorized">&copy; @DateTime.Now.Year - Countries Statistics</h4>
        </footer>
    
        @Scripts.Render("~/bundles/jquery")
        @Scripts.Render("~/bundles/bootstrap")
        @RenderSection("scripts", required: false)
    </body>
    </html>

39. In the Solution Explorer, under Controllers, double-click UnitedStatesController.cs to acces it

Creating an Array

To assist you with creating an array, the Array class is equipped with a method named CreateInstance() that comes in various versions. To create a one-dimensional array whose members are zero-based, you can use the following version:

public static Array CreateInstance(Type elementType, int length);

The first argument is used to specify the type of array you want to create. You are allowed to create an array of any type, that is, an array of primitive values or an array of objects. The first argument is declared as Type. This means that it can be anything. For this reason, you can use the typeof operator to cast your type. Therefore, pass the type or the class in the parentheses of the typeof operator.

The second argument specifies the number of members of the array. Using the Array class, you can create an array as follows:

@{
    ViewBag.Title = "Numbers";
}

<h2>Numbers</h2>

@{
    Array numbers = Array.CreateInstance(typeof(double), length);
}

You can also use the var or the b>dynamic keyword to declare the variable. Here is an example:

@{
    var numbers = Array.CreateInstance(typeof(double), 5);
}

Practical Learning: Creating an Array

• To start some arrays, declare two array variables and initialize them as follows:

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Web;
  using System.Web.Mvc;
  
  namespace CountriesStatistics06.Models
  {
      public class UnitedStatesController : Controller
      {
          public Array States;
          public Array Regions;
  
          public UnitedStatesController()
          {
              Regions = Array.CreateInstance(typeof(Models.Region), 9);
              States  = Array.CreateInstance(typeof(Models.Federation), 30);
          }
  
          // GET: UnitedStates
          public ActionResult Index()
          {
              return View();
          }
      }
  }

The Length of an Array

We know that if you declare a variable for an array but don't initialize it, you must specify the number of elements of the array. Here is an example:

@{
    double[] numbers = new double[5];
}

If you use the Array class to create an array, you must pass this constant integer as the second argument of the CreateInstance() method from the the above version. Here is an example:

@{
    var numbers = Array.CreateInstance(typeof(double), 5);
}

If the array exists already, that is, if you have already created the array or you are using an array created by someone else, to find out the number of items it contains, you can access its Length property. Therefore, the length of an array is the number of elements it contains.

Alternatively, you can call the Array.GetLength() method. Its syntax is:

public int GetLength(int dimension);

For a one-dimensional array, you must pass the argument as 0. This method returns an integer that represents the number of items in the array.

The Rank of an Array

We have seen that the square brackets are used to specify that you are declaring an array. If you are creating a one-dimensional array, we saw that you could type a number in the square bracket. If you are creating a two-dimensional array, you type two numbers separated by a comma in the second pair of square brackets. Each number, whether it is one, two, or more is a placeholder for what is referred to as a dimension. In other words, a one dimensional array has a dimension of one. A two-dimensional array has a dimension of 2, and so on.

To find out the dimension of an array, the Array class provides the Rank property. Therefore, to know the dimension of an existing array, you can access its Rank property.

Fundamental Operations on an Array

Adding a Value to an Array

We know that, to initialize an array, you can open the curly brackets and list its members separated by commas, or you could access each member and assign it the desired value. To support the ability to add members to an array, the Array class is equipped with a method named SetValue that comes in different versions. To add a new item to the types of arrays we have used so far, you can call the following version of the Array.SetValue() method:

public void SetValue(object value, int index);

The first argument is the value to add to the list. The second argument is the index of the member to be added. The first item has index 1; the second item has index 2, and so on. If the array is a list of primitive values, simply pass the value for the first argument. Here are examples of calling the method:

@{ 
    Array numbers = Array.CreateInstance(typeof(double), 5);

    numbers.SetValue(7628.937, 0);
    numbers.SetValue(6.48, 1);
    numbers.SetValue(574.9, 2);
    numbers.SetValue(293749.064, 3);
    numbers.SetValue(0.70257, 4);
}

If the array is a list of objects, use any technique to create an object and pass it as the first argument. Here are examples:

@{
    Array elements = Array.CreateInstance(typeof(Element), 5);

    Element K = new Element();
    K.Symbol = "K";
    K.AtomicNumber = 19;
    K.ElementName = "Potassium";
    K.AtomicWeight = 39.098f;

    Element Ca = new Element(20);
    Element Sc = new Element("Sc");
    Element Ti = new Element(22, "Ti", "Titanium", 47.867F);

    elements.SetValue(K, 0);
    elements.SetValue(Ca, 1);
    elements.SetValue(Sc, 2);
    elements.SetValue(Ti, 3);
    elements.SetValue(new Element(23), 4);
    elements.SetValue(new Element(24, "Cr", "Chromium", 51.996F), 5);
}

We indicated that whenever you create an array, you are in fact declaring an instance of the Array class. Therefore, even if you create an array using the square bracket formula, you can still call the SetValue() method to specify any member of the array. Here is an example:

@{
    var numbers = new double[5];

    numbers.SetValue(7628.937, 0);
    numbers.SetValue(6.48, 1);
    numbers.SetValue(574.9, 2);
    numbers.SetValue(293749.064, 3);
    numbers.SetValue(0.70257, 4);
}

The Array class provides a SetValue() version for each corresponding CreateInstance() method we reviewed earlier.

Practical Learning: Adding Objects to an Array

• To initialize the array, add the following code:

  using System;
  using System.Web.Mvc;
  
  namespace CountriesStatistics06.Models
  {
      public class UnitedStatesController : Controller
      {
          public Array States;
          public Array Regions;
  
          public UnitedStatesController()
          {
              Regions = Array.CreateInstance(typeof(Models.Region), 9);
              States  = Array.CreateInstance(typeof(Models.Federation), 30);
  
              Regions.SetValue(new Models.Region() { Designation = "East North Central", Description = "The East North Central region includes the states around the Great Lakes." }, 1);
              Regions.SetValue(new Models.Region() { Designation = "East South Central", Description = "The East South Central portion is one of the regions designated as the South." }, 2);
              Regions.SetValue(new Models.Region() { Designation = "New England", Description = "New England is the group of states in the North-East region. It is delimited in the North and North-East by Canada, in the East by the Atlantic Ocean, and in the South and West by the New York state." }, 3);
              Regions.SetValue(new Models.Region() { Designation = "Mid-Atlantic", Description = "Mid-Atlantic is a region situated in the south of New England. Mid-Atlantic is one of the regions defined by the Census bureau for statistical purposes." }, 4);
              Regions.SetValue(new Models.Region() { Designation = "Mountain", Description = "Like the name suggests, the Mountain region covers states known for their mountaneous characteristics. They are also covered by desertic areas." }, 5);
              Regions.SetValue(new Models.Region() { Designation = "Pacific", Description = "The Pacific region covers the costal western states plus the two non-continental states of Alaska and the Hawaiian islands. All states in this region have a coast on the Pacific Ocean." }, 6);
              Regions.SetValue(new Models.Region() { Designation = "South Atlantic", Description = "The South Atlantic region includes the states in the South-East part but also counts the Disctrict of Columbia." }, 7);
              Regions.SetValue(new Models.Region() { Designation = "West North Central", Description = "The West North Central region includes the states in the Great Planes area. This reqion is divided from the East North Central part by the Mississippi River. This region is characterized by vast agricultural farms and high employment." }, 8);
              Regions.SetValue(new Models.Region() { Designation = "West South Central", Description = "The West South Central part is one of the regions with (only) four states. The imposing Texas state is both the largest and the most populous state in the region." }, 9);        
          }
  
          // GET: Venezuela
          public ActionResult Index()
          {
              return View();
          }
      }
  }

Getting a Value from an Array

To support the ability to retrieve the value of a member of an array, the Array class is equipped with a method named GetValue that is overloaded with a version corresponding to each version of the CreateInstance() and the SetValue() methods. For example, to access the values stored in a one-dimensional array, you can call this version:

public object GetValue(int index);

The index argument is the zero-based index of the member whose value you want to access. If the array is a list of primitive values, the Array.GetValue() method directly produces the value stored in the indicated position. Here is an example:

@{
    var numbers = new double[5];

    numbers.SetValue(7628.937, 0);
    numbers.SetValue(6.48, 1);
    numbers.SetValue(574.9, 2);
    numbers.SetValue(293749.064, 3);
    numbers.SetValue(0.70257, 4);
}

<p>Number: @numbers.GetValue(0)</p>
}

Notice that the Array.GetValue() returns an anonymous object. This means that it can return anything. Therefore, if the array you are using is a list of objects, you must cast the returned object to the appropriate class. Here is an example:

@{
    Array elements = Array.CreateInstance(typeof(Element), 5);

    Element K = new Element();
    K.Symbol = "K";
    K.AtomicNumber = 19;
    K.ElementName = "Potassium";
    K.AtomicWeight = 39.098f;

    Element Ca = new Element(20);
    Element Sc = new Element("Sc");
    Element Ti = new Element(22, "Ti", "Titanium", 47.867F);

    elements.SetValue(K, 0);
    elements.SetValue(Ca, 1);
    elements.SetValue(Sc, 2);
    elements.SetValue(Ti, 3);
    elements.SetValue(new Element(23), 4);
    elements.SetValue(new Element(24, "Cr", "Chromium", 51.996F), 5);
}

@{ 
    Element elm = (Element)elements.GetValue(2);
}

When calling the Array.GetValue() method, if you pass an invalid value, the webpage would throw an exception.

Practical Learning: Getting the Objects of an Arrray

1. Create another array as follows:

   using System;
   using System.Web.Mvc;
   
   namespace CountriesStatistics06.Controllers
   {
       public class UnitedStatesController : Controller
       {
           public Array States;
           public Array Regions;
   
           public UnitedStatesController()
           {
               Regions = Array.CreateInstance(typeof(Models.Region), 9);
               States  = Array.CreateInstance(typeof(Models.Federation), 30);
   
               Regions.SetValue(new Models.Region() { Designation = "East North Central", Description = "The East North Central region includes the states around the Great Lakes." }, 0);
               Regions.SetValue(new Models.Region() { Designation = "East South Central", Description = "The East South Central portion is one of the regions designated as the South." }, 1);
               Regions.SetValue(new Models.Region() { Designation = "New England",        Description = "New England is the group of states in the North-East region. It is delimited in the North and North-East by Canada, in the East by the Atlantic Ocean, and in the South and West by the New York state." }, 2);
               Regions.SetValue(new Models.Region() { Designation = "Mid-Atlantic",       Description = "Mid-Atlantic is a region situated in the south of New England. Mid-Atlantic is one of the regions defined by the Census bureau for statistical purposes." }, 3);
               Regions.SetValue(new Models.Region() { Designation = "Mountain",           Description = "Like the name suggests, the Mountain region covers states known for their mountaneous characteristics. They are also covered by desertic areas." }, 4);
               Regions.SetValue(new Models.Region() { Designation = "Pacific",            Description = "The Pacific region covers the costal western states plus the two non-continental states of Alaska and the Hawaiian islands. All states in this region have a coast on the Pacific Ocean." }, 5);
               Regions.SetValue(new Models.Region() { Designation = "South Atlantic",     Description = "The South Atlantic region includes the states in the South-East part but also counts the Disctrict of Columbia." }, 6);
               Regions.SetValue(new Models.Region() { Designation = "West North Central", Description = "The West North Central region includes the states in the Great Planes area. This reqion is divided from the East North Central part by the Mississippi River. This region is characterized by vast agricultural farms and high employment." }, 7);
               Regions.SetValue(new Models.Region() { Designation = "West South Central", Description = "The West South Central part is one of the regions with (only) four states. The imposing Texas state is both the largest and the most populous state in the region." }, 8);
   
                States.SetValue(new Models.Federation() { Abbreviation = "RI", Name = "Rhode Island",   Area =   1545, AreaSqrKms =    4002, AdmissionUnionOrder = 13, Capital = "Providence",     Region = (Models.Region)(Regions.GetValue(2)) },  0);
               States.SetValue(new Models.Federation() { Abbreviation = "OH", Name = "Ohio",           Area =  44828, AreaSqrKms =  116103, AdmissionUnionOrder = 17, Capital = "Columbus",       Region = (Models.Region)(Regions.GetValue(0)) },  1);
               States.SetValue(new Models.Federation() { Abbreviation = "KY", Name = "Kentucky",       Area =  40411, AreaSqrKms =  104665, AdmissionUnionOrder = 15, Capital = "Frankfort",      Region = (Models.Region)(Regions.GetValue(1)) },  2);
               States.SetValue(new Models.Federation() { Abbreviation = "IA", Name = "Iowa",           Area =  56276, AreaSqrKms =  145754, AdmissionUnionOrder = 29, Capital = "Des Moines",     Region = (Models.Region)(Regions.GetValue(7)) },  3);
               States.SetValue(new Models.Federation() { Abbreviation = "WI", Name = "Wisconsin",      Area =  65503, AreaSqrKms =  169653, AdmissionUnionOrder = 30, Capital = "Madison",        Region = (Models.Region)(Regions.GetValue(0)) },  4);
               States.SetValue(new Models.Federation() { Abbreviation = "VT", Name = "Vermont",        Area =   9615, AreaSqrKms =   24903, AdmissionUnionOrder = 14, Capital = "Montpelier",     Region = (Models.Region)(Regions.GetValue(2)) },  5);
               States.SetValue(new Models.Federation() { Abbreviation = "ID", Name = "Idaho",          Area =  83574, AreaSqrKms =  216456, AdmissionUnionOrder = 43, Capital = "Boise",          Region = (Models.Region)(Regions.GetValue(4)) },  6);
               States.SetValue(new Models.Federation() { Abbreviation = "ME", Name = "Maine",          Area =  35387, AreaSqrKms =   91653, AdmissionUnionOrder = 23, Capital = "Augusta",        Region = (Models.Region)(Regions.GetValue(2)) },  7);
               States.SetValue(new Models.Federation() { Abbreviation = "OR", Name = "Oregon",         Area =  98386, AreaSqrKms =  254819, AdmissionUnionOrder = 33, Capital = "Salem",          Region = (Models.Region)(Regions.GetValue(5)) },  8);
               States.SetValue(new Models.Federation() { Abbreviation = "ND", Name = "North Dakota",   Area =  70704, AreaSqrKms =  183123, AdmissionUnionOrder = 39, Capital = "Bismarck",       Region = (Models.Region)(Regions.GetValue(7)) },  9);
               States.SetValue(new Models.Federation() { Abbreviation = "IN", Name = "Indiana",        Area =  36420, AreaSqrKms =   94328, AdmissionUnionOrder = 19, Capital = "Indianapolis",   Region = (Models.Region)(Regions.GetValue(0)) }, 10);
               States.SetValue(new Models.Federation() { Abbreviation = "MS", Name = "Mississippi",    Area =  48434, AreaSqrKms =  125443, AdmissionUnionOrder = 20, Capital = "Jackson",        Region = (Models.Region)(Regions.GetValue(1)) }, 11);
               States.SetValue(new Models.Federation() { Abbreviation = "TX", Name = "Texas",          Area = 268601, AreaSqrKms =  695676, AdmissionUnionOrder = 28, Capital = "Austin",         Region = (Models.Region)(Regions.GetValue(8)) }, 12);
               States.SetValue(new Models.Federation() { Abbreviation = "MT", Name = "Montana",        Area = 147046, AreaSqrKms =  380850, AdmissionUnionOrder = 41, Capital = "Helena",         Region = (Models.Region)(Regions.GetValue(4)) }, 13);
               States.SetValue(new Models.Federation() { Abbreviation = "NC", Name = "North Carolina", Area =  53821, AreaSqrKms =  139397, AdmissionUnionOrder = 12, Capital = "Raleigh",        Region = (Models.Region)(Regions.GetValue(6)) }, 14);
               States.SetValue(new Models.Federation() { Abbreviation = "TN", Name = "Tennessee",      Area =  42146, AreaSqrKms =  109158, AdmissionUnionOrder = 16, Capital = "Nashville",      Region = (Models.Region)(Regions.GetValue(1)) }, 15);
               States.SetValue(new Models.Federation() { Abbreviation = "NE", Name = "Nebraska",       Area =  77358, AreaSqrKms =  200358, AdmissionUnionOrder = 37, Capital = "Lincoln",        Region = (Models.Region)(Regions.GetValue(7)) }, 16);
               States.SetValue(new Models.Federation() { Abbreviation = "IL", Name = "Illinois",       Area =  57918, AreaSqrKms =  150007, AdmissionUnionOrder = 21, Capital = "Springfield",    Region = (Models.Region)(Regions.GetValue(0)) }, 17);
               States.SetValue(new Models.Federation() { Abbreviation = "KS", Name = "Kansas",         Area =  82282, AreaSqrKms =  213110, AdmissionUnionOrder = 34, Capital = "Topeka",         Region = (Models.Region)(Regions.GetValue(7)) }, 18);
               States.SetValue(new Models.Federation() { Abbreviation = "NH", Name = "New Hampshire",  Area =   9351, AreaSqrKms =   24219, AdmissionUnionOrder =  9, Capital = "Concord",        Region = (Models.Region)(Regions.GetValue(2)) }, 19);
               States.SetValue(new Models.Federation() { Abbreviation = "DE", Name = "Delaware",       Area =   2489, AreaSqrKms =    6447, AdmissionUnionOrder =  1, Capital = "Dover",          Region = (Models.Region)(Regions.GetValue(6)) }, 20);
               States.SetValue(new Models.Federation() { Abbreviation = "NJ", Name = "New Jersey",     Area =   8722, AreaSqrKms =   22590, AdmissionUnionOrder =  3, Capital = "Trenton",        Region = (Models.Region)(Regions.GetValue(3)) }, 21);
               States.SetValue(new Models.Federation() { Abbreviation = "AK", Name = "Alaska",         Area = 656424, AreaSqrKms = 1700139, AdmissionUnionOrder = 49, Capital = "Juneau",         Region = (Models.Region)(Regions.GetValue(5)) }, 22);
               States.SetValue(new Models.Federation() { Abbreviation = "NM", Name = "New Mexico",     Area = 121598, AreaSqrKms =  314939, AdmissionUnionOrder = 47, Capital = "Santa Fe",       Region = (Models.Region)(Regions.GetValue(4)) }, 23);
               States.SetValue(new Models.Federation() { Abbreviation = "NY", Name = "New York",       Area =  54475, AreaSqrKms =  141089, AdmissionUnionOrder = 11, Capital = "Albany",         Region = (Models.Region)(Regions.GetValue(3)) }, 24);
               States.SetValue(new Models.Federation() { Abbreviation = "CA", Name = "California",     Area = 163707, AreaSqrKms =  424002, AdmissionUnionOrder = 31, Capital = "Sacramento",     Region = (Models.Region)(Regions.GetValue(5)) }, 25);
               States.SetValue(new Models.Federation() { Abbreviation = "MO", Name = "Missouri",       Area =  69709, AreaSqrKms =  180546, AdmissionUnionOrder = 24, Capital = "Jefferson City", Region = (Models.Region)(Regions.GetValue(7)) }, 26);
               States.SetValue(new Models.Federation() { Abbreviation = "OK", Name = "Oklahoma",       Area  = 69903, AreaSqrKms =  181049, AdmissionUnionOrder = 46, Capital = "Oklahoma City",  Region = (Models.Region)(Regions.GetValue(8)) }, 27);
               States.SetValue(new Models.Federation() { Abbreviation = "PA", Name = "Pennsylvania",   Area =  46058, AreaSqrKms =  119291, AdmissionUnionOrder =  2, Capital = "Harrisburg",     Region = (Models.Region)(Regions.GetValue(3)) }, 28);
               States.SetValue(new Models.Federation() { Abbreviation = "SC", Name = "South Carolina", Area =  32007, AreaSqrKms =   82898, AdmissionUnionOrder =  8, Capital = "Columbia",       Region = (Models.Region)(Regions.GetValue(6)) }, 29);
           }
   
           // GET: UnitedStates
           public ActionResult Index()
           {
               return View();
           }
   
           // GET: UnitedStates/GeographicDivisions
           public ActionResult GeographicDivisions()
           {
               return View();
           }
       }
   }

2. In the document, right-click Index and click Add View...
3. In the dialog box, click Add

Looping for an Array

To access one member of the array at a time, you can use a loop to access any member using its index. You can use any of the classic three loops: for, while, or do...while. Here is an example that uses a for loop and the Length property to know the number of members of an array:

@{ 
    var numbers = new double[5];

    numbers.SetValue(7628.937, 0);
    numbers.SetValue(6.48, 1);
    numbers.SetValue(574.9, 2);
    numbers.SetValue(293749.064, 3);
    numbers.SetValue(0.70257, 4);
}

@for (int i = 0; i < numbers.Length; i++)
{
    <p>Number: @numbers.GetValue(i)</p>
}

This would produce:

Practical Learning: Looping Through an Arrray of Objects

1. To display the list of states, type the following code:

   @{
       ViewBag.Title = "United States of America";
   }
   
   <h2 class="text-center">United States of America</h2>
   
   @{
       CountriesStatistics06.Controllers.UnitedStatesController usc = new CountriesStatistics06.Controllers.UnitedStatesController();
   }
   
   <table border="6" style="width: 100%" cellpadding="2" cellspacing="1">
       <tr>
           <td>&nbsp;</td>
           <td>&nbsp;</td>
           <td>&nbsp;</td>
           <td colspan="2" class="text-center"><b>Area</b></td>
           <td class="text-center"><b>Admission to Union</b></td>
           <td>&nbsp;</td>
           <td>&nbsp;</td>
       </tr>
       <tr style="border-bottom: 2px solid black;">
           <td class="text-center"><b>#</b></td>
           <td class="text-center"><b>Abbrv</b></td>
           <td class="text-center"><b>State Name</b></td>
           <td class="text-center"><b>Sqr Miles</b></td>
           <td class="text-center"><b>Km<sup>2</sup></b></td>
           <td class="text-center"><b>Order</b></td>
           <td><b>Capital</b></td>
           <td><b>Region</b></td>
       </tr>
   
       @for (int counter = 0; counter <= usc.States.Length - 1; counter++)
       {
           CountriesStatistics06.Models.Federation stt = (CountriesStatistics06.Models.Federation)usc.States.GetValue(counter);
   
           <tr>
               <td class="text-center">@(counter + 1)</td>
               <td class="text-center">@stt.Abbreviation</td>
               <td>@stt.StateName</td>
               <td class="text-right">@stt.AreaSqrMiles</td>
               <td class="text-right">@stt.AreaSqrKms</td>
               <td class="text-center">@stt.AdmissionUnionOrder</td>
               <td>@stt.Capital</td>
               <td>@stt.Region.Designation</td>
           </tr>
       }
   </table>

2. To execute, on the main menu, click Debug -> Start Without Debugging:

   

3. Close the browser and return to your programming environment

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