Routine List-Based Operations on Arrays

Sorting an Array

When accessing the members of an array, you may want them to be arranged in alphabetical, numerical, or chronological order. To assist you with re-arranging the elements in an array, the Array class is equipped with a method named Sort that is overloaded with as many versions as you can possibly need.

To arrange an array, you can call the following version of the Array.Sort() method:

public static void Sort(Array array);

This is a static method that takes as argument the name of the array you want to re-arrange. If your array is a list of primitive values, the sorting operation is automatic. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>
<h1>Numbers</h1>

@{
    double[] numbers = new double[8]
    {
        7628.937, 6.48, 574.9, 293749.064,
        0.70257, 314.905, 80458.01, 28.07
    };
}

<h3>Original List</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

@{  Array.Sort(numbers); }

<h3>Sorted List</h3>

<table>
@foreach (var number in numbers)
{
    <tr>
        <td>Number: @number</td>
    </tr>
}
</table>

</body>
</html>

This would produce:

Sorting the Values of an Array

Notice that the numbers are arranged in in ascending order. In the same way, if the array is made of strings, you can call the Array.Sort() method to arrange the list in alphabetical order. If the array is made of dates, you can arrange them in chronological order.

If your array is a list of objects, the class that constitutes the array must implement the IComparable interface that we introduced already in Lesson 30.

Practical LearningPractical Learning: Sorting an Array of Objects

  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 CountriesStatistics07
  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 CountriesStatistics07.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 CountriesStatistics07.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 CountriesStatistics07.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: 
    using System;

namespace CountriesStatistics07.Models
{
    public class State : IAbbreviated,
                         IGovernmentEntity,
                         IComparable
    {
        // From the IAbbreviated interface
        public string Abbreviation { get; set; }
        // From the IGovernmentEntity interface
        public string Name { get; set; }
        public int Area
        {
            get { return AreaSqrMiles; }
            set { }
        }

        public string Capital { get; set; }

        // New Properties
        public string StateName => Name;
        public int AreaSqrMiles { get; set; }
        public int AreaSqrKms    { get; set; }
        public Region Region    { get; set; }

        public int CompareTo(object stt)
        {
            if (stt == null)
            {
                return 0;
            }

            State other = stt as State;

            if (other != null)
                return StateName.CompareTo(other.StateName);

            return 0;
        }
    }
}
  23. In the Solution Explorer, right-click Models -> Add -> Class...
  24. Type Federation
  25. Click Add
  26. Here is an example: 
    using System;

namespace CountriesStatistics07.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, expand Add_Start and double-click BundleConfig.cs
  32. Change the document as follows: 
    using System.Web.Optimization;

namespace CountriesStatistics07
{
    public class BundleConfig
    {
        // For more information on bundling, visit https://go.microsoft.com/fwlink/?LinkId=301862
        public static void RegisterBundles(BundleCollection bundles)
        {
            bundles.Add(new ScriptBundle("~/bundles/jquery").Include(
                        "~/Scripts/jquery-{version}.js"));

            bundles.Add(new ScriptBundle("~/bundles/jqueryval").Include(
                        "~/Scripts/jquery.validate*"));

            // Use the development version of Modernizr to develop with and learn from. Then, when you're
            // ready for production, use the build tool at https://modernizr.com to pick only the tests you need.
            bundles.Add(new ScriptBundle("~/bundles/modernizr").Include(
                        "~/Scripts/modernizr-*"));

            bundles.Add(new ScriptBundle("~/bundles/bootstrap").Include(
                      "~/Scripts/bootstrap.js"));

            bundles.Add(new StyleBundle("~/Content/css").Include(
                      "~/Content/bootstrap.css",
                      "~/Content/site.css",
                      "~/Content/CountriesStatistics.css"));
        }
    }
}
  33. In the Solution Explorer, right-click Controllers -> Add -> New Scaffolded Item...
  34. In the middle frame of the Add Scaffold dialog box, click MVC 5 Controller - Empty
  35. Click Add
  36. Type UnitedStates to get UnitedStatesController
  37. Click Add
  38. Change the class as follows: 
    using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace CountriesStatistics07.Controllers
{
    public class UnitedStatesController : Controller
    {
        public UnitedStatesController()
        {
        }

        // GET: UnitedStates
        public ActionResult Index()
        {
            return View();
        }

        // GET: UnitedStates/Regions
        public ActionResult Regions()
        {
            return View();
        }

        // GET: UnitedStates/StatesList
        public ActionResult StatesList()
        {
            return View();
        }
    }
}
  39. In the document, right-click Index and click Add View...
  40. In the dialog box, make sure the text box displays Index and click Add
  41. Click Add
  42. Change the document as follows: 
    @{
    ViewBag.Title = "United States of America";
}

<h2 class="text-center">United States of America</h2>

@{
    int counter = 0;

    CountriesStatistics07.Models.Region[] regions = new CountriesStatistics07.Models.Region[]
    {
        new CountriesStatistics07.Models.Region() { Designation = "East North Central", Description = "The East North Central region includes the states around the Great Lakes." },
        new CountriesStatistics07.Models.Region() { Designation = "East South Central", Description = "The East South Central portion is one of the regions designated as the South." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." }
    };

    CountriesStatistics07.Models.Federation[] states = new CountriesStatistics07.Models.Federation[40];

    states[0]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "RI", Name = "Rhode Island",   Area =   1545, AreaSqrKms =    4002, AdmissionUnionOrder = 13, Capital = "Providence",     Region = regions[2] };
    states[1]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "OH", Name = "Ohio",           Area =  44828, AreaSqrKms =  116103, AdmissionUnionOrder = 17, Capital = "Columbus",       Region = regions[0] };
    states[2]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "KY", Name = "Kentucky",       Area =  40411, AreaSqrKms =  104665, AdmissionUnionOrder = 15, Capital = "Frankfort",      Region = regions[2] };
    states[3]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "IA", Name = "Iowa",           Area =  56276, AreaSqrKms =  145754, AdmissionUnionOrder = 29, Capital = "Des Moines",     Region = regions[7] };
    states[4]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "WI", Name = "Wisconsin",      Area =  65503, AreaSqrKms =  169653, AdmissionUnionOrder = 30, Capital = "Madison",        Region = regions[0] };
    states[5]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "VT", Name = "Vermont",        Area =   9615, AreaSqrKms =   24903, AdmissionUnionOrder = 14, Capital = "Montpelier",     Region = regions[2] };
    states[6]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "ID", Name = "Idaho",          Area =  83574, AreaSqrKms =  216456, AdmissionUnionOrder = 43, Capital = "Boise",          Region = regions[4] };
    states[7]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "ME", Name = "Maine",          Area =  35387, AreaSqrKms =   91653, AdmissionUnionOrder = 23, Capital = "Augusta",        Region = regions[2] };
    states[8]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "OR", Name = "Oregon",         Area =  98386, AreaSqrKms =  254819, AdmissionUnionOrder = 33, Capital = "Salem",          Region = regions[5] };
    states[9]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "ND", Name = "North Dakota",   Area =  70704, AreaSqrKms =  183123, AdmissionUnionOrder = 39, Capital = "Bismarck",       Region = regions[7] };
    states[10] = new CountriesStatistics07.Models.Federation() { Abbreviation = "IN", Name = "Indiana",        Area =  36420, AreaSqrKms =   94328, AdmissionUnionOrder = 19, Capital = "Indianapolis",   Region = regions[0] };
    states[11] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MS", Name = "Mississippi",    Area =  48434, AreaSqrKms =  125443, AdmissionUnionOrder = 20, Capital = "Jackson",        Region = regions[1] };
    states[12] = new CountriesStatistics07.Models.Federation() { Abbreviation = "TX", Name = "Texas",          Area = 268601, AreaSqrKms =  695676, AdmissionUnionOrder = 28, Capital = "Austin",         Region = regions[8] };
    states[13] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MT", Name = "Montana",        Area = 147046, AreaSqrKms =  380850, AdmissionUnionOrder = 41, Capital = "Helena",         Region = regions[4] };
    states[14] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NC", Name = "North Carolina", Area =  53821, AreaSqrKms =  139397, AdmissionUnionOrder = 12, Capital = "Raleigh",        Region = regions[6] };
    states[15] = new CountriesStatistics07.Models.Federation() { Abbreviation = "TN", Name = "Tennessee",      Area =  42146, AreaSqrKms =  109158, AdmissionUnionOrder = 16, Capital = "Nashville",      Region = regions[1] };
    states[16] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NE", Name = "Nebraska",       Area =  77358, AreaSqrKms =  200358, AdmissionUnionOrder = 37, Capital = "Lincoln",        Region = regions[7] };
    states[17] = new CountriesStatistics07.Models.Federation() { Abbreviation = "IL", Name = "Illinois",       Area =  57918, AreaSqrKms =  150007, AdmissionUnionOrder = 21, Capital = "Springfield",    Region = regions[0] };
    states[18] = new CountriesStatistics07.Models.Federation() { Abbreviation = "KS", Name = "Kansas",         Area =  82282, AreaSqrKms =  213110, AdmissionUnionOrder = 34, Capital = "Topeka",         Region = regions[7] };
    states[19] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NH", Name = "New Hampshire",  Area =   9351, AreaSqrKms =   24219, AdmissionUnionOrder =  9, Capital = "Concord",        Region = regions[2] };
    states[20] = new CountriesStatistics07.Models.Federation() { Abbreviation = "DE", Name = "Delaware",       Area =   2489, AreaSqrKms =    6447, AdmissionUnionOrder =  1, Capital = "Dover",          Region = regions[6] };
    states[21] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NJ", Name = "New Jersey",     Area =   8722, AreaSqrKms =   22590, AdmissionUnionOrder =  3, Capital = "Trenton",        Region = regions[3] };
    states[22] = new CountriesStatistics07.Models.Federation() { Abbreviation = "AK", Name = "Alaska",         Area = 656424, AreaSqrKms = 1700139, AdmissionUnionOrder = 49, Capital = "Juneau",         Region = regions[5] };
    states[23] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NM", Name = "New Mexico",     Area = 121598, AreaSqrKms =  314939, AdmissionUnionOrder = 47, Capital = "Santa Fe",       Region = regions[4] };
    states[24] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NY", Name = "New York",       Area =  54475, AreaSqrKms =  141089, AdmissionUnionOrder = 11, Capital = "Albany",         Region = regions[3] };
    states[25] = new CountriesStatistics07.Models.Federation() { Abbreviation = "CA", Name = "California",     Area = 163707, AreaSqrKms =  424002, AdmissionUnionOrder = 31, Capital = "Sacramento",     Region = regions[5] };
    states[26] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MO", Name = "Missouri",       Area =  69709, AreaSqrKms =  180546, AdmissionUnionOrder = 24, Capital = "Jefferson City", Region = regions[7] };
    states[27] = new CountriesStatistics07.Models.Federation() { Abbreviation = "OK", Name = "Oklahoma",       Area =  69903, AreaSqrKms =  181049, AdmissionUnionOrder = 46, Capital = "Oklahoma City",  Region = regions[8] };
    states[28] = new CountriesStatistics07.Models.Federation() { Abbreviation = "PA", Name = "Pennsylvania",   Area =  46058, AreaSqrKms =  119291, AdmissionUnionOrder =  2, Capital = "Harrisburg",     Region = regions[3] };
    states[29] = new CountriesStatistics07.Models.Federation() { Abbreviation = "SC", Name = "South Carolina", Area =  32007, AreaSqrKms =   82898, AdmissionUnionOrder =  8, Capital = "Columbia",       Region = regions[6] };
    states[30] = new CountriesStatistics07.Models.Federation() { Abbreviation = "WY", Name = "Wyoming",        Area =  97818, AreaSqrKms =  253349, AdmissionUnionOrder = 44, Capital = "Cheyenne",       Region = regions[4] };
    states[31] = new CountriesStatistics07.Models.Federation() { Abbreviation = "SD", Name = "South Dakota",   Area =  77122, AreaSqrKms =  199745, AdmissionUnionOrder = 40, Capital = "Pierre",         Region = regions[7] };
    states[32] = new CountriesStatistics07.Models.Federation() { Abbreviation = "UT", Name = "Utah",           Area =  84904, AreaSqrKms =  219902, AdmissionUnionOrder = 45, Capital = "Salt Lake City", Region = regions[4] };
    states[33] = new CountriesStatistics07.Models.Federation() { Abbreviation = "AL", Name = "Alabama",        Area =  52423, AreaSqrKms =  135775, AdmissionUnionOrder = 22, Capital = "Montgomery",     Region = regions[1] };
    states[34] = new CountriesStatistics07.Models.Federation() { Abbreviation = "VT", Name = "Vermont",        Area =   9615, AreaSqrKms =   24903, AdmissionUnionOrder = 14, Capital = "Montpelier",     Region = regions[2] };
    states[35] = new CountriesStatistics07.Models.Federation() { Abbreviation = "AR", Name = "Arkansas",       Area =  53182, AreaSqrKms =  137742, AdmissionUnionOrder = 25, Capital = "Little Rock",    Region = regions[8] };
    states[36] = new CountriesStatistics07.Models.Federation() { Abbreviation = "WA", Name = "Washington",     Area =  71303, AreaSqrKms =  184674, AdmissionUnionOrder = 42, Capital = "Olympia",        Region = regions[5] };
    states[37] = new CountriesStatistics07.Models.Federation() { Abbreviation = "AZ", Name = "Arizona",        Area = 114006, AreaSqrKms =  295276, AdmissionUnionOrder = 48, Capital = "Phoenix",        Region = regions[4] };
    states[38] = new CountriesStatistics07.Models.Federation() { Abbreviation = "WV", Name = "West Virginia",  Area =  24231, AreaSqrKms =   62759, AdmissionUnionOrder = 35, Capital = "Charleston",     Region = regions[6] };
    states[39] = new CountriesStatistics07.Models.Federation() { Abbreviation = "LA", Name = "Louisiana",      Area =  51844, AreaSqrKms =  134275, AdmissionUnionOrder = 18, Capital = "Baton Rouge",    Region = regions[8] };

    if(IsPost)
    {
        Array.Sort(states);
    }
}

@using (Html.BeginForm())
{
    <p class="text-center"><input type="submit" name="btnSubmit" value="Sort by State Name" /></p>

    <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>
            <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>

        @while (counter <= states.Length - 1)
        {
            <tr>
                <td class="text-center">@(counter + 1)</td>
                <td class="text-center">@states[counter].Abbreviation</td>
                <td>@states[counter].StateName</td>
                <td class="text-right">@states[counter].AreaSqrMiles</td>
                <td class="text-right">@states[counter].AreaSqrKms</td>
                <td class="text-center">@states[counter].AdmissionUnionOrder</td>
                <td>@states[counter].Capital</td>
                <td>@states[counter].Region.Designation</td>
            </tr>

            counter++;
        }
    </table>
}
  43. In the Solution Explorer, under Views, expand Shared and double-click _Layout.cshtml
  44. 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")
</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("United States", "Index", "UnitedStates")</li>
                    <li>@Html.ActionLink("Germany", "About", "Home")</li>
                    <li>@Html.ActionLink("Australia", "About", "Home")</li>
                    <li>@Html.ActionLink("Mexico", "About", "Home")</li>
                    <li>@Html.ActionLink("About", "About", "Home")</li>
                    <li>@Html.ActionLink("Contact", "Contact", "Home")</li>
                </ul>
            </div>
        </div>
    </div>
    <div class="container body-content">
        @RenderBody()
        <hr />
        <footer>
            <p class="text-center">&copy; @DateTime.Now.Year - Countries Statistics</p>
        </footer>
    </div>

    @Scripts.Render("~/bundles/jquery")
    @Scripts.Render("~/bundles/bootstrap")
    @RenderSection("scripts", required: false)
</body>
</html>
  45. In the Solution Explorer, under Views and under UnitedStates, double-click Index.cshtml to access it
  46. To execute, on the main menu, click Debug -> Start Without Debugging:

    A Simple Form

  47. Click the Sort by State Name button:

    A Simple Form

  48. Close the browser and return to your programming environment

Reversing an Array

When you display the values of an array, they appear in the order they were added in the list. If you want, you can display the list from the last added item to the first added. To assist you with this operation, the Array class provides a method named Reverse. Its syntax is:

public static void Reverse(Array array);

This method neither arranges an array nor reverses a sorted array, It simply reverses whatever order the array holds. Here is an example of calling this method:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>
<h1>Numbers</h1>

@{
    double[] numbers = new double[8]
    {
        7628.937, 6.48, 574.9, 293749.064,
        0.70257, 314.905, 80458.01, 28.07
    };
}

<h3>Original List</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

@{  Array.Reverse(numbers); }

<h3>List in Reverse</h3>

<table>
@foreach (var number in numbers)
{
    <tr>
        <td>Number: @number</td>
    </tr>
}
</table>

</body>
</html>

This would produce:

A List in Reverse

In the same way, you can reverse

Resizing an Array

By definition, an array is is fixed list. This means that, when creating an array, you specify the number of its elements, then you starting adding values or objects to the array, but you cannot add items beyond the specified number. Sometimes in the real world, you may want to add items to array without having to recreate the array. To assist you with this operation, the Array class includes a static method named Resize.

The Array.Resize() method takes two arguments. The first argument is passed by reference and is the name of the array you want to resize. The second argument is a constant integer that is the new size of the array. If the new size is lower than the length of the original array, a new array is created with that new size. This means that, to increase the size of an array, you should pass the second argument as the size of the orginal array + the number of new items you want to add.

Practical LearningPractical Learning: Resizing an Array

  1. Change the code as follows: 
    . . . No Change


@{
    ViewBag.Title = "United States of America";
}

<h2 class="text-center">United States of America</h2>

@{
    int counter = 0;

    CountriesStatistics07.Models.Region[] regions = new CountriesStatistics07.Models.Region[]
    {
        . . . No Change
    };

    CountriesStatistics07.Models.Federation[] states = new CountriesStatistics07.Models.Federation[40];

    states[0]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "RI", StateName = "Rhode Island",   AreaSqrMiles =   1545, AreaSqrKms =    4002, AdmissionUnionOrder = 13, Capital = "Providence",     Region = regions[2] };

    . . . No Change

    states[39] = new CountriesStatistics07.Models.Federation() { Abbreviation = "LA", StateName = "Louisiana",      AreaSqrMiles =  51844, AreaSqrKms =  134275, AdmissionUnionOrder = 18, Capital = "Baton Rouge",    Region = regions[8] };

    Array.Resize(ref states, states.Length + 5);

    states[40] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MA", Name = "Massachusetts",  Area =  10555, AreaSqrKms =   27337, AdmissionUnionOrder =  6, Capital = "Boston",         Region = regions[2] };
    states[41] = new CountriesStatistics07.Models.Federation() { Abbreviation = "FL", Name = "Florida",        Area =  65758, AreaSqrKms =  170313, AdmissionUnionOrder = 27, Capital = "Tallahassee",    Region = regions[6] };
    states[42] = new CountriesStatistics07.Models.Federation() { Abbreviation = "GA", Name = "Georgia",        Area =  59441, AreaSqrKms =  153953, AdmissionUnionOrder =  4, Capital = "Atlanta",        Region = regions[6] };
    states[43] = new CountriesStatistics07.Models.Federation() { Abbreviation = "HI", Name = "Hawaii",         Area =  10932, AreaSqrKms =   28313, AdmissionUnionOrder = 50, Capital = "Honolulu",       Region = regions[5] };
    states[44] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MD", Name = "Maryland",       Area =  12407, AreaSqrKms =   32135, AdmissionUnionOrder =  7, Capital = "Annapolis",      Region = regions[6] };

    if (IsPost)
    {
        Array.Sort(states);
    }
}

@using (Html.BeginForm())
    {
    <p class="text-center"><input type="submit" name="btnSubmit" value="Sort by State Name" /></p>

    <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>
            <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>

        @while (counter <= states.Length - 1)
        {
            <tr>
                <td class="text-center">@(counter + 1)</td>
                <td class="text-center">@states[counter].Abbreviation</td>
                <td>@states[counter].StateName</td>
                <td class="text-right">@states[counter].AreaSqrMiles</td>
                <td class="text-right">@states[counter].AreaSqrKms</td>
                <td class="text-center">@states[counter].AdmissionUnionOrder</td>
                <td>@states[counter].Capital</td>
                <td>@states[counter].Region.Designation</td>
            </tr>

            counter++;
        }
    </table>
}
  2. To execute, on the main menu, click Debug -> Start Without Debugging:

    A Simple Form

  3. Click the Sort by State Name button:

    A Simple Form

  4. Close the browser and return to your programming environment

Copying an Array

Copying an array consists of assigning its values or objects to another array. To support this operation, the Array class provides various methods. The classic technique uses a method named Copy. It is overloaded in four versions for different scenarios. The easiest way to copy an array is through a version that takes three arguments. The first version takes three arguments: the source array, the destination array, and the number of items that will be copied.

Practical LearningPractical Learning: Copying an Array

  1. Change the code as follows: 
    @{
    ViewBag.Title = "United States of America";
}

<h2 class="text-center">United States of America</h2>

@{
    int counter = 0;

    CountriesStatistics07.Models.Region[] regions = new CountriesStatistics07.Models.Region[]
    {
        new CountriesStatistics07.Models.Region() { Designation = "East North Central", Description = "The East North Central region includes the states around the Great Lakes." },
        new CountriesStatistics07.Models.Region() { Designation = "East South Central", Description = "The East South Central portion is one of the regions designated as the South." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." },
        new CountriesStatistics07.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." }
    };

    CountriesStatistics07.Models.Federation[] states = new CountriesStatistics07.Models.Federation[40];

    states[0]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "RI", Name = "Rhode Island",   Area =   1545, AreaSqrKms =    4002, AdmissionUnionOrder = 13, Capital = "Providence",     Region = regions[2] };
    states[1]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "OH", Name = "Ohio",           Area =  44828, AreaSqrKms =  116103, AdmissionUnionOrder = 17, Capital = "Columbus",       Region = regions[0] };
    states[2]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "KY", Name = "Kentucky",       Area =  40411, AreaSqrKms =  104665, AdmissionUnionOrder = 15, Capital = "Frankfort",      Region = regions[2] };
    states[3]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "IA", Name = "Iowa",           Area =  56276, AreaSqrKms =  145754, AdmissionUnionOrder = 29, Capital = "Des Moines",     Region = regions[7] };
    states[4]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "WI", Name = "Wisconsin",      Area =  65503, AreaSqrKms =  169653, AdmissionUnionOrder = 30, Capital = "Madison",        Region = regions[0] };
    states[5]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "VT", Name = "Vermont",        Area =   9615, AreaSqrKms =   24903, AdmissionUnionOrder = 14, Capital = "Montpelier",     Region = regions[2] };
    states[6]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "ID", Name = "Idaho",          Area =  83574, AreaSqrKms =  216456, AdmissionUnionOrder = 43, Capital = "Boise",          Region = regions[4] };
    states[7]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "ME", Name = "Maine",          Area =  35387, AreaSqrKms =   91653, AdmissionUnionOrder = 23, Capital = "Augusta",        Region = regions[2] };
    states[8]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "OR", Name = "Oregon",         Area =  98386, AreaSqrKms =  254819, AdmissionUnionOrder = 33, Capital = "Salem",          Region = regions[5] };
    states[9]  = new CountriesStatistics07.Models.Federation() { Abbreviation = "ND", Name = "North Dakota",   Area =  70704, AreaSqrKms =  183123, AdmissionUnionOrder = 39, Capital = "Bismarck",       Region = regions[7] };
    states[10] = new CountriesStatistics07.Models.Federation() { Abbreviation = "IN", Name = "Indiana",        Area =  36420, AreaSqrKms =   94328, AdmissionUnionOrder = 19, Capital = "Indianapolis",   Region = regions[0] };
    states[11] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MS", Name = "Mississippi",    Area =  48434, AreaSqrKms =  125443, AdmissionUnionOrder = 20, Capital = "Jackson",        Region = regions[1] };
    states[12] = new CountriesStatistics07.Models.Federation() { Abbreviation = "TX", Name = "Texas",          Area = 268601, AreaSqrKms =  695676, AdmissionUnionOrder = 28, Capital = "Austin",         Region = regions[8] };
    states[13] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MT", Name = "Montana",        Area = 147046, AreaSqrKms =  380850, AdmissionUnionOrder = 41, Capital = "Helena",         Region = regions[4] };
    states[14] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NC", Name = "North Carolina", Area =  53821, AreaSqrKms =  139397, AdmissionUnionOrder = 12, Capital = "Raleigh",        Region = regions[6] };
    states[15] = new CountriesStatistics07.Models.Federation() { Abbreviation = "TN", Name = "Tennessee",      Area =  42146, AreaSqrKms =  109158, AdmissionUnionOrder = 16, Capital = "Nashville",      Region = regions[1] };
    states[16] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NE", Name = "Nebraska",       Area =  77358, AreaSqrKms =  200358, AdmissionUnionOrder = 37, Capital = "Lincoln",        Region = regions[7] };
    states[17] = new CountriesStatistics07.Models.Federation() { Abbreviation = "IL", Name = "Illinois",       Area =  57918, AreaSqrKms =  150007, AdmissionUnionOrder = 21, Capital = "Springfield",    Region = regions[0] };
    states[18] = new CountriesStatistics07.Models.Federation() { Abbreviation = "KS", Name = "Kansas",         Area =  82282, AreaSqrKms =  213110, AdmissionUnionOrder = 34, Capital = "Topeka",         Region = regions[7] };
    states[19] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NH", Name = "New Hampshire",  Area =   9351, AreaSqrKms =   24219, AdmissionUnionOrder =  9, Capital = "Concord",        Region = regions[2] };
    states[20] = new CountriesStatistics07.Models.Federation() { Abbreviation = "DE", Name = "Delaware",       Area =   2489, AreaSqrKms =    6447, AdmissionUnionOrder =  1, Capital = "Dover",          Region = regions[6] };
    states[21] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NJ", Name = "New Jersey",     Area =   8722, AreaSqrKms =   22590, AdmissionUnionOrder =  3, Capital = "Trenton",        Region = regions[3] };
    states[22] = new CountriesStatistics07.Models.Federation() { Abbreviation = "AK", Name = "Alaska",         Area = 656424, AreaSqrKms = 1700139, AdmissionUnionOrder = 49, Capital = "Juneau",         Region = regions[5] };
    states[23] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NM", Name = "New Mexico",     Area = 121598, AreaSqrKms =  314939, AdmissionUnionOrder = 47, Capital = "Santa Fe",       Region = regions[4] };
    states[24] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NY", Name = "New York",       Area =  54475, AreaSqrKms =  141089, AdmissionUnionOrder = 11, Capital = "Albany",         Region = regions[3] };
    states[25] = new CountriesStatistics07.Models.Federation() { Abbreviation = "CA", Name = "California",     Area = 163707, AreaSqrKms =  424002, AdmissionUnionOrder = 31, Capital = "Sacramento",     Region = regions[5] };
    states[26] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MO", Name = "Missouri",       Area =  69709, AreaSqrKms =  180546, AdmissionUnionOrder = 24, Capital = "Jefferson City", Region = regions[7] };
    states[27] = new CountriesStatistics07.Models.Federation() { Abbreviation = "OK", Name = "Oklahoma",       Area =  69903, AreaSqrKms =  181049, AdmissionUnionOrder = 46, Capital = "Oklahoma City",  Region = regions[8] };
    states[28] = new CountriesStatistics07.Models.Federation() { Abbreviation = "PA", Name = "Pennsylvania",   Area =  46058, AreaSqrKms =  119291, AdmissionUnionOrder =  2, Capital = "Harrisburg",     Region = regions[3] };
    states[29] = new CountriesStatistics07.Models.Federation() { Abbreviation = "SC", Name = "South Carolina", Area =  32007, AreaSqrKms =   82898, AdmissionUnionOrder =  8, Capital = "Columbia",       Region = regions[6] };
    states[30] = new CountriesStatistics07.Models.Federation() { Abbreviation = "WY", Name = "Wyoming",        Area =  97818, AreaSqrKms =  253349, AdmissionUnionOrder = 44, Capital = "Cheyenne",       Region = regions[4] };
    states[31] = new CountriesStatistics07.Models.Federation() { Abbreviation = "SD", Name = "South Dakota",   Area =  77122, AreaSqrKms =  199745, AdmissionUnionOrder = 40, Capital = "Pierre",         Region = regions[7] };
    states[32] = new CountriesStatistics07.Models.Federation() { Abbreviation = "UT", Name = "Utah",           Area =  84904, AreaSqrKms =  219902, AdmissionUnionOrder = 45, Capital = "Salt Lake City", Region = regions[4] };
    states[33] = new CountriesStatistics07.Models.Federation() { Abbreviation = "AL", Name = "Alabama",        Area =  52423, AreaSqrKms =  135775, AdmissionUnionOrder = 22, Capital = "Montgomery",     Region = regions[1] };
    states[34] = new CountriesStatistics07.Models.Federation() { Abbreviation = "VT", Name = "Vermont",        Area =   9615, AreaSqrKms =   24903, AdmissionUnionOrder = 14, Capital = "Montpelier",     Region = regions[2] };
    states[35] = new CountriesStatistics07.Models.Federation() { Abbreviation = "AR", Name = "Arkansas",       Area =  53182, AreaSqrKms =  137742, AdmissionUnionOrder = 25, Capital = "Little Rock",    Region = regions[8] };
    states[36] = new CountriesStatistics07.Models.Federation() { Abbreviation = "WA", Name = "Washington",     Area =  71303, AreaSqrKms =  184674, AdmissionUnionOrder = 42, Capital = "Olympia",        Region = regions[5] };
    states[37] = new CountriesStatistics07.Models.Federation() { Abbreviation = "AZ", Name = "Arizona",        Area = 114006, AreaSqrKms =  295276, AdmissionUnionOrder = 48, Capital = "Phoenix",        Region = regions[4] };
    states[38] = new CountriesStatistics07.Models.Federation() { Abbreviation = "WV", Name = "West Virginia",  Area =  24231, AreaSqrKms =   62759, AdmissionUnionOrder = 35, Capital = "Charleston",     Region = regions[6] };
    states[39] = new CountriesStatistics07.Models.Federation() { Abbreviation = "LA", Name = "Louisiana",      Area =  51844, AreaSqrKms =  134275, AdmissionUnionOrder = 18, Capital = "Baton Rouge",    Region = regions[8] };

    Array.Resize(ref states, states.Length + 5);

    states[40] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MA", Name = "Massachusetts",  Area =  10555, AreaSqrKms =   27337, AdmissionUnionOrder =  6, Capital = "Boston",         Region = regions[2] };
    states[41] = new CountriesStatistics07.Models.Federation() { Abbreviation = "FL", Name = "Florida",        Area =  65758, AreaSqrKms =  170313, AdmissionUnionOrder = 27, Capital = "Tallahassee",    Region = regions[6] };
    states[42] = new CountriesStatistics07.Models.Federation() { Abbreviation = "GA", Name = "Georgia",        Area =  59441, AreaSqrKms =  153953, AdmissionUnionOrder =  4, Capital = "Atlanta",        Region = regions[6] };
    states[43] = new CountriesStatistics07.Models.Federation() { Abbreviation = "HI", Name = "Hawaii",         Area =  10932, AreaSqrKms =   28313, AdmissionUnionOrder = 50, Capital = "Honolulu",       Region = regions[5] };
    states[44] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MD", Name = "Maryland",       Area =  12407, AreaSqrKms =   32135, AdmissionUnionOrder =  7, Capital = "Annapolis",      Region = regions[6] };

    CountriesStatistics07.Models.Federation[] temporary = new CountriesStatistics07.Models.Federation[states.Length + 5];
    Array.Copy(states, temporary, states.Length);
    states = temporary;

    states[45] = new CountriesStatistics07.Models.Federation() { Abbreviation = "CO", Name = "Colorado",       Area =  104100, AreaSqrKms = 269620, AdmissionUnionOrder = 38, Capital = "Denver",         Region = regions[4] };
    states[46] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MI", Name = "Michigan",       Area =   98810, AreaSqrKms = 250738, AdmissionUnionOrder = 26, Capital = "Lansing",        Region = regions[0] };
    states[47] = new CountriesStatistics07.Models.Federation() { Abbreviation = "MN", Name = "Minnesota",      Area =   86943, AreaSqrKms = 225182, AdmissionUnionOrder = 32, Capital = "Saint Paul",     Region = regions[7] };
    states[48] = new CountriesStatistics07.Models.Federation() { Abbreviation = "CT", Name = "Connecticut",    Area =    5544, AreaSqrKms =  14358, AdmissionUnionOrder =  5, Capital = "Hartford",       Region = regions[3] };
    states[49] = new CountriesStatistics07.Models.Federation() { Abbreviation = "NV", Name = "Nevada",         Area =  110567, AreaSqrKms = 286368, AdmissionUnionOrder = 36, Capital = "Frankfort",      Region = regions[4] };

    if (IsPost)
    {
        Array.Sort(states);
    }
}

@using (Html.BeginForm())
{
    <p class="text-center"><input type="submit" name="btnSubmit" value="Sort by State Name" /></p>

    <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>
            <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>

        @while (counter <= states.Length - 1)
        {
            <tr>
                <td class="text-center">@(counter + 1)</td>
                <td class="text-center">@states[counter].Abbreviation</td>
                <td>@states[counter].StateName</td>
                <td class="text-right">@states[counter].AreaSqrMiles</td>
                <td class="text-right">@states[counter].AreaSqrKms</td>
                <td class="text-center">@states[counter].AdmissionUnionOrder</td>
                <td>@states[counter].Capital</td>
                <td>@states[counter].Region.Designation</td>
            </tr>

            counter++;
        }
    </table>
}
  2. To execute, on the main menu, click Debug -> Start Without Debugging:

    A Simple Form

  3. Click the Sort by State Name button:

    A Simple Form

  4. Close the browser and return to your programming environment

Finding an Item in an Array

The Array class provides various means of looking for, or locating, an element in an array.

To support binary search, the Array class is equipped with a method named BinarySearch that is overloaded in 8 versions. One of the versions uses the following syntax:

public static int BinarySearch(Array array, object value);

Before calling this method, you can sort the array. Here is an example of calling it:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>
<h1>Numbers</h1>

@{
    int[] numbers = new[] { 102, 44, 525, 38, 6, 28, 24481, 327, 632, 104 };
}

<h3>List of Items</h3>

@{ Array.Sort(numbers); }

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

@{ int index = Array.BinarySearch(numbers, 525); }

<p>The index of 525 is @index</p>

</body>
</html>

This would produce:

Finding an Item in an Array

Locating the Index of an Element

One of the most routine operations you can perform on an array is to find out whether it contains this or that value. For example, if the array contains a certain member, you may want to retrieve the index of that member. To assist you with this, the Array class is equipped with a method named IndexOf() method that comes in various versions. To apply it on the type of array we have used so far, you can use the following syntax:

public static int IndexOf(Array array, object value);

This method visits each member of the array, looking for the value. Once it finds value in the array, it stops and returns the index where the first occurrence of value was found. If the Array.IndexOf() method finds the value in the array, it returns its position. Here is an example of calling it:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>
<h1>Numbers</h1>

@{
    double[] numbers = new[]
    {
        7628.937, 6.48, 574.9, 293749.064,
        0.70257, 314.905, 80458.01
    };
}

<h3>List of Items</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

@{ int index = Array.IndexOf(numbers, 314.905); }

<p>The index of 314.905 is @index</p>

</body>
</html>

This would produce:

Finding an Item in an Array

If the item is not found in the array, the method may return -1.

The IndexOf() method actually looks for the first occurrence of an item in an array. If you prefer to get the last occurrence of that item in the array, you can call the Array.LastIndexOf() method. It also is overloaded in three versions.

Deleting Items From an Array

Deleting an item array consists of removing it from the list. The Array class allows you to delete one element or a range of items from an array. To support these operations, the class is equipped with a static method named Clear. Its syntax is:

public static void Clear(Array array, int index, int length);

The first argument of this method is the name of the array on which the operation is performed. The second argument is the index of the item where the deletion will occur or start. If that second index exists in the array, the third argument specifies the number of items to remove. If an item is deleted, it receives a default value. For example, if it is a number, it gets a 0 value.

If you want to delete just one item, provide its index as the second argument and 1 as the third. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>
<h1>Numbers</h1>

@{
    double[] numbers = new[]
    {
            7628.937, 6.48, 574.9, 293749.064,
            0.70257, 314.905, 80458.01
    };
}

<h3>Original List of Items</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

@{ Array.Clear(numbers, 2, 1); }

<h3>Modified List of Items</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

</body>
</html>

This would produce:

Deleting Items From an Array

To delete a range of items, pass the starting index as the second argument and pass the length of the range (the number of items to delete from the starting range) as the second argument. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>
<h1>Numbers</h1>

@{
    double[] numbers = new[]
    {
            7628.937, 6.48, 574.9, 293749.064,
            0.70257, 314.905, 80458.01
    };
}

<h3>Original List of Items</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

@{ Array.Clear(numbers, 2, 3); }

<h3>Modified List of Items</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

</body>
</html>

This would produce:

Deleting Items From an Array

Clearing an array consists of deleting all of its elements and setting the count to 0. To do it, call the Array.Clear() method. Pass 0 as the second argument and the length of the array as the third argument. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>
<h1>Numbers</h1>

@{
    double[] numbers = new[]
    {
            7628.937, 6.48, 574.9, 293749.064,
            0.70257, 314.905, 80458.01
    };
}

<h3>Original List of Items</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

@{ Array.Clear(numbers, 0, numbers.Length); }

<h3>Modified List of Items</h3>

<table>
    @foreach (var number in numbers)
    {
        <tr>
            <td>Number: @number</td>
        </tr>
    }
</table>

</body>
</html>

This would produce:

Deleting Items From an Array

Multidimensional Arrays

Two-Dimensional Arrays

The Array class supports the creation of any of the types of arrays we saw in the previous lessons. In the previous lesson, we saw that a two-dimensional array was an array made of two lists:

@{
    var members = new string[List1Length, List2Length];
}

To create such an array using the Array class, you can use the following version of the Array.CreateInstance() method:

public static Array CreateInstance(Type elementType, int length1, int length2)

The first argument is the type of array you want to create. The second argument is the length of the first list. The third argument is the length of the second list. Here are examples of using it:

@{
    Array numbers = Array.CreateInstance(typeof(double), 6, 3);
    var names = Array.CreateInstance(typeof(string), 2, 4);
    dynamic distances = Array.CreateInstance(typeof(string), 5, 17);
}

To specify the values of a two-dimensional array, you can use the following version of the Array.SetValue() method:

public void SetValue(object value, int index1, int index2)

The first argument is the value you want to add. The second argument is the index of the list. The second argument is the index of the element that is being added. Here is an example:

@{
        var members = Array.CreateInstance(typeof(string), 2, 4);
        
        members.SetValue("Celeste", 0, 0);  // 1st List - 1st Element
        members.SetValue("Mathurin", 0, 1); // 1st List - 2nd Element
        members.SetValue("Alex", 0, 2);     // 1st List - 3rd Element
        members.SetValue("Germain",0, 3);   // 1st List - 4th Element
        
    	members.SetValue("Jeremy", 1, 0);   // 2nd List - 1st Element
        members.SetValue("Mathew", 1, 1);   // 1st List - 2nd Element
        members.SetValue("Anselme", 1, 2);  // 1st List - 3rd Element
        members.SetValue("Frederique", 1, 3);// 1st List - 4th Element
}

Just as mentioned for the one-dimensional array, you can use the square brackets to create the array but call the SetValue() method to specify the value of each element.

To access a member of a two-dimensional array created with the Array.SetValue() method, you use the following version of the Array.GetValue() method:

public object GetValue(int index1, int index2)

This method takes two arguments. The first argument is the index of the list where the desired member resides. The second argument is the index of the element itself. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Employees</title>
</head>
<body>
<h1>Employees</h1>

@{
    var members = Array.CreateInstance(typeof(string), 2, 4);

    members.SetValue("Celeste", 0, 0);  // 1st List - 1st Element
    members.SetValue("Mathurin", 0, 1); // 1st List - 2nd Element
    members.SetValue("Alex", 0, 2);     // 1st List - 3rd Element
    members.SetValue("Germain", 0, 3);   // 1st List - 4th Element

    members.SetValue("Jeremy", 1, 0);   // 2nd List - 1st Element
    members.SetValue("Mathew", 1, 1);   // 1st List - 2nd Element
    members.SetValue("Anselme", 1, 2);  // 1st List - 3rd Element
    members.SetValue("Frederique", 1, 3);// 1st List - 4th Element
}

<p>Member: @members.GetValue(0, 2)</p>

</body>
</html>

To access each member of the list, you can use two for loops. Use the first loop to access each list. Nest a second loop to it to access each member. To get the dimension of the main list, you can call the Array.GetLength() method and specify its argument as 0. For the internal loop, pass 1 as the argument to the Array.GetLength() method. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Members</title>
</head>
<body>
<h1>Members</h1>

@{
    var members = Array.CreateInstance(typeof(string), 2, 4);

    members.SetValue("Celeste", 0, 0);  // 1st List - 1st Element
    members.SetValue("Mathurin", 0, 1); // 1st List - 2nd Element
    members.SetValue("Alex", 0, 2);     // 1st List - 3rd Element
    members.SetValue("Germain", 0, 3);   // 1st List - 4th Element

    members.SetValue("Jeremy", 1, 0);   // 2nd List - 1st Element
    members.SetValue("Mathew", 1, 1);   // 1st List - 2nd Element
    members.SetValue("Anselme", 1, 2);  // 1st List - 3rd Element
    members.SetValue("Frederique", 1, 3);// 1st List - 4th Element
}

@for(int list = 0; list < members.GetLength(0); list++)
{
    for (int counter = 0; counter < members.GetLength(1); counter++)
    {
        <p>Member: @members.GetValue(list, counter)</p>
    }
}
</body>
</html>

This would produce:

Two-Dimensional Arrays

You can also use a foreach operator to access each member of the array. When using it, there is no need for a counter. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Members</title>
</head>
<body>
<h1>Members</h1>

@{
    var members = Array.CreateInstance(typeof(string), 2, 4);

    members.SetValue("Celeste", 0, 0);  // 1st List - 1st Element
    members.SetValue("Mathurin", 0, 1); // 1st List - 2nd Element
    members.SetValue("Alex", 0, 2);     // 1st List - 3rd Element
    members.SetValue("Germain", 0, 3);   // 1st List - 4th Element

    members.SetValue("Jeremy", 1, 0);   // 2nd List - 1st Element
    members.SetValue("Mathew", 1, 1);   // 1st List - 2nd Element
    members.SetValue("Anselme", 1, 2);  // 1st List - 3rd Element
    members.SetValue("Frederique", 1, 3);// 1st List - 4th Element
}

@foreach(var member in members)
{
    <p>Member: @member</p>
}
</body>
</html>

Three-Dimensional Arrays

Instead of two dimensions, you may want to create a three-dimensional arrays. A 3-D array is an array that, if created with the square brackets, would use two commas. Here is an example:

@{
    double[,,] Number;
}

To create such an array using the Array class, you can usethe following version of its CreateInstance() method:

public static Array CreateInstance(Type elementType,
								   int length1,
								   int length2,
	 							   int length3)

Here is an example:

@{
    var number = Array.CreateInstance(typeof(double), 2, 3, 5);
}

To specify the value of each member of the three-dimensional array, you can call the following version of the Array.SetValue() method:

public void SetValue(Object value,
					 int index1,
					 int index2,
					 int index3)

Here is an example:

@{
        var number = Array.CreateInstance(typeof(double), 2, 3, 5);

        number.SetValue(  12.44, 0, 0, 0);
        number.SetValue( 525.38, 0, 0, 1);
        number.SetValue(  -6.28, 0, 0, 2);
        number.SetValue(2448.32, 0, 0, 3);
        number.SetValue( 632.04, 0, 0, 4);
        number.SetValue(-378.05, 0, 1, 0);
        number.SetValue(  48.14, 0, 1, 1);
        number.SetValue( 634.18, 0, 1, 2);
        number.SetValue( 762.48, 0, 1, 3);
        number.SetValue(  83.02, 0, 1, 4);
        number.SetValue(  64.92, 0, 2, 0);
        number.SetValue(  -7.44, 0, 2, 1);
        number.SetValue(  86.74, 0, 2, 2);
        number.SetValue(-534.60, 0, 2, 3);
        number.SetValue( 386.73, 0, 2, 4);
        number.SetValue(  48.02, 1, 0, 0);
        number.SetValue( 120.44, 1, 0, 1);
        number.SetValue(  38.62, 1, 0, 2);
        number.SetValue( 526.82, 1, 0, 3);
        number.SetValue(1704.62, 1, 0, 4);
        number.SetValue(  56.85, 1, 1, 0);
        number.SetValue(105.48,  1, 1, 1);
        number.SetValue( 363.31, 1, 1, 2);
        number.SetValue( 172.62, 1, 1, 3);
        number.SetValue( 128.48, 1, 1, 4);
        number.SetValue( 906.68, 1, 2, 0);
        number.SetValue(  47.12, 1, 2, 1);
        number.SetValue(-166.07, 1, 2, 2);
        number.SetValue(4444.26, 1, 2, 3);
        number.SetValue( 408.62, 1, 2, 4);
}

To get the value of each member of the three-dimensional array, you can call the following version of the Array.GetValue() method:

public Object GetValue(int index1,
					   int index2,
					   int index3)

Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>

@{
    var number = Array.CreateInstance(typeof(double), 2, 3, 5);

    number.SetValue(12.44, 0, 0, 0);
    number.SetValue(525.38, 0, 0, 1);
    number.SetValue(-6.28, 0, 0, 2);
    number.SetValue(2448.32, 0, 0, 3);
    number.SetValue(632.04, 0, 0, 4);
    number.SetValue(-378.05, 0, 1, 0);
    number.SetValue(48.14, 0, 1, 1);
    number.SetValue(634.18, 0, 1, 2);
    number.SetValue(762.48, 0, 1, 3);
    number.SetValue(83.02, 0, 1, 4);
    number.SetValue(64.92, 0, 2, 0);
    number.SetValue(-7.44, 0, 2, 1);
    number.SetValue(86.74, 0, 2, 2);
    number.SetValue(-534.60, 0, 2, 3);
    number.SetValue(386.73, 0, 2, 4);
    number.SetValue(48.02, 1, 0, 0);
    number.SetValue(120.44, 1, 0, 1);
    number.SetValue(38.62, 1, 0, 2);
    number.SetValue(526.82, 1, 0, 3);
    number.SetValue(1704.62, 1, 0, 4);
    number.SetValue(56.85, 1, 1, 0);
    number.SetValue(105.48, 1, 1, 1);
    number.SetValue(363.31, 1, 1, 2);
    number.SetValue(172.62, 1, 1, 3);
    number.SetValue(128.48, 1, 1, 4);
    number.SetValue(906.68, 1, 2, 0);
    number.SetValue(47.12, 1, 2, 1);
    number.SetValue(-166.07, 1, 2, 2);
    number.SetValue(4444.26, 1, 2, 3);
    number.SetValue(408.62, 1, 2, 4);
}

<p>Number: @number.GetValue(0, 2, 4)</p>
</body>
</html>

This would produce:

Three-Dimensional Arrays

To access each member of the array, you can use three for loops. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>

@{
    var number = Array.CreateInstance(typeof(double), 2, 3, 5);

    number.SetValue(12.44, 0, 0, 0);
    number.SetValue(525.38, 0, 0, 1);
    number.SetValue(-6.28, 0, 0, 2);
    number.SetValue(2448.32, 0, 0, 3);
    number.SetValue(632.04, 0, 0, 4);
    number.SetValue(-378.05, 0, 1, 0);
    number.SetValue(48.14, 0, 1, 1);
    number.SetValue(634.18, 0, 1, 2);
    number.SetValue(762.48, 0, 1, 3);
    number.SetValue(83.02, 0, 1, 4);
    number.SetValue(64.92, 0, 2, 0);
    number.SetValue(-7.44, 0, 2, 1);
    number.SetValue(86.74, 0, 2, 2);
    number.SetValue(-534.60, 0, 2, 3);
    number.SetValue(386.73, 0, 2, 4);
    number.SetValue(48.02, 1, 0, 0);
    number.SetValue(120.44, 1, 0, 1);
    number.SetValue(38.62, 1, 0, 2);
    number.SetValue(526.82, 1, 0, 3);
    number.SetValue(1704.62, 1, 0, 4);
    number.SetValue(56.85, 1, 1, 0);
    number.SetValue(105.48, 1, 1, 1);
    number.SetValue(363.31, 1, 1, 2);
    number.SetValue(172.62, 1, 1, 3);
    number.SetValue(128.48, 1, 1, 4);
    number.SetValue(906.68, 1, 2, 0);
    number.SetValue(47.12, 1, 2, 1);
    number.SetValue(-166.07, 1, 2, 2);
    number.SetValue(4444.26, 1, 2, 3);
    number.SetValue(408.62, 1, 2, 4);
}

<table>
@for (int m = 0; m < number.GetLength(0); m++)
{
    for (int n = 0; n < number.GetLength(1); n++)
    {
        for (int element = 0; element < number.GetLength(2); element++)
        {
            <tr>
                <td>Number:</td>
                <td>@number.GetValue(m, n, element)</td>
            </tr>
        }
    }
}
</table>
</body>
</html>

This would produce:

Three-Dimensional Arrays

You can also use a foreach loop to access each member of the array. Here is an example:

<!DOCTYPE html>
<html>
<head>
<title>Numbers</title>
</head>
<body>

@{
    var numbers = Array.CreateInstance(typeof(double), 2, 3, 5);

    numbers.SetValue(12.44, 0, 0, 0);
    numbers.SetValue(525.38, 0, 0, 1);
    numbers.SetValue(-6.28, 0, 0, 2);
    numbers.SetValue(2448.32, 0, 0, 3);
    numbers.SetValue(632.04, 0, 0, 4);
    numbers.SetValue(-378.05, 0, 1, 0);
    numbers.SetValue(48.14, 0, 1, 1);
    numbers.SetValue(634.18, 0, 1, 2);
    numbers.SetValue(762.48, 0, 1, 3);
    numbers.SetValue(83.02, 0, 1, 4);
    numbers.SetValue(64.92, 0, 2, 0);
    numbers.SetValue(-7.44, 0, 2, 1);
    numbers.SetValue(86.74, 0, 2, 2);
    numbers.SetValue(-534.60, 0, 2, 3);
    numbers.SetValue(386.73, 0, 2, 4);
    numbers.SetValue(48.02, 1, 0, 0);
    numbers.SetValue(120.44, 1, 0, 1);
    numbers.SetValue(38.62, 1, 0, 2);
    numbers.SetValue(526.82, 1, 0, 3);
    numbers.SetValue(1704.62, 1, 0, 4);
    numbers.SetValue(56.85, 1, 1, 0);
    numbers.SetValue(105.48, 1, 1, 1);
    numbers.SetValue(363.31, 1, 1, 2);
    numbers.SetValue(172.62, 1, 1, 3);
    numbers.SetValue(128.48, 1, 1, 4);
    numbers.SetValue(906.68, 1, 2, 0);
    numbers.SetValue(47.12, 1, 2, 1);
    numbers.SetValue(-166.07, 1, 2, 2);
    numbers.SetValue(4444.26, 1, 2, 3);
    numbers.SetValue(408.62, 1, 2, 4);
}

<table>
@foreach(double number in numbers)
{
    <tr>
        <td>Number:</td>
        <td>@number</td>
    </tr>
}
</table>
</body>
</html>

Multidimensional Arrays

The Array class supports all dimensions of arrays beyond three. To create a multidimensional array, the class is equipped with the following version of its CreateInstance() method:

public static Array CreateInstance(Type elementType, params int[] lengths)

To add elements to the list, you can use the following equivalent version of the SetValue() method:

public void SetValue(object value, params int[] indices)

To get the value of an element, you would call the following version of the GetValue() method:

public Object GetValue(params int[] indices)

Getting Other Information About an Array

The Lower Bound of an Array

To better manage an array, the compiler must always be able to locate its highest and its lowest members. This is particularly important because an array must have a size.

The lowest member of an array can be located using the Array.GetLowerBound() method. Its syntax is:

public int GetLowerBound(int dimension);

The Upper Bound of an Array

The highest member of an array can be located using the Array.GetUpperBound() method. Its syntax is:

public int GetUpperBound(int dimension);

In both cases, the dimension argument is the rank of the array. For a single-dimensional array, as those we have always used so far, this parameter must have the value of 0.

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