ASP.NET Tutorial/Collections/Array

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Array binding

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="SimpleArrayDataBinding" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">

   <title>Simple Data Binding to Array</title>

</head> <body>

   <form id="form1" runat="server">

Simple Data Binding to Array

     This example illustrates simple data binding. The drop-down list is data bound to an array.
     <asp:DropDownList ID="drpSample" runat="server" />
     
   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class SimpleArrayDataBinding : System.Web.UI.Page {

   protected void Page_Load(object sender, EventArgs e)
   {
      string[] names;
      names = new string[3] { "Austen", "Dante", "Goethe" };
      drpSample.DataSource = names;
      drpSample.DataBind();
   }

}</source>


Array with custom objects

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="UsingArrays" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Using Arrays</title>

</head> <body>

   <form id="form1" runat="server">

Using Objects in an Array

     This example illustrates how an array can contain multiple objects.
     <asp:Label ID="labMsg" runat="server" />
     
   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public abstract class AbstractEntity {

  private string _id;
 public AbstractEntity(string id)
 {
     _id = id;
 }
  public string Id
  {
     get { return _id; }
     set { _id = value; }
  }
  public abstract bool IsValid
  {
     get;
  }

} public class Customer: AbstractEntity {

  private string _firstName;
  private string _lastName;
  private string _phone;
  public Customer(string id, string firstName, string lastName, string phone): base(id)
  {
     _firstName = firstName;
     _lastName = lastName;
     _phone = phone;
  }
  public string FirstName
  {
     get { return _firstName; }
     set { _firstName = value; }
  }
  public string LastName
  {
     get { return _lastName; }
     set { _lastName = value; }
  }
  public string Phone
  {
     get { return _phone; }
     set { _phone = value; }
  }
  public string Name
  {
     get { return LastName + ", " + FirstName; }
  }
  public override bool IsValid
  {
     get
     {
        if (Id.Length > 0 && LastName.Length > 0)
           return true;
        else
           return false;
     }
  }
  public override string ToString()
  {
     return Id + "," + Name + "," + Phone; 
  }

} public partial class UsingArrays : System.Web.UI.Page {

   protected void Page_Load(object sender, EventArgs e)
   {
     Customer[] myCustomers = new Customer[] {
        new Customer("1", "A", "AA", "123-4567"),
        new Customer("2", "B", "BB", "456-1267"),
        new Customer("3", "C", "CC", "564-7823"),
        new Customer("4", "D", "DD", "253-6383")
     };
     Customer c1 = myCustomers[2];
     labMsg.Text = c1.FirstName + "
"; labMsg.Text += myCustomers.GetUpperBound(0) + "," + myCustomers.Length ;
labMsg.Text += "

Iteration Output

";
      IEnumerator ie = myCustomers.GetEnumerator();
      while (ie.MoveNext())
      {
         Customer c = (Customer)ie.Current;
         labMsg.Text += c.FirstName + "
"; } }

}</source>


Define and use array in asp.net page (C#)

   <source lang="csharp">

<%@ Page Language="C#" %> <script runat="server">

  string[] arrColors = new string[5];
  
  void Page_Load(Object Sender, EventArgs e) {
     arrColors[0] = "green";
     arrColors[1] = "red";
     arrColors[2] = "yellow";
     arrColors[3] = "blue";
     arrColors[4] = "violet";
     
     Response.Write("The first element is: ");
     Response.Write(arrColors[0] + "");
     
     Response.Write("The third element is: ");
     Response.Write(arrColors[2] + "");
     
     Response.Write("The 5-3 element is: ");
     Response.Write(arrColors[5-3] + "");
  }

</script> <html><body> </body></html></source>


Define and use array in asp.net page (VB)

   <source lang="csharp">

<%@ Page Language="VB" %> <script runat="server">

  dim arrColors(5) as String
  
  sub Page_Load(Sender as object, e as eventargs)
     arrColors(0) = "green"
     arrColors(1) = "red"
     arrColors(2) = "yellow"
     arrColors(3) = "blue"
     arrColors(4) = "violet"
     
     Response.Write("The first element is: ")
     Response.Write(arrColors(0) & "")
     
     Response.Write("The third element is: ")
     Response.Write(arrColors(2) & "")
     
     Response.Write("The 5-3 element is: ")
     Response.Write(arrColors(5-3) & "")
  end sub      

</script> <html><body> </body></html></source>


Looking for an object in an array by reference (C#)

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">
   </form>

</body> </html> File: Default.aspx.cs

using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class _Default : System.Web.UI.Page {

   protected void Page_Load(object sender, EventArgs e)
   {
       Person scott = new Person("A", "B");
       Person bill = new Person("C", "D");
       Person srini = new Person("E", "F");
       Person[] people = { bill, scott, srini };
       int indexOfC = Array.IndexOf(people, bill);
       Response.Write("C is at " + indexOfC + "
"); int indexOfA = Array.IndexOf(people, scott); Response.Write("A is at " + indexOfA + "
"); }

} public class Person {

   string FirstName;
   string LastName;
   public Person(string first, string last)
   {
       FirstName = first;
       LastName = last;
   }
   public string FullName
   {
       get
       {
           return FirstName + " " + LastName;
       }
   }

}</source>


Looking for an object in an array by reference (VB)

   <source lang="csharp">

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">
   </form>

</body> </html> File: Default.aspx.vb Imports Microsoft.VisualBasic Partial Class _Default

   Inherits System.Web.UI.Page
   Protected Sub Page_Load(ByVal sender As Object, _
           ByVal e As System.EventArgs) Handles Me.Load
       Dim scott As New Person("A", "B")
       Dim bill As New Person("C", "D")
       Dim srini As New Person("E", "F")
       Dim people() As Person = {bill, scott, srini}
       Dim indexOfC As Integer = Array.IndexOf(people, bill)
       Response.Write("C is at " & indexOfC & "
") Dim indexOfA As Integer = Array.IndexOf(people, scott) Response.Write("A is at " & indexOfA & "
") End Sub

End Class

Public Class Person

   Dim FirstName As String
   Dim LastName As String
   Public Sub New(ByVal First As String, ByVal Last As String)
       FirstName = First
       LastName = Last
   End Sub
   Public ReadOnly Property FullName() As String
       Get
           Return FirstName & " " & LastName
       End Get
   End Property

End Class</source>


Searching for an equivalent object with Array.BinarySearch (C#)

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">
   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class _Default : System.Web.UI.Page {

   protected void Page_Load(object sender, EventArgs e)
   {
       Person scott = new Person("A", "B");
       Person bill = new Person("C", "D");
       Person srini = new Person("E", "F");
       Person[] people = { bill, scott, srini };
       int indexOfC = Array.IndexOf(people, bill);
       Response.Write("C is at " + indexOfC + "
"); int indexOfA = Array.IndexOf(people, scott); Response.Write("A is at " + indexOfA + "
"); Person scott2 = new Person("A", "B"); int indexOfA2 = Array.IndexOf(people, scott2); Response.Write("A #2 is at " + indexOfA2 + "
"); int indexOfEquivalentA = Array.BinarySearch(people, scott2); Response.Write("An Equivalent A is at " + indexOfEquivalentA + "
"); }

} public class Person : IComparable {

   string FirstName;
   string LastName;
   public Person(string first, string last)
   {
       FirstName = first;
       LastName = last;
   }
   public string FullName
   {
       get
       {
           return FirstName + " " + LastName;
       }
   }
   int IComparable.rupareTo(object obj)
   {
       Person p2 = obj as Person;
       if (p2 == null) throw new ArgumentException("Object is not a Person!");
       int lastNameResult = this.LastName.rupareTo(p2.LastName);
       if (lastNameResult == 0)
       {
           int firstNameResult = this.FirstName.rupareTo(p2.FirstName);
           return firstNameResult;
       }
       else
       {
           return lastNameResult;
       }
   }

}</source>


Searching for an equivalent object with Array.BinarySearch (VB)

   <source lang="csharp">

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">
   </form>

</body> </html> File: Default.aspx.vb Imports Microsoft.VisualBasic Public Class Person

   Implements IComparable
   Dim FirstName As String
   Dim LastName As String
   Public Sub New(ByVal First As String, ByVal Last As String)
       FirstName = First
       LastName = Last
   End Sub
   Public ReadOnly Property FullName() As String
       Get
           Return FirstName & " " & LastName
       End Get
   End Property
   Public Function CompareTo(ByVal obj As Object) _
       As Integer Implements IComparable.rupareTo
       If Not TypeOf (obj) Is Person Then
           Throw New ArgumentException("Object is not a Person!")
       End If
       Dim p2 As Person = CType(obj, Person)
       Dim lastNameResult As Integer = Me.LastName.rupareTo(p2.LastName)
       If lastNameResult = 0 Then
           Dim firstNameResult As Integer = Me.FirstName.rupareTo(p2.FirstName)
           Return firstNameResult
       Else
           Return lastNameResult
       End If
   End Function

End Class Partial Class _Default

   Inherits System.Web.UI.Page
   Protected Sub Page_Load(ByVal sender As Object, _
           ByVal e As System.EventArgs) Handles Me.Load
       Dim scott As New Person("A", "B")
       Dim bill As New Person("C", "D")
       Dim srini As New Person("E", "F")
       Dim people() As Person = {bill, scott, srini}
       Dim indexOfC As Integer = Array.IndexOf(people, bill)
       Response.Write("C is at " & indexOfC & "
") Dim indexOfA As Integer = Array.IndexOf(people, scott) Response.Write("A is at " & indexOfA & "
") Dim scott2 As New Person("A", "B") Dim indexOfA2 As Integer = Array.IndexOf(people, scott2) Response.Write("A #2 is at " & indexOfA2 & "
") Dim indexOfEquivalentA As Integer = Array.BinarySearch(people, scott2) Response.Write("An Equivalent A is at " & indexOfEquivalentA & "
") End Sub

End Class</source>


Searching for a object in an array by reference (C#)

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">
   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class _Default : System.Web.UI.Page {

   protected void Page_Load(object sender, EventArgs e)
   {
       Person scott = new Person("A", "B");
       Person bill = new Person("C", "D");
       Person srini = new Person("E", "F");
       Person[] people = { bill, scott, srini };
       int indexOfC = Array.IndexOf(people, bill);
       Response.Write("C is at " + indexOfC + "
"); int indexOfA = Array.IndexOf(people, scott); Response.Write("A is at " + indexOfA + "
"); Person scott2 = new Person("A", "B"); int indexOfA2 = Array.IndexOf(people, scott2); Response.Write("A #2 is at " + indexOfA2 + "
"); }

} public class Person {

   string FirstName;
   string LastName;
   public Person(string first, string last)
   {
       FirstName = first;
       LastName = last;
   }
   public string FullName
   {
       get
       {
           return FirstName + " " + LastName;
       }
   }

}</source>


Searching for a object in an array by reference (VB)

   <source lang="csharp">

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">
   </form>

</body> </html> File: Default.aspx.vb Imports Microsoft.VisualBasic Public Class Person

   Dim FirstName As String
   Dim LastName As String
   Public Sub New(ByVal First As String, ByVal Last As String)
       FirstName = First
       LastName = Last
   End Sub
   Public ReadOnly Property FullName() As String
       Get
           Return FirstName & " " & LastName
       End Get
   End Property

End Class Partial Class _Default

   Inherits System.Web.UI.Page
   Protected Sub Page_Load(ByVal sender As Object, _
           ByVal e As System.EventArgs) Handles Me.Load
       Dim scott As New Person("A", "B")
       Dim bill As New Person("C", "D")
       Dim srini As New Person("E", "F")
       Dim people() As Person = {bill, scott, srini}
       Dim indexOfC As Integer = Array.IndexOf(people, bill)
       Response.Write("C is at " & indexOfC & "
") Dim indexOfA As Integer = Array.IndexOf(people, scott) Response.Write("A is at " & indexOfA & "
") Dim scott2 As New Person("A", "B") Dim indexOfA2 As Integer = Array.IndexOf(people, scott2) Response.Write("A #2 is at " & indexOfA2 & "
") End Sub

End Class</source>


Sorting arrays of Person (C#)

   <source lang="csharp">

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">
   </form>

</body> </html> File: Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class _Default : System.Web.UI.Page {

   protected void Page_Load(object sender, EventArgs e)
   {
       Person scott = new Person("A", "B");
       Person bill = new Person("C", "D");
       Person srini = new Person("E", "F");
       Person[] people = { scott, bill, srini };
       Response.Write("Unsorted. We used foreach.
"); foreach (Person p in people) { Response.Write(p.FullName + "
"); } Response.Write("Sort...
"); Array.Sort(people); Response.Write("Sorted. We used foreach.
"); foreach (Person p in people) { Response.Write(p.FullName + "
"); } }

}

public class Person : IComparable {

   string FirstName;
   string LastName;
   public Person(string first, string last)
   {
       FirstName = first;
       LastName = last;
   }
   public string FullName
   {
       get
       {
           return FirstName + " " + LastName;
       }
   }
   int IComparable.rupareTo(object obj)
   {
       Person p2 = obj as Person;
       if (p2 == null) throw new ArgumentException("Object is not a Person!");
       int lastNameResult = this.LastName.rupareTo(p2.LastName);
       if (lastNameResult == 0)
       {
           int firstNameResult = this.FirstName.rupareTo(p2.FirstName);
           return firstNameResult;
       }
       else
       {
           return lastNameResult;
       }
   }

}</source>


Sorting arrays of Person (VB)

   <source lang="csharp">

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server">

   <title>Untitled Page</title>

</head> <body>

   <form id="form1" runat="server">
   </form>

</body> </html> File: Default.aspx.vb Imports Microsoft.VisualBasic Public Class Person

   Implements IComparable
   Dim FirstName As String
   Dim LastName As String
   Public Sub New(ByVal First As String, ByVal Last As String)
       FirstName = First
       LastName = Last
   End Sub
   Public ReadOnly Property FullName() As String
       Get
           Return FirstName & " " & LastName
       End Get
   End Property
   Public Function CompareTo(ByVal obj As Object) _
       As Integer Implements IComparable.rupareTo
       If Not TypeOf (obj) Is Person Then
           Throw New ArgumentException("Object is not a Person!")
       End If
       Dim p2 As Person = CType(obj, Person)
       Dim lastNameResult As Integer = Me.LastName.rupareTo(p2.LastName)
       If lastNameResult = 0 Then
           Dim firstNameResult As Integer = Me.FirstName.rupareTo(p2.FirstName)
           Return firstNameResult
       Else
           Return lastNameResult
       End If
   End Function

End Class Partial Class _Default

   Inherits System.Web.UI.Page
   Protected Sub Page_Load(ByVal sender As Object, _
           ByVal e As System.EventArgs) Handles Me.Load
       Dim scott As New Person("A", "B")
       Dim bill As New Person("C", "D")
       Dim srini As New Person("E", "F")
       Dim people() As Person = {scott, bill, srini}
       Response.Write("Unsorted. We used foreach.
") For Each p As Person In people Response.Write(p.FullName & "
") Next Response.Write("Sort...
") Array.Sort(people) Response.Write("Sorted. We used foreach.
") For Each p As Person In people Response.Write(p.FullName & "
") Next End Sub

End Class</source>