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Array.IndexOf Method (Array, Object)

.NET Framework 1.1

Searches for the specified object and returns the index of the first occurrence within the entire one-dimensional Array.

[Visual Basic]
Overloads Public Shared Function IndexOf( _
   ByVal array As Array, _
   ByVal value As Object _
) As Integer
[C#]
public static int IndexOf(
 Array array,
 object value
);
[C++]
public: static int IndexOf(
 Array* array,
 Object* value
);
[JScript]
public static function IndexOf(
   array : Array,
 value : Object
) : int;

Parameters

array
The one-dimensional Array to search.
value
The object to locate in array.

Return Value

The index of the first occurrence of value within the entire array, if found; otherwise, the lower bound of the array - 1.

Exceptions

Exception Type Condition
ArgumentNullException array is a null reference (Nothing in Visual Basic).
RankException array is multidimensional.

Remarks

The one-dimensional Array is searched forward starting at the first element and ending at the last element.

The elements are compared to the specified value using the Object.Equals method. If the element type is a nonintrinsic (user-defined) type, the Equals implementation of that type is used.

Since most arrays will have a lower bound of zero, this method would generally return -1 when value is not found. In the rare case that the lower bound of the array is equal to Int32.MinValue and value is not found, this method returns Int32.MaxValue, which is System.Int32.MinValue - 1.

Example

The following code example shows how to determine the index of the first occurrence of a specified element.

[Visual Basic] 
Imports System
Imports Microsoft.VisualBasic

Public Class SamplesArray    
    
    Public Shared Sub Main()
        
        ' Creates and initializes a new Array with three elements of
        ' the same value.
        Dim myArray As Array = Array.CreateInstance(GetType(String), 12)
        myArray.SetValue("the", 0)
        myArray.SetValue("quick", 1)
        myArray.SetValue("brown", 2)
        myArray.SetValue("fox", 3)
        myArray.SetValue("jumps", 4)
        myArray.SetValue("over", 5)
        myArray.SetValue("the", 6)
        myArray.SetValue("lazy", 7)
        myArray.SetValue("dog", 8)
        myArray.SetValue("in", 9)
        myArray.SetValue("the", 10)
        myArray.SetValue("barn", 11)
        
        ' Displays the values of the Array.
        Console.WriteLine("The Array contains the following values:")
        PrintIndexAndValues(myArray)
        
        ' Searches for the first occurrence of the duplicated value.
        Dim myString As String = "the"
        Dim myIndex As Integer = Array.IndexOf(myArray, myString)
        Console.WriteLine("The first occurrence of ""{0}"" is at index {1}.", _
           myString, myIndex)
        
        ' Searches for the first occurrence of the duplicated value in the last
        ' section of the Array.
        myIndex = Array.IndexOf(myArray, myString, 4)
        Console.WriteLine("The first occurrence of ""{0}"" between index 4 " _
           + "and the end is at index {1}.", myString, myIndex)
        
        ' Searches for the first occurrence of the duplicated value in a section
        ' of the Array.
        myIndex = Array.IndexOf(myArray, myString, 6, 5)
        Console.WriteLine("The first occurrence of ""{0}"" between index 6 " _
           + "and index 10 is at index {1}.", myString, myIndex)
    End Sub
    
    
    Public Shared Sub PrintIndexAndValues(myArray As Array)
        Dim i As Integer
        For i = myArray.GetLowerBound(0) To myArray.GetUpperBound(0)
            Console.WriteLine(ControlChars.Tab + "[{0}]:" + ControlChars.Tab _
               + "{1}", i, myArray.GetValue(i))
        Next i
    End Sub
End Class

' This code produces the following output.
' 
' The Array contains the following values:
'     [0]:    the
'     [1]:    quick
'     [2]:    brown
'     [3]:    fox
'     [4]:    jumps
'     [5]:    over
'     [6]:    the
'     [7]:    lazy
'     [8]:    dog
'     [9]:    in
'     [10]:    the
'     [11]:    barn
' The first occurrence of "the" is at index 0.
' The first occurrence of "the" between index 4 and the end is at index 6.
' The first occurrence of "the" between index 6 and index 10 is at index 6. 

[C#] 
using System;
public class SamplesArray  {

   public static void Main()  {

      // Creates and initializes a new Array with three elements of the same value.
      Array myArray=Array.CreateInstance( typeof(String), 12 );
      myArray.SetValue( "the", 0 );
      myArray.SetValue( "quick", 1 );
      myArray.SetValue( "brown", 2 );
      myArray.SetValue( "fox", 3 );
      myArray.SetValue( "jumps", 4 );
      myArray.SetValue( "over", 5 );
      myArray.SetValue( "the", 6 );
      myArray.SetValue( "lazy", 7 );
      myArray.SetValue( "dog", 8 );
      myArray.SetValue( "in", 9 );
      myArray.SetValue( "the", 10 );
      myArray.SetValue( "barn", 11 );

      // Displays the values of the Array.
      Console.WriteLine( "The Array contains the following values:" );
      PrintIndexAndValues( myArray );

      // Searches for the first occurrence of the duplicated value.
      String myString = "the";
      int myIndex = Array.IndexOf( myArray, myString );
      Console.WriteLine( "The first occurrence of \"{0}\" is at index {1}.", myString, myIndex );

      // Searches for the first occurrence of the duplicated value in the last section of the Array.
      myIndex = Array.IndexOf( myArray, myString, 4 );
      Console.WriteLine( "The first occurrence of \"{0}\" between index 4 and the end is at index {1}.", myString, myIndex );

      // Searches for the first occurrence of the duplicated value in a section of the Array.
      myIndex = Array.IndexOf( myArray, myString, 6, 5 );
      Console.WriteLine( "The first occurrence of \"{0}\" between index 6 and index 10 is at index {1}.", myString, myIndex );
   }


   public static void PrintIndexAndValues( Array myArray )  {
      for ( int i = myArray.GetLowerBound(0); i <= myArray.GetUpperBound(0); i++ )
         Console.WriteLine( "\t[{0}]:\t{1}", i, myArray.GetValue( i ) );
   }
}
/*
This code produces the following output.

The Array contains the following values:
    [0]:    the
    [1]:    quick
    [2]:    brown
    [3]:    fox
    [4]:    jumps
    [5]:    over
    [6]:    the
    [7]:    lazy
    [8]:    dog
    [9]:    in
    [10]:    the
    [11]:    barn
The first occurrence of "the" is at index 0.
The first occurrence of "the" between index 4 and the end is at index 6.
The first occurrence of "the" between index 6 and index 10 is at index 6.
*/

[C++] 
#using <mscorlib.dll>
using namespace System;

void PrintIndexAndValues( Array* myArray );

void main()  {
 
    // Creates and initializes a new Array instance with three elements of the same value.
    Array* myArray = Array::CreateInstance( __typeof(String), 12 );
    myArray->SetValue( S"the", 0 );
    myArray->SetValue( S"quick", 1 );
    myArray->SetValue( S"brown", 2 );
    myArray->SetValue( S"fox", 3 );
    myArray->SetValue( S"jumped", 4 );
    myArray->SetValue( S"over", 5 );
    myArray->SetValue( S"the", 6 );
    myArray->SetValue( S"lazy", 7 );
    myArray->SetValue( S"dog", 8 );
    myArray->SetValue( S"in", 9 );
    myArray->SetValue( S"the", 10 );
    myArray->SetValue( S"barn", 11 );
 
    // Displays the values of the Array.
    Console::WriteLine( "The Array instance contains the following values:" );
    PrintIndexAndValues( myArray );
 
    // Searches for the first occurrence of the duplicated value.
    String* myString = "the";
    int myIndex = Array::IndexOf( myArray, myString );
    Console::WriteLine( "The first occurrence of \"{0}\" is at index {1}.", myString, __box(myIndex) );
 
    // Searches for the first occurrence of the duplicated value in the last section of the Array.
    myIndex = Array::IndexOf( myArray, myString, 4 );
    Console::WriteLine( "The first occurrence of \"{0}\" between index 4 and the end is at index {1}.", myString, __box(myIndex));
 
    // Searches for the first occurrence of the duplicated value in a section of the Array.
    myIndex = Array::IndexOf( myArray, myString, 6, 5 );
    Console::WriteLine( "The first occurrence of \"{0}\" between index 6 and index 10 is at index {1}.", myString, __box(myIndex));
}
 
 
void PrintIndexAndValues( Array* myArray )  {
    for ( int i = myArray->GetLowerBound(0); i <= myArray->GetUpperBound(0); i++ )
        Console::WriteLine( "\t[{0}]:\t{1}", __box(i), myArray->GetValue( i ) );
}

 /*
 This code produces the following output.
 
 The Array instance contains the following values:
     [0]:    the
     [1]:    quick
     [2]:    brown
     [3]:    fox
     [4]:    jumped
     [5]:    over
     [6]:    the
     [7]:    lazy
     [8]:    dog
     [9]:    in
     [10]:    the
     [11]:    barn
 The first occurrence of "the" is at index 0.
 The first occurrence of "the" between index 4 and the end is at index 6.
 The first occurrence of "the" between index 6 and index 10 is at index 6.
 */

[JScript] 
import System;

// Creates and initializes a new Array with three elements of the same value.
var myArray : System.Array = System.Array.CreateInstance( System.String, 12 );
myArray.SetValue( "the", 0 );
myArray.SetValue( "quick", 1 );
myArray.SetValue( "brown", 2 );
myArray.SetValue( "fox", 3 );
myArray.SetValue( "jumped", 4 );
myArray.SetValue( "over", 5 );
myArray.SetValue( "the", 6 );
myArray.SetValue( "lazy", 7 );
myArray.SetValue( "dog", 8 );
myArray.SetValue( "in", 9 );
myArray.SetValue( "the", 10 );
myArray.SetValue( "barn", 11 );

// Displays the values of the Array.
Console.WriteLine( "The Array contains the following values:" );
PrintIndexAndValues( myArray );

// Searches for the first occurrence of the duplicated value.
var myString : String = "the";
var myIndex : int = System.Array.IndexOf( myArray, myString );
Console.WriteLine( "The first occurrence of \"{0}\" is at index {1}.", myString, myIndex );

// Searches for the first occurrence of the duplicated value in the last section of the Array.
myIndex = System.Array.IndexOf( myArray, myString, 4 );
Console.WriteLine( "The first occurrence of \"{0}\" between index 4 and the end is at index {1}.", myString, myIndex );

// Searches for the first occurrence of the duplicated value in a section of the Array.
myIndex = System.Array.IndexOf( myArray, myString, 6, 5 );
Console.WriteLine( "The first occurrence of \"{0}\" between index 6 and index 10 is at index {1}.", myString, myIndex );
 
 
function PrintIndexAndValues( myArray : System.Array  )  {
   for ( var i : int = myArray.GetLowerBound(0); i <= myArray.GetUpperBound(0); i++ )
      Console.WriteLine( "\t[{0}]:\t{1}", i, myArray.GetValue( i ) );
}
 
 /*
 This code produces the following output.
 
 The Array contains the following values:
     [0]:    the
     [1]:    quick
     [2]:    brown
     [3]:    fox
     [4]:    jumped
     [5]:    over
     [6]:    the
     [7]:    lazy
     [8]:    dog
     [9]:    in
     [10]:    the
     [11]:    barn
 The first occurrence of "the" is at index 0.
 The first occurrence of "the" between index 4 and the end is at index 6.
 The first occurrence of "the" between index 6 and index 10 is at index 6.
 */

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, Common Language Infrastructure (CLI) Standard

See Also

Array Class | Array Members | System Namespace | Array.IndexOf Overload List | LastIndexOf | Performing Culture-Insensitive String Operations in Arrays

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