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ArrayList.IndexOf Metodo

Definizione

Restituisce l'indice in base zero della prima occorrenza di un valore in ArrayList o in una parte di esso.

Overload

IndexOf(Object)

Cerca l'oggetto Object specificato e restituisce l'indice in base zero della prima occorrenza all'interno dell'intero ArrayList.

IndexOf(Object, Int32)

Cerca l'oggetto Object specificato e restituisce l'indice in base zero della prima occorrenza all'interno dell'intervallo di elementi dell'oggetto ArrayList compreso tra l'indice specificato e l'ultimo elemento.

IndexOf(Object, Int32, Int32)

Cerca l'oggetto Object specificato e restituisce l'indice in base zero della prima occorrenza all'interno dell'intervallo di elementi nell'oggetto ArrayList che inizia in corrispondenza dell'indice specificato e contiene il numero specificato di elementi.

IndexOf(Object)

Origine:
ArrayList.cs
Origine:
ArrayList.cs
Origine:
ArrayList.cs

Cerca l'oggetto Object specificato e restituisce l'indice in base zero della prima occorrenza all'interno dell'intero ArrayList.

public:
 virtual int IndexOf(System::Object ^ value);
public virtual int IndexOf (object value);
public virtual int IndexOf (object? value);
abstract member IndexOf : obj -> int
override this.IndexOf : obj -> int
Public Overridable Function IndexOf (value As Object) As Integer

Parametri

value
Object

Oggetto Object da individuare in ArrayList. Il valore può essere null.

Restituisce

Indice in base zero della prima occorrenza di value all'interno dell'intero oggetto ArrayList, se presente; in caso contrario, -1.

Implementazioni

Esempio

Nell'esempio di codice seguente viene illustrato come determinare l'indice della prima occorrenza di un elemento specificato.

using namespace System;
using namespace System::Collections;
void PrintIndexAndValues( IEnumerable^ myList );
int main()
{
   
   // Creates and initializes a new ArrayList with three elements of the same value.
   ArrayList^ myAL = gcnew ArrayList;
   myAL->Add( "the" );
   myAL->Add( "quick" );
   myAL->Add( "brown" );
   myAL->Add( "fox" );
   myAL->Add( "jumps" );
   myAL->Add( "over" );
   myAL->Add( "the" );
   myAL->Add( "lazy" );
   myAL->Add( "dog" );
   myAL->Add( "in" );
   myAL->Add( "the" );
   myAL->Add( "barn" );
   
   // Displays the values of the ArrayList.
   Console::WriteLine( "The ArrayList contains the following values:" );
   PrintIndexAndValues( myAL );
   
   // Search for the first occurrence of the duplicated value.
   String^ myString = "the";
   int myIndex = myAL->IndexOf( myString );
   Console::WriteLine( "The first occurrence of \"{0}\" is at index {1}.", myString, myIndex );
   
   // Search for the first occurrence of the duplicated value in the last section of the ArrayList.
   myIndex = myAL->IndexOf( myString, 4 );
   Console::WriteLine( "The first occurrence of \"{0}\" between index 4 and the end is at index {1}.", myString, myIndex );
   
   // Search for the first occurrence of the duplicated value in a section of the ArrayList.
   myIndex = myAL->IndexOf( myString, 6, 6 );
   Console::WriteLine( "The first occurrence of \"{0}\" between index 6 and index 11 is at index {1}.", myString, myIndex );
}

void PrintIndexAndValues( IEnumerable^ myList )
{
   int i = 0;
   IEnumerator^ myEnum = myList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::WriteLine( "   [{0}]:    {1}", i++, obj );
   }

   Console::WriteLine();
}

/* 
 This code produces the following output.
 
 The ArrayList 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 11 is at index 6.
 */
using System;
using System.Collections;
public class SamplesArrayList
{

    public static void Main()
    {

        // Creates and initializes a new ArrayList with three elements of the same value.
        ArrayList myAL = new ArrayList();
        myAL.Add( "the" );
        myAL.Add( "quick" );
        myAL.Add( "brown" );
        myAL.Add( "fox" );
        myAL.Add( "jumps" );
        myAL.Add( "over" );
        myAL.Add( "the" );
        myAL.Add( "lazy" );
        myAL.Add( "dog" );
        myAL.Add( "in" );
        myAL.Add( "the" );
        myAL.Add( "barn" );

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

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

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

        // Search for the first occurrence of the duplicated value in a section of the ArrayList.
        myIndex = myAL.IndexOf( myString, 6, 6 );
        Console.WriteLine( "The first occurrence of \"{0}\" between index 6 and index 11 is at index {1}.", myString, myIndex );

        // Search for the first occurrence of the duplicated value in a small section at the end of the ArrayList.
        myIndex = myAL.IndexOf( myString, 11 );
        Console.WriteLine( "The first occurrence of \"{0}\" between index 11 and the end is at index {1}.", myString, myIndex );
    }

    public static void PrintIndexAndValues(IEnumerable myList)
    {
        int i = 0;
        foreach (Object obj in myList)
            Console.WriteLine("   [{0}]:    {1}", i++, obj);
        Console.WriteLine();
    }
}
/*
This code produces output similar to the following:

The ArrayList 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 11 is at index 6.
The first occurrence of "the" between index 11 and the end is at index -1.
*/
Imports System.Collections

Public Class SamplesArrayList


    Public Shared Sub Main()

        ' Creates and initializes a new ArrayList with three elements of the same value.
        Dim myAL As New ArrayList()
        myAL.Add("the")
        myAL.Add("quick")
        myAL.Add("brown")
        myAL.Add("fox")
        myAL.Add("jumps")
        myAL.Add("over")
        myAL.Add("the")
        myAL.Add("lazy")
        myAL.Add("dog")
        myAL.Add("in")
        myAL.Add("the")
        myAL.Add("barn")

        ' Displays the values of the ArrayList.
        Console.WriteLine("The ArrayList contains the following values:")
        PrintIndexAndValues(myAL)

        ' Search for the first occurrence of the duplicated value.
        Dim myString As [String] = "the"
        Dim myIndex As Integer = myAL.IndexOf(myString)
        Console.WriteLine("The first occurrence of ""{0}"" is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in the last section of the ArrayList.
        myIndex = myAL.IndexOf(myString, 4)
        Console.WriteLine("The first occurrence of ""{0}"" between index 4 and the end is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in a section of the ArrayList.
        myIndex = myAL.IndexOf(myString, 6, 6)
        Console.WriteLine("The first occurrence of ""{0}"" between index 6 and index 11 is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in a small section at the end of the ArrayList.
        myIndex = myAL.IndexOf(myString, 11)
        Console.WriteLine("The first occurrence of ""{0}"" between index 11 and the end is at index {1}.", myString, myIndex)

    End Sub

    Public Shared Sub PrintIndexAndValues(ByVal myList As IEnumerable)
        Dim i As Integer
        Dim obj As [Object]
        For Each obj In myList
            Console.WriteLine("   [{0}]:    {1}", i, obj)
            i = i + 1
        Next obj
        Console.WriteLine()
    End Sub

End Class

' This code produces the following output.
'
' The ArrayList 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 11 is at index 6.
' The first occurrence of "the" between index 11 and the end is at index -1.
'

Commenti

L'oggetto ArrayList viene cercato in avanti a partire dal primo elemento e terminando all'ultimo elemento.

Questo metodo esegue una ricerca lineare; pertanto, questo metodo è un'operazione O(n) , dove n è Count.

Questo metodo determina l'uguaglianza chiamando Object.Equals.

A partire da .NET Framework 2.0, questo metodo usa i metodi item e CompareTo gli oggetti Equals della raccolta per determinare se esiste l'elemento. Nelle versioni precedenti di .NET Framework questa determinazione è stata effettuata usando i Equals metodi e CompareTo del item parametro sugli oggetti dell'insieme.

Vedi anche

Si applica a

IndexOf(Object, Int32)

Origine:
ArrayList.cs
Origine:
ArrayList.cs
Origine:
ArrayList.cs

Cerca l'oggetto Object specificato e restituisce l'indice in base zero della prima occorrenza all'interno dell'intervallo di elementi dell'oggetto ArrayList compreso tra l'indice specificato e l'ultimo elemento.

public:
 virtual int IndexOf(System::Object ^ value, int startIndex);
public virtual int IndexOf (object value, int startIndex);
public virtual int IndexOf (object? value, int startIndex);
abstract member IndexOf : obj * int -> int
override this.IndexOf : obj * int -> int
Public Overridable Function IndexOf (value As Object, startIndex As Integer) As Integer

Parametri

value
Object

Oggetto Object da individuare in ArrayList. Il valore può essere null.

startIndex
Int32

Indice iniziale in base zero della ricerca. 0 (zero) è valido in un elenco vuoto.

Restituisce

Indice in base zero della prima occorrenza di value all'interno dell'intervallo di elementi dell'oggetto ArrayList compreso tra startIndex e l'ultimo elemento, se presente; in caso contrario, -1.

Eccezioni

startIndex non è compreso nell'intervallo di indici validi per ArrayList.

Esempio

Nell'esempio di codice seguente viene illustrato come determinare l'indice della prima occorrenza di un elemento specificato.

using namespace System;
using namespace System::Collections;
void PrintIndexAndValues( IEnumerable^ myList );
int main()
{
   
   // Creates and initializes a new ArrayList with three elements of the same value.
   ArrayList^ myAL = gcnew ArrayList;
   myAL->Add( "the" );
   myAL->Add( "quick" );
   myAL->Add( "brown" );
   myAL->Add( "fox" );
   myAL->Add( "jumps" );
   myAL->Add( "over" );
   myAL->Add( "the" );
   myAL->Add( "lazy" );
   myAL->Add( "dog" );
   myAL->Add( "in" );
   myAL->Add( "the" );
   myAL->Add( "barn" );
   
   // Displays the values of the ArrayList.
   Console::WriteLine( "The ArrayList contains the following values:" );
   PrintIndexAndValues( myAL );
   
   // Search for the first occurrence of the duplicated value.
   String^ myString = "the";
   int myIndex = myAL->IndexOf( myString );
   Console::WriteLine( "The first occurrence of \"{0}\" is at index {1}.", myString, myIndex );
   
   // Search for the first occurrence of the duplicated value in the last section of the ArrayList.
   myIndex = myAL->IndexOf( myString, 4 );
   Console::WriteLine( "The first occurrence of \"{0}\" between index 4 and the end is at index {1}.", myString, myIndex );
   
   // Search for the first occurrence of the duplicated value in a section of the ArrayList.
   myIndex = myAL->IndexOf( myString, 6, 6 );
   Console::WriteLine( "The first occurrence of \"{0}\" between index 6 and index 11 is at index {1}.", myString, myIndex );
}

void PrintIndexAndValues( IEnumerable^ myList )
{
   int i = 0;
   IEnumerator^ myEnum = myList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::WriteLine( "   [{0}]:    {1}", i++, obj );
   }

   Console::WriteLine();
}

/* 
 This code produces the following output.
 
 The ArrayList 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 11 is at index 6.
 */
using System;
using System.Collections;
public class SamplesArrayList
{

    public static void Main()
    {

        // Creates and initializes a new ArrayList with three elements of the same value.
        ArrayList myAL = new ArrayList();
        myAL.Add( "the" );
        myAL.Add( "quick" );
        myAL.Add( "brown" );
        myAL.Add( "fox" );
        myAL.Add( "jumps" );
        myAL.Add( "over" );
        myAL.Add( "the" );
        myAL.Add( "lazy" );
        myAL.Add( "dog" );
        myAL.Add( "in" );
        myAL.Add( "the" );
        myAL.Add( "barn" );

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

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

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

        // Search for the first occurrence of the duplicated value in a section of the ArrayList.
        myIndex = myAL.IndexOf( myString, 6, 6 );
        Console.WriteLine( "The first occurrence of \"{0}\" between index 6 and index 11 is at index {1}.", myString, myIndex );

        // Search for the first occurrence of the duplicated value in a small section at the end of the ArrayList.
        myIndex = myAL.IndexOf( myString, 11 );
        Console.WriteLine( "The first occurrence of \"{0}\" between index 11 and the end is at index {1}.", myString, myIndex );
    }

    public static void PrintIndexAndValues(IEnumerable myList)
    {
        int i = 0;
        foreach (Object obj in myList)
            Console.WriteLine("   [{0}]:    {1}", i++, obj);
        Console.WriteLine();
    }
}
/*
This code produces output similar to the following:

The ArrayList 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 11 is at index 6.
The first occurrence of "the" between index 11 and the end is at index -1.
*/
Imports System.Collections

Public Class SamplesArrayList


    Public Shared Sub Main()

        ' Creates and initializes a new ArrayList with three elements of the same value.
        Dim myAL As New ArrayList()
        myAL.Add("the")
        myAL.Add("quick")
        myAL.Add("brown")
        myAL.Add("fox")
        myAL.Add("jumps")
        myAL.Add("over")
        myAL.Add("the")
        myAL.Add("lazy")
        myAL.Add("dog")
        myAL.Add("in")
        myAL.Add("the")
        myAL.Add("barn")

        ' Displays the values of the ArrayList.
        Console.WriteLine("The ArrayList contains the following values:")
        PrintIndexAndValues(myAL)

        ' Search for the first occurrence of the duplicated value.
        Dim myString As [String] = "the"
        Dim myIndex As Integer = myAL.IndexOf(myString)
        Console.WriteLine("The first occurrence of ""{0}"" is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in the last section of the ArrayList.
        myIndex = myAL.IndexOf(myString, 4)
        Console.WriteLine("The first occurrence of ""{0}"" between index 4 and the end is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in a section of the ArrayList.
        myIndex = myAL.IndexOf(myString, 6, 6)
        Console.WriteLine("The first occurrence of ""{0}"" between index 6 and index 11 is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in a small section at the end of the ArrayList.
        myIndex = myAL.IndexOf(myString, 11)
        Console.WriteLine("The first occurrence of ""{0}"" between index 11 and the end is at index {1}.", myString, myIndex)

    End Sub

    Public Shared Sub PrintIndexAndValues(ByVal myList As IEnumerable)
        Dim i As Integer
        Dim obj As [Object]
        For Each obj In myList
            Console.WriteLine("   [{0}]:    {1}", i, obj)
            i = i + 1
        Next obj
        Console.WriteLine()
    End Sub

End Class

' This code produces the following output.
'
' The ArrayList 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 11 is at index 6.
' The first occurrence of "the" between index 11 and the end is at index -1.
'

Commenti

L'oggetto ArrayList viene cercato in avanti a startIndex partire da e terminando all'ultimo elemento.

Questo metodo esegue una ricerca lineare; pertanto, questo metodo è un'operazione O(n) , dove n è il numero di elementi da startIndex alla fine di ArrayList.

Questo metodo determina l'uguaglianza chiamando Object.Equals.

A partire da .NET Framework 2.0, questo metodo usa i metodi item e CompareTo gli oggetti Equals della raccolta per determinare se esiste l'elemento. Nelle versioni precedenti di .NET Framework questa determinazione è stata effettuata usando i Equals metodi e CompareTo del item parametro sugli oggetti dell'insieme.

Vedi anche

Si applica a

IndexOf(Object, Int32, Int32)

Origine:
ArrayList.cs
Origine:
ArrayList.cs
Origine:
ArrayList.cs

Cerca l'oggetto Object specificato e restituisce l'indice in base zero della prima occorrenza all'interno dell'intervallo di elementi nell'oggetto ArrayList che inizia in corrispondenza dell'indice specificato e contiene il numero specificato di elementi.

public:
 virtual int IndexOf(System::Object ^ value, int startIndex, int count);
public virtual int IndexOf (object value, int startIndex, int count);
public virtual int IndexOf (object? value, int startIndex, int count);
abstract member IndexOf : obj * int * int -> int
override this.IndexOf : obj * int * int -> int
Public Overridable Function IndexOf (value As Object, startIndex As Integer, count As Integer) As Integer

Parametri

value
Object

Oggetto Object da individuare in ArrayList. Il valore può essere null.

startIndex
Int32

Indice iniziale in base zero della ricerca. 0 (zero) è valido in un elenco vuoto.

count
Int32

Numero di elementi nella sezione in cui eseguire la ricerca.

Restituisce

Indice in base zero della prima occorrenza di value all'interno dell'intervallo di elementi dell'oggetto ArrayList che inizia da startIndex e contiene il numero di elementi corrispondente a count, se presente; in caso contrario, -1.

Eccezioni

startIndex non è compreso nell'intervallo di indici validi per ArrayList.

-oppure-

count è minore di zero.

-oppure-

startIndex e count non specificano una sezione valida in ArrayList.

Esempio

Nell'esempio di codice seguente viene illustrato come determinare l'indice della prima occorrenza di un elemento specificato.

using namespace System;
using namespace System::Collections;
void PrintIndexAndValues( IEnumerable^ myList );
int main()
{
   
   // Creates and initializes a new ArrayList with three elements of the same value.
   ArrayList^ myAL = gcnew ArrayList;
   myAL->Add( "the" );
   myAL->Add( "quick" );
   myAL->Add( "brown" );
   myAL->Add( "fox" );
   myAL->Add( "jumps" );
   myAL->Add( "over" );
   myAL->Add( "the" );
   myAL->Add( "lazy" );
   myAL->Add( "dog" );
   myAL->Add( "in" );
   myAL->Add( "the" );
   myAL->Add( "barn" );
   
   // Displays the values of the ArrayList.
   Console::WriteLine( "The ArrayList contains the following values:" );
   PrintIndexAndValues( myAL );
   
   // Search for the first occurrence of the duplicated value.
   String^ myString = "the";
   int myIndex = myAL->IndexOf( myString );
   Console::WriteLine( "The first occurrence of \"{0}\" is at index {1}.", myString, myIndex );
   
   // Search for the first occurrence of the duplicated value in the last section of the ArrayList.
   myIndex = myAL->IndexOf( myString, 4 );
   Console::WriteLine( "The first occurrence of \"{0}\" between index 4 and the end is at index {1}.", myString, myIndex );
   
   // Search for the first occurrence of the duplicated value in a section of the ArrayList.
   myIndex = myAL->IndexOf( myString, 6, 6 );
   Console::WriteLine( "The first occurrence of \"{0}\" between index 6 and index 11 is at index {1}.", myString, myIndex );
}

void PrintIndexAndValues( IEnumerable^ myList )
{
   int i = 0;
   IEnumerator^ myEnum = myList->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      Console::WriteLine( "   [{0}]:    {1}", i++, obj );
   }

   Console::WriteLine();
}

/* 
 This code produces the following output.
 
 The ArrayList 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 11 is at index 6.
 */
using System;
using System.Collections;
public class SamplesArrayList
{

    public static void Main()
    {

        // Creates and initializes a new ArrayList with three elements of the same value.
        ArrayList myAL = new ArrayList();
        myAL.Add( "the" );
        myAL.Add( "quick" );
        myAL.Add( "brown" );
        myAL.Add( "fox" );
        myAL.Add( "jumps" );
        myAL.Add( "over" );
        myAL.Add( "the" );
        myAL.Add( "lazy" );
        myAL.Add( "dog" );
        myAL.Add( "in" );
        myAL.Add( "the" );
        myAL.Add( "barn" );

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

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

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

        // Search for the first occurrence of the duplicated value in a section of the ArrayList.
        myIndex = myAL.IndexOf( myString, 6, 6 );
        Console.WriteLine( "The first occurrence of \"{0}\" between index 6 and index 11 is at index {1}.", myString, myIndex );

        // Search for the first occurrence of the duplicated value in a small section at the end of the ArrayList.
        myIndex = myAL.IndexOf( myString, 11 );
        Console.WriteLine( "The first occurrence of \"{0}\" between index 11 and the end is at index {1}.", myString, myIndex );
    }

    public static void PrintIndexAndValues(IEnumerable myList)
    {
        int i = 0;
        foreach (Object obj in myList)
            Console.WriteLine("   [{0}]:    {1}", i++, obj);
        Console.WriteLine();
    }
}
/*
This code produces output similar to the following:

The ArrayList 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 11 is at index 6.
The first occurrence of "the" between index 11 and the end is at index -1.
*/
Imports System.Collections

Public Class SamplesArrayList


    Public Shared Sub Main()

        ' Creates and initializes a new ArrayList with three elements of the same value.
        Dim myAL As New ArrayList()
        myAL.Add("the")
        myAL.Add("quick")
        myAL.Add("brown")
        myAL.Add("fox")
        myAL.Add("jumps")
        myAL.Add("over")
        myAL.Add("the")
        myAL.Add("lazy")
        myAL.Add("dog")
        myAL.Add("in")
        myAL.Add("the")
        myAL.Add("barn")

        ' Displays the values of the ArrayList.
        Console.WriteLine("The ArrayList contains the following values:")
        PrintIndexAndValues(myAL)

        ' Search for the first occurrence of the duplicated value.
        Dim myString As [String] = "the"
        Dim myIndex As Integer = myAL.IndexOf(myString)
        Console.WriteLine("The first occurrence of ""{0}"" is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in the last section of the ArrayList.
        myIndex = myAL.IndexOf(myString, 4)
        Console.WriteLine("The first occurrence of ""{0}"" between index 4 and the end is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in a section of the ArrayList.
        myIndex = myAL.IndexOf(myString, 6, 6)
        Console.WriteLine("The first occurrence of ""{0}"" between index 6 and index 11 is at index {1}.", myString, myIndex)

        ' Search for the first occurrence of the duplicated value in a small section at the end of the ArrayList.
        myIndex = myAL.IndexOf(myString, 11)
        Console.WriteLine("The first occurrence of ""{0}"" between index 11 and the end is at index {1}.", myString, myIndex)

    End Sub

    Public Shared Sub PrintIndexAndValues(ByVal myList As IEnumerable)
        Dim i As Integer
        Dim obj As [Object]
        For Each obj In myList
            Console.WriteLine("   [{0}]:    {1}", i, obj)
            i = i + 1
        Next obj
        Console.WriteLine()
    End Sub

End Class

' This code produces the following output.
'
' The ArrayList 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 11 is at index 6.
' The first occurrence of "the" between index 11 and the end is at index -1.
'

Commenti

L'oggetto ArrayList viene cercato in avanti a partire da e terminando a startIndexstartIndex meno count 1, se count è maggiore di 0.

Questo metodo esegue una ricerca lineare; pertanto, questo metodo è un'operazione O(n) , dove n è count.

Questo metodo determina l'uguaglianza chiamando Object.Equals.

A partire da .NET Framework 2.0, questo metodo usa i metodi item e CompareTo gli oggetti Equals della raccolta per determinare se esiste l'elemento. Nelle versioni precedenti di .NET Framework questa determinazione è stata effettuata usando i Equals metodi e CompareTo del item parametro sugli oggetti dell'insieme.

Vedi anche

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