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StringCollection.IndexOf Method

Searches for the specified string and returns the zero-based index of the first occurrence within the StringCollection.

Namespace: System.Collections.Specialized
Assembly: System (in system.dll)

public int IndexOf (
	string value
)
public int IndexOf (
	String value
)
public function IndexOf (
	value : String
) : int
Not applicable.

Parameters

value

The string to locate. The value can be a null reference (Nothing in Visual Basic).

Return Value

The zero-based index of the first occurrence of value in the StringCollection, if found; otherwise, -1.

This method determines equality by calling Object.Equals. String comparisons are case-sensitive.

This method performs a linear search; therefore, this method is an O(n) operation, where n is Count.

Starting with the .NET Framework 2.0, this method uses the collection’s objects’ Equals and CompareTo methods on item to determine whether item exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the item parameter on the objects in the collection.

The following code example searches the StringCollection for an element.

using System;
using System.Collections;
using System.Collections.Specialized;

public class SamplesStringCollection  {

   public static void Main()  {

      // Creates and initializes a new StringCollection.
      StringCollection myCol = new StringCollection();
      String[] myArr = new String[] { "RED", "orange", "yellow", "RED", "green", "blue", "RED", "indigo", "violet", "RED" };
      myCol.AddRange( myArr );

      Console.WriteLine( "Initial contents of the StringCollection:" );
      PrintValues( myCol );

      // Checks whether the collection contains "orange" and, if so, displays its index.
      if ( myCol.Contains( "orange" ) )
         Console.WriteLine( "The collection contains \"orange\" at index {0}.", myCol.IndexOf( "orange" ) );
      else
         Console.WriteLine( "The collection does not contain \"orange\"." );

   }

   public static void PrintValues( IEnumerable myCol )  {
      foreach ( Object obj in myCol )
         Console.WriteLine( "   {0}", obj );
      Console.WriteLine();
   }

}

/*
This code produces the following output.

Initial contents of the StringCollection:
   RED
   orange
   yellow
   RED
   green
   blue
   RED
   indigo
   violet
   RED

The collection contains "orange" at index 1.

*/

import System.* ;
import System.Collections.* ;
import System.Collections.Specialized.* ;

public class SamplesStringCollection
{
    public static void main(String[] args)
    {
        // Creates and initializes a new StringCollection.
        StringCollection myCol =  new StringCollection();
        String myArr[] = new String[]{"RED", "orange", "yellow", "RED",
            "green", "blue", "RED", "indigo", "violet", "RED"};
        myCol.AddRange(myArr);
            
        Console.WriteLine("Initial contents of the StringCollection:");
        PrintValues(myCol);
            
        // Checks whether the collection contains "orange" and, if so,
        // displays its index.
        if ( myCol.Contains("orange")) {
            Console.WriteLine("The collection contains \"orange\" at index"
                + " {0}.",System.Convert.ToString(myCol.IndexOf("orange")));
        }
        else {        
            Console.WriteLine("The collection does not contain \"orange\".");
        } 
    } //main        
        
    public static void PrintValues(IEnumerable myCol)
    {
        Object obj = null;
        IEnumerator objEnum = myCol.GetEnumerator();

        while (objEnum.MoveNext()) {        
            obj = objEnum.get_Current();
            Console.WriteLine("   {0}", obj);
        }

        Console.WriteLine();
    } //PrintValues
} //SamplesStringCollection 

/*
This code produces the following output.

Initial contents of the StringCollection:
   RED
   orange
   yellow
   RED
   green
   blue
   RED
   indigo
   violet
   RED

The collection contains "orange" at index 1.

*/

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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