StringCollection.IndexOf(String) メソッド

定義

指定した文字列を検索し、StringCollection 内でその文字列が最初に見つかった位置の 0 から始まるインデックスを返します。Searches for the specified string and returns the zero-based index of the first occurrence within the StringCollection.

public:
 int IndexOf(System::String ^ value);
public int IndexOf (string value);
member this.IndexOf : string -> int
Public Function IndexOf (value As String) As Integer

パラメーター

value
String

検索される文字列。The string to locate. 値として null を指定できます。The value can be null.

戻り値

StringCollection 内で value が見つかった場合は、最初に見つかった位置の 0 から始まるインデックス。それ以外の場合は -1。The zero-based index of the first occurrence of value in the StringCollection, if found; otherwise, -1.

次のコード例ではStringCollection 、で要素を検索します。The following code example searches the StringCollection for an element.

#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;
void PrintValues( IEnumerable^ myCol );
int main()
{
   
   // Creates and initializes a new StringCollection.
   StringCollection^ myCol = gcnew StringCollection;
   array<String^>^myArr = {"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\"." );
}

void PrintValues( IEnumerable^ myCol )
{
   IEnumerator^ myEnum = myCol->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      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.

*/
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.

*/
Imports System.Collections
Imports System.Collections.Specialized

Public Class SamplesStringCollection   

   Public Shared Sub Main()

      ' Creates and initializes a new StringCollection.
      Dim myCol As New StringCollection()
      Dim myArr() As [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") Then
         Console.WriteLine("The collection contains ""orange"" at index {0}.", myCol.IndexOf("orange"))
      Else
         Console.WriteLine("The collection does not contain ""orange"".")
      End If 

   End Sub

   Public Shared Sub PrintValues(myCol As IEnumerable)
      Dim obj As [Object]
      For Each obj In  myCol
         Console.WriteLine("   {0}", obj)
      Next obj
      Console.WriteLine()
   End Sub

End Class


'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.
'

注釈

このメソッドは、を呼びObject.Equals出すことによって等価性を判断します。This method determines equality by calling Object.Equals. 文字列比較では大文字と小文字が区別されます。String comparisons are case-sensitive.

このメソッドは、線形検索を実行します。したがって、このメソッドは O (n) 演算です。 nここCountで、はです。This method performs a linear search; therefore, this method is an O(n) operation, where n is Count.

.NET Framework 2.0 以降では、このメソッドは、コレクションのオブジェクトEqualsCompareToメソッドitemを使用して、項目が存在するかどうかを判断します。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. 以前のバージョンの .NET Framework では、この決定は、コレクション内のEqualsオブジェクトCompareToitemパラメーターのメソッドとメソッドを使用して行われていました。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.

適用対象

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