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CompareInfo.LastIndexOf Method (String, String, CompareOptions)

Searches for the specified substring and returns the zero-based index of the last occurrence within the entire source string using the specified CompareOptions value.

Namespace: System.Globalization
Assembly: mscorlib (in mscorlib.dll)

public virtual int LastIndexOf (
	string source,
	string value,
	CompareOptions options
)
public int LastIndexOf (
	String source, 
	String value, 
	CompareOptions options
)
public function LastIndexOf (
	source : String, 
	value : String, 
	options : CompareOptions
) : int
Not applicable.

Parameters

source

The string to search.

value

The string to locate within source.

options

The CompareOptions value that defines how source and value should be compared. options is either the value Ordinal used by itself, or the bitwise combination of one or more of the following values: IgnoreCase, IgnoreSymbols, IgnoreNonSpace, IgnoreWidth, and IgnoreKanaType.

Return Value

The zero-based index of the last occurrence of value within the entire source using the specified CompareOptions value, if found; otherwise, -1.

Exception typeCondition

ArgumentNullException

source is a null reference (Nothing in Visual Basic).

-or-

value is a null reference (Nothing in Visual Basic).

ArgumentException

options contains an invalid CompareOptions value.

The source string is searched backward starting at the end of the string and ending at the beginning of the string.

The CompareOptions.StringSort value is not valid for this method.

If options does not include the Ordinal value, this overload performs a culture-sensitive search. A Unicode value representing a precomposed character, such as the ligature "Æ" (U+00C6), might be considered equivalent to any occurrence of the character's components in the correct sequence, such as "AE" (U+0041, U+0045), depending on the culture. If options includes the Ordinal value, this overload performs an ordinal (culture-insensitive) search, where the Unicode values are compared.

The following code example determines the indexes of the first and last occurrences of a character or a substring within a string.

using System;
using System.Globalization;

public class SamplesCompareInfo  {

   public static void Main()  {

      // Creates CompareInfo for the InvariantCulture.
      CompareInfo myComp = CultureInfo.InvariantCulture.CompareInfo;

      // Searches for the ligature Æ.
      String myStr = "Is AE or ae the same as Æ or æ?";
      Console.WriteLine();
      Console.WriteLine( "No options    : {0}", myStr );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE" ), myComp.LastIndexOf( myStr, "AE" ) );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae" ), myComp.LastIndexOf( myStr, "ae" ) );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ' ), myComp.LastIndexOf( myStr, 'Æ' ) );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ' ), myComp.LastIndexOf( myStr, 'æ' ) );
      Console.WriteLine( "Ordinal       : {0}", myStr );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE", CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, "AE", CompareOptions.Ordinal ) );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae", CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, "ae", CompareOptions.Ordinal ) );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ', CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, 'Æ', CompareOptions.Ordinal ) );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ', CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, 'æ', CompareOptions.Ordinal ) );
      Console.WriteLine( "IgnoreCase    : {0}", myStr );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE", CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, "AE", CompareOptions.IgnoreCase ) );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae", CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, "ae", CompareOptions.IgnoreCase ) );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ', CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, 'Æ', CompareOptions.IgnoreCase ) );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ', CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, 'æ', CompareOptions.IgnoreCase ) );

      // Searches for the combining character sequence Latin capital letter U with diaeresis or Latin small letter u with diaeresis.
      myStr = "Is \u0055\u0308 or \u0075\u0308 the same as \u00DC or \u00FC?";
      Console.WriteLine();
      Console.WriteLine( "No options    : {0}", myStr );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308" ), myComp.LastIndexOf( myStr, "U\u0308" ) );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308" ), myComp.LastIndexOf( myStr, "u\u0308" ) );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü' ), myComp.LastIndexOf( myStr, 'Ü' ) );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü' ), myComp.LastIndexOf( myStr, 'ü' ) );
      Console.WriteLine( "Ordinal       : {0}", myStr );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308", CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, "U\u0308", CompareOptions.Ordinal ) );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308", CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, "u\u0308", CompareOptions.Ordinal ) );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü', CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, 'Ü', CompareOptions.Ordinal ) );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü', CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, 'ü', CompareOptions.Ordinal ) );
      Console.WriteLine( "IgnoreCase    : {0}", myStr );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308", CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, "U\u0308", CompareOptions.IgnoreCase ) );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308", CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, "u\u0308", CompareOptions.IgnoreCase ) );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü', CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, 'Ü', CompareOptions.IgnoreCase ) );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü', CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, 'ü', CompareOptions.IgnoreCase ) );

   }

   public static void PrintMarker( String Prefix, int First, int Last )  {

      // Determines the size of the array to create.
      int mySize;
      if ( Last > First )
         mySize = Last;
      else
         mySize = First;

      if ( mySize > -1 )  {

         // Creates an array of Char to hold the markers.
         Char[] myCharArr = new Char[mySize+1];

         // Inserts the appropriate markers.
         if ( First > -1 )
         myCharArr[First] = 'f';
         if ( Last > -1 )
            myCharArr[Last] = 'l';
         if ( First == Last )
         myCharArr[First] = 'b';

         // Displays the array of Char as a String.
         Console.WriteLine( "{0}{1}", Prefix, new String( myCharArr ) );

      }
      else
         Console.WriteLine( Prefix );

   }

}


/*
This code produces the following output.

No options    : Is AE or ae the same as Æ or æ?
           AE :    f                    l
           ae :          f                   l
            Æ :    f                    l
            æ :          f                   l
Ordinal       : Is AE or ae the same as Æ or æ?
           AE :    b
           ae :          b
            Æ :                         b
            æ :                              b
IgnoreCase    : Is AE or ae the same as Æ or æ?
           AE :    f                         l
           ae :    f                         l
            Æ :    f                         l
            æ :    f                         l

No options    : Is U" or u" the same as Ü or ü?
           U" :    f                    l
           u" :          f                   l
            Ü :    f                    l
            ü :          f                   l
Ordinal       : Is U" or u" the same as Ü or ü?
           U" :    b
           u" :          b
            Ü :                         b
            ü :                              b
IgnoreCase    : Is U" or u" the same as Ü or ü?
           U" :    f                         l
           u" :    f                         l
            Ü :    f                         l
            ü :    f                         l

*/

import System.* ;
import System.Globalization.* ;

public class SamplesCompareInfo
{
       public static void main(String[] args)
    {
        // Creates CompareInfo for the InvariantCulture.
        CompareInfo myComp = 
            CultureInfo.get_InvariantCulture().get_CompareInfo();

        // Searches for the ligature .
        String myStr = "Is AE or ae the same as Æ or æ ?";
        Console.WriteLine();
        Console.WriteLine("No options    : {0}", myStr);
        PrintMarker("           AE : ", myComp.IndexOf(myStr, "AE"), 
            myComp.LastIndexOf(myStr, "AE"));
        PrintMarker("           ae : ", myComp.IndexOf(myStr, "ae"),
            myComp.LastIndexOf(myStr, "ae"));
        PrintMarker("            Æ : ", myComp.IndexOf(myStr, 'Æ'),
            myComp.LastIndexOf(myStr , 'Æ'));
        PrintMarker("            æ : ", myComp.IndexOf(myStr , 'æ'), 
            myComp.LastIndexOf(myStr, 'æ'));
        Console.WriteLine("Ordinal       : {0}", myStr);
        PrintMarker("           AE : ", myComp.IndexOf(myStr, "AE", 
            CompareOptions.Ordinal), myComp.LastIndexOf(myStr, "AE",
            CompareOptions.Ordinal));
        PrintMarker("           ae : ", myComp.IndexOf(myStr, "ae", 
            CompareOptions.Ordinal), myComp.LastIndexOf(myStr, "ae", 
            CompareOptions.Ordinal));
        PrintMarker("            Æ : ", myComp.IndexOf(myStr, 'Æ', 
            CompareOptions.Ordinal), myComp.LastIndexOf(myStr, 'Æ', 
            CompareOptions.Ordinal));
        PrintMarker("            æ : ", myComp.IndexOf(myStr, 'æ', 
            CompareOptions.Ordinal), myComp.LastIndexOf(myStr, 'æ', 
            CompareOptions.Ordinal));
        Console.WriteLine("IgnoreCase    : {0}", myStr);
        PrintMarker("           AE : ", myComp.IndexOf(myStr, "AE", 
            CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, "AE", 
            CompareOptions.IgnoreCase));
        PrintMarker("           ae : ", myComp.IndexOf(myStr, "ae", 
            CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, "ae", 
            CompareOptions.IgnoreCase));
        PrintMarker("            Æ : ", myComp.IndexOf(myStr, 'Æ', 
            CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, 'Æ', 
            CompareOptions.IgnoreCase));
        PrintMarker("            æ : ", myComp.IndexOf(myStr, 'æ', 
            CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, 'æ', 
            CompareOptions.IgnoreCase));

        // Searches for the combining character sequence Latin capital letter 
        // U with diaeresis or Latin small letter u with diaeresis.
        myStr = "Is \u0055\u0308 or \u0075\u0308 the same as \u00DC or \u00FC?";
        Console.WriteLine();
        Console.WriteLine("No options    : {0}", myStr);
        PrintMarker("           U\u0308 : ", myComp.IndexOf(myStr, "U\u0308"),
            myComp.LastIndexOf(myStr, "U\u0308"));
        PrintMarker("           u\u0308 : ", myComp.IndexOf(myStr, "u\u0308"), 
            myComp.LastIndexOf(myStr, "u\u0308"));
        PrintMarker("           Ü  : ", myComp.IndexOf(myStr, 'Ü'), 
            myComp.LastIndexOf(myStr, 'Ü'));
        PrintMarker("            ü : ", myComp.IndexOf(myStr,'ü'),
            myComp.LastIndexOf(myStr,'ü'));
        Console.WriteLine("Ordinal       : {0}", myStr);
        PrintMarker("           U\u0308 : ", myComp.IndexOf(myStr, "U\u0308",
            CompareOptions.Ordinal), myComp.LastIndexOf(myStr, "U\u0308", 
            CompareOptions.Ordinal));
        PrintMarker("           u\u0308 : ", myComp.IndexOf(myStr, "u\u0308", 
            CompareOptions.Ordinal), myComp.LastIndexOf(myStr, "u\u0308", 
            CompareOptions.Ordinal));
        PrintMarker("            Ü : ", myComp.IndexOf(myStr, 'Ü', 
            CompareOptions.Ordinal), myComp.LastIndexOf(myStr, 'Ü',
            CompareOptions.Ordinal));
        PrintMarker("            ü : ", myComp.IndexOf(myStr, 'ü', 
            CompareOptions.Ordinal), myComp.LastIndexOf(myStr, 'ü', 
            CompareOptions.Ordinal));
        Console.WriteLine("IgnoreCase    : {0}", myStr);
        PrintMarker("           U\u0308 : ", myComp.IndexOf(myStr, "U\u0308",
            CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, "U\u0308", 
            CompareOptions.IgnoreCase));
        PrintMarker("           u\u0308 : ", myComp.IndexOf(myStr, "u\u0308",
            CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, "u\u0308", 
            CompareOptions.IgnoreCase));
        PrintMarker("            Ü : ", myComp.IndexOf(myStr, 'Ü',
            CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, 'Ü', 
            CompareOptions.IgnoreCase));
        PrintMarker("            ü : ", myComp.IndexOf(myStr, 'ü', 
            CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, 'ü',
            CompareOptions.IgnoreCase));
    } //main
   
    public static void PrintMarker(String Prefix, int First, int Last)
    {
        // Determines the size of the array to create.
        int mySize;
        if (Last > First) {
            mySize = Last;
        }
        else {
            mySize = First;
        } 
        if (mySize > -1) {
            // Creates an array of Char to hold the markers.
            char myCharArr[] = new char[mySize + 1];
                
            // Inserts the appropriate markers.
            if (First > -1) {
            myCharArr[First] = 'f';
            }
            if (Last > -1) {
                myCharArr[Last] = 'l';
            }
            if (First == Last) {
                myCharArr[First] = 'b';
            }
                
            // Displays the array of Char as a String.
            Console.WriteLine("{0}{1} ", Prefix,new String( myCharArr));
        }
        else {
            Console.WriteLine(Prefix);
        } 
    } //PrintMarker
} //SamplesCompareInfo

/*
This code produces the following output.

No options    : Is AE or ae the same as Æ or æ ?
           AE :    f                    l
           ae :          f                   l
            Æ :    f                    l
            æ :          f                   l
Ordinal       : Is AE or ae the same as Æ or æ ?
           AE :    b
           ae :          b
            Æ :                         b
            æ :                              b
IgnoreCase    : Is AE or ae the same as Æ or æ ?
           AE :    f                         l
           ae :    f                         l
            Æ :    f                         l
            æ :    f                         l

No options    : Is U" or u" the same as Ü or ü?
           U" :    f                    l
           u" :          f                   l
           Ü  :    f                    l
            ü :          f                   l
Ordinal       : Is U" or u" the same as Ü or ü?
           U" :    b
           u" :          b
            Ü :                         b
            ü :                              b
IgnoreCase    : Is U" or u" the same as Ü or ü?
           U" :    f                         l
           u" :    f                         l
            Ü :    f                         l
            ü :    f                         l
*/

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

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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