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CompareInfo.LastIndexOf Method (String, Char)

Searches for the specified character and returns the zero-based index of the last occurrence within the entire source string.

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

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

Parameters

source

The string to search.

value

The character to locate within source.

Return Value

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

Exception typeCondition

ArgumentNullException

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

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

This overload performs a culture-sensitive search. If the character is a Unicode value representing a precomposed character, such as the ligature "Æ" (U+00C6), it might be considered equivalent to any occurrence of its components in the correct sequence, such as "AE" (U+0041, U+0045), depending on the culture. To perform an ordinal (culture-insensitive) search, where a character is considered equivalent to another character only if the Unicode values are the same, the application should use one of the overloads that accepts a CompareOptions value as a parameter and use the Ordinal value. Overloads of String.LastIndexOf that search for a character perform an ordinal search, while those that search for a string perform a culture-sensitive search.

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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