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CompareInfo.LastIndexOf Method (String, Char, Int32, Int32)

Searches for the specified character and returns the zero-based index of the last occurrence within the section of the source string that contains the specified number of elements and ends at the specified index.

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

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

Parameters

source

The string to search.

value

The character to locate within source.

startIndex

The zero-based starting index of the backward search.

count

The number of elements in the section to search.

Return Value

The zero-based index of the last occurrence of value within the section of source that contains the number of elements specified by count and ends at startIndex, if found; otherwise, -1.
Exception typeCondition

ArgumentNullException

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

ArgumentOutOfRangeException

startIndex is outside the range of valid indexes for source.

-or-

count is less than zero.

-or-

startIndex and count do not specify a valid section in source.

The source string is searched backward starting at startIndex and ending at startIndex - count + 1.

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 portion of a string.

using System;
using System.Globalization;

public class SamplesCompareInfo  {

   public static void Main()  {

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

      // iS is the starting index of the substring.
      int iS = 8;
      // iL is the length of the substring.
      int iL = 18;
      // myT1 and myT2 are the strings used for padding.
      String myT1 = new String( '-', iS );
      String myT2;

      // Searches for the ligature Æ.
      String myStr = "Is AE or ae the same as Æ or æ?";
      myT2 = new String( '-', myStr.Length - iS - iL );
      Console.WriteLine();
      Console.WriteLine( "Original      : {0}", myStr );
      Console.WriteLine( "No options    : {0}{1}{2}", myT1, myStr.Substring( iS, iL ), myT2 );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE", iS, iL ), myComp.LastIndexOf( myStr, "AE", iS + iL - 1, iL ) );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae", iS, iL ), myComp.LastIndexOf( myStr, "ae", iS + iL - 1, iL ) );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ', iS, iL ), myComp.LastIndexOf( myStr, 'Æ', iS + iL - 1, iL ) );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ', iS, iL ), myComp.LastIndexOf( myStr, 'æ', iS + iL - 1, iL ) );
      Console.WriteLine( "Ordinal       : {0}{1}{2}", myT1, myStr.Substring( iS, iL ), myT2 );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE", iS, iL, CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, "AE", iS + iL - 1, iL, CompareOptions.Ordinal ) );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae", iS, iL, CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, "ae", iS + iL - 1, iL, CompareOptions.Ordinal ) );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ', iS, iL, CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, 'Æ', iS + iL - 1, iL, CompareOptions.Ordinal ) );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ', iS, iL, CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, 'æ', iS + iL - 1, iL, CompareOptions.Ordinal ) );
      Console.WriteLine( "IgnoreCase    : {0}{1}{2}", myT1, myStr.Substring( iS, iL ), myT2 );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE", iS, iL, CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, "AE", iS + iL - 1, iL, CompareOptions.IgnoreCase ) );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae", iS, iL, CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, "ae", iS + iL - 1, iL, CompareOptions.IgnoreCase ) );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ', iS, iL, CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, 'Æ', iS + iL - 1, iL, CompareOptions.IgnoreCase ) );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ', iS, iL, CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, 'æ', iS + iL - 1, iL, 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?";
      myT2 = new String( '-', myStr.Length - iS - iL );
      Console.WriteLine();
      Console.WriteLine( "Original      : {0}", myStr );
      Console.WriteLine( "No options    : {0}{1}{2}", myT1, myStr.Substring( iS, iL ), myT2 );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308", iS, iL ), myComp.LastIndexOf( myStr, "U\u0308", iS + iL - 1, iL ) );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308", iS, iL ), myComp.LastIndexOf( myStr, "u\u0308", iS + iL - 1, iL ) );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü', iS, iL ), myComp.LastIndexOf( myStr, 'Ü', iS + iL - 1, iL ) );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü', iS, iL ), myComp.LastIndexOf( myStr, 'ü', iS + iL - 1, iL ) );
      Console.WriteLine( "Ordinal       : {0}{1}{2}", myT1, myStr.Substring( iS, iL ), myT2 );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308", iS, iL, CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, "U\u0308", iS + iL - 1, iL, CompareOptions.Ordinal ) );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308", iS, iL, CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, "u\u0308", iS + iL - 1, iL, CompareOptions.Ordinal ) );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü', iS, iL, CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, 'Ü', iS + iL - 1, iL, CompareOptions.Ordinal ) );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü', iS, iL, CompareOptions.Ordinal ), myComp.LastIndexOf( myStr, 'ü', iS + iL - 1, iL, CompareOptions.Ordinal ) );
      Console.WriteLine( "IgnoreCase    : {0}{1}{2}", myT1, myStr.Substring( iS, iL ), myT2 );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308", iS, iL, CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, "U\u0308", iS + iL - 1, iL, CompareOptions.IgnoreCase ) );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308", iS, iL, CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, "u\u0308", iS + iL - 1, iL, CompareOptions.IgnoreCase ) );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü', iS, iL, CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, 'Ü', iS + iL - 1, iL, CompareOptions.IgnoreCase ) );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü', iS, iL, CompareOptions.IgnoreCase ), myComp.LastIndexOf( myStr, 'ü', iS + iL - 1, iL, 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.

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

Original      : Is U" or u" the same as Ü or ü?
No options    : -------- u" the same as Ü -----
           U" :                         b
           u" :          b
            Ü :                         b
            ü :          b
Ordinal       : -------- u" the same as Ü -----
           U" :
           u" :          b
            Ü :                         b
            ü :
IgnoreCase    : -------- u" the same as 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();

		// iS is the starting index of the substring.
		int iS = 8;
		// iL is the length of the substring.
		int iL = 18;
		// myT1 and myT2 are the strings used for padding.
		String myT1 =  new String('-', iS);
		String myT2;

		// Searches for the ligature .
		String myStr = "Is AE or ae the same as Æ or æ?";
		myT2 = new String('-', myStr.length() - iS - iL);
		Console.WriteLine();
		Console.WriteLine("Original      : {0}", myStr);
		Console.WriteLine("No options    : {0}{1}{2}", 
			myT1, myStr.Substring(iS, iL), myT2);
		PrintMarker("           AE : ", myComp.IndexOf(myStr, "AE", iS, iL), 
			myComp.LastIndexOf(myStr, "AE", iS + iL - 1, iL));
		PrintMarker("           ae : ", myComp.IndexOf(myStr, "ae", iS, iL),
			myComp.LastIndexOf(myStr, "ae", iS + iL - 1, iL));
		PrintMarker("            Æ : ", myComp.IndexOf(myStr, 'Æ', iS, iL),
			myComp.LastIndexOf(myStr, 'Æ', iS + iL - 1, iL));
		PrintMarker("            æ : ", myComp.IndexOf(myStr,'æ', iS, iL),
			myComp.LastIndexOf(myStr, 'æ', iS + iL - 1, iL));
		Console.WriteLine("Ordinal       : {0}{1}{2}", myT1, 
			myStr.Substring(iS, iL), myT2);
		PrintMarker("           AE : ", myComp.IndexOf(myStr, "AE", iS, iL, 
			CompareOptions.Ordinal), myComp.LastIndexOf(myStr, "AE", 
			iS + iL - 1, iL, CompareOptions.Ordinal));
		PrintMarker("           ae : ", myComp.IndexOf(myStr, "ae", iS, iL,
			CompareOptions.Ordinal), myComp.LastIndexOf(myStr, "ae", 
			iS + iL - 1, iL, CompareOptions.Ordinal));
		PrintMarker("            Æ : ", myComp.IndexOf(myStr, 'Æ', iS, iL, 
			CompareOptions.Ordinal), myComp.LastIndexOf(myStr, 'Æ', 
			iS + iL - 1, iL, CompareOptions.Ordinal));
		PrintMarker("            æ : ", myComp.IndexOf(myStr, 'æ', iS, iL,
			CompareOptions.Ordinal), myComp.LastIndexOf(myStr,'æ', 
			iS + iL - 1, iL, CompareOptions.Ordinal));
		Console.WriteLine("IgnoreCase    : {0}{1}{2}", myT1,
			myStr.Substring(iS, iL), myT2);
		PrintMarker("           AE : ", myComp.IndexOf(myStr, "AE", iS, iL, 
			CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, "AE", 
			iS + iL - 1, iL, CompareOptions.IgnoreCase));
		PrintMarker("           ae : ", myComp.IndexOf(myStr, "ae", iS, iL, 
			CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, "ae", 
			iS + iL - 1, iL, CompareOptions.IgnoreCase));
		PrintMarker("            Æ : ", myComp.IndexOf(myStr, 'Æ', iS, iL, 
			CompareOptions.IgnoreCase), myComp.LastIndexOf(myStr, 'Æ', 
			iS + iL - 1, iL, CompareOptions.IgnoreCase));
		PrintMarker("            æ : ", myComp.IndexOf(myStr, 'æ', iS, iL, 
			CompareOptions.IgnoreCase),
			myComp.LastIndexOf(myStr, 'æ', 
			iS + iL - 1, iL, 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?";
		myT2 = new String('-', myStr.length() - iS - iL);
		Console.WriteLine();
		Console.WriteLine("Original      : {0}", myStr);
		Console.WriteLine("No options    : {0}{1}{2}", myT1, 
			myStr.Substring(iS, iL), myT2);
		PrintMarker("           U\u0308 : ", 
			myComp.IndexOf(myStr, "U\u0308", iS, iL), 
			myComp.LastIndexOf(myStr, "U\u0308", iS + iL - 1, iL));
		PrintMarker("           u\u0308 : ", 
			myComp.IndexOf(myStr, "u\u0308", iS, iL), 
			myComp.LastIndexOf(myStr, "u\u0308", iS + iL - 1, iL));
		PrintMarker("            Ü : ", myComp.IndexOf(myStr,'Ü', iS, iL), 
			myComp.LastIndexOf(myStr, 'Ü', iS + iL - 1, iL));
		PrintMarker("            ü : ", myComp.IndexOf(myStr,'ü', iS, iL), 
			myComp.LastIndexOf(myStr,'ü', iS + iL - 1, iL));
		Console.WriteLine("Ordinal       : {0}{1}{2}", myT1, 
			myStr.Substring(iS, iL), myT2);
		PrintMarker("           U\u0308 : ", 
			myComp.IndexOf(myStr, "U\u0308", iS, iL, CompareOptions.Ordinal), 
			myComp.LastIndexOf(myStr, "U\u0308", iS + iL - 1, iL,
			CompareOptions.Ordinal));
		PrintMarker("           u\u0308 : ",
			myComp.IndexOf(myStr, "u\u0308", iS, iL, CompareOptions.Ordinal), 
			myComp.LastIndexOf(myStr, "u\u0308", iS + iL - 1, iL, 
			CompareOptions.Ordinal));
		PrintMarker("            Ü : ", 
			myComp.IndexOf(myStr, 'Ü', iS, iL, CompareOptions.Ordinal), 
			myComp.LastIndexOf(myStr, 'Ü', iS + iL - 1, iL, 
			CompareOptions.Ordinal));
		PrintMarker("            ü : ", 
			myComp.IndexOf(myStr, 'ü', iS, iL, CompareOptions.Ordinal), 
			myComp.LastIndexOf(myStr, 'ü', iS + iL - 1, iL, 
			CompareOptions.Ordinal));
		Console.WriteLine("IgnoreCase    : {0}{1}{2}", myT1, 
			myStr.Substring(iS, iL), myT2);
		PrintMarker("           U\u0308 : ", myComp.IndexOf(myStr, "U\u0308",
			iS, iL, CompareOptions.IgnoreCase), 
			myComp.LastIndexOf(myStr, "U\u0308", iS + iL - 1, iL, 
			CompareOptions.IgnoreCase));
		PrintMarker("           u\u0308 : ", 
			myComp.IndexOf(myStr, "u\u0308", iS, iL, CompareOptions.IgnoreCase),
			myComp.LastIndexOf(myStr, "u\u0308", iS + iL - 1, iL, 
			CompareOptions.IgnoreCase));
		PrintMarker("            Ü : ", 
			myComp.IndexOf(myStr, 'Ü', iS, iL, CompareOptions.IgnoreCase),
			myComp.LastIndexOf(myStr, 'Ü', iS + iL - 1, iL, 
			CompareOptions.IgnoreCase));
		PrintMarker("            ü : ",
			myComp.IndexOf(myStr,'ü', iS, iL, CompareOptions.IgnoreCase), 
			myComp.LastIndexOf(myStr, 'ü', iS + iL - 1, iL, 
			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.

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

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