Export (0) Print
Expand All

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

Searches for the specified substring and returns the zero-based index of the last occurrence within the section of the source string that extends from the beginning of the string to the specified index using the specified CompareOptions value.

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

public virtual int LastIndexOf(
	string source,
	string value,
	int startIndex,
	CompareOptions options
)

Parameters

source
Type: System.String

The string to search.

value
Type: System.String

The string to locate within source.

startIndex
Type: System.Int32

The zero-based starting index of the backward search.

options
Type: System.Globalization.CompareOptions

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

Type: System.Int32
The zero-based index of the last occurrence of value within the section of source that extends from the beginning of source to startIndex using the specified CompareOptions value, if found; otherwise, -1.

ExceptionCondition
ArgumentNullException

source is null.

-or-

value is null.

ArgumentOutOfRangeException

startIndex is outside the range of valid indexes for source.

ArgumentException

options contains an invalid CompareOptions value.

The source string is searched backward starting at startIndex 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 portion of a string. Note that IndexOf and LastIndexOf are searching in different portions of the string, even with the same startIndex parameter.

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 = 20;
      // myT1 is the string used for padding.
      String myT1;

      // Searches for the ligature Æ.
      String myStr = "Is AE or ae the same as Æ or æ?";
      Console.WriteLine();

      myT1 = new String( '-', iS );
      Console.WriteLine( "IndexOf( String, *, {0}, * )", iS );
      Console.WriteLine( "Original      : {0}", myStr );
      Console.WriteLine( "No options    : {0}{1}", myT1, myStr.Substring( iS ) );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE", iS ), -1 );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae", iS ), -1 );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ', iS ), -1 );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ', iS ), -1 );
      Console.WriteLine( "Ordinal       : {0}{1}", myT1, myStr.Substring( iS ) );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE", iS, CompareOptions.Ordinal ), -1 );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae", iS, CompareOptions.Ordinal ), -1 );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ', iS, CompareOptions.Ordinal ), -1 );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ', iS, CompareOptions.Ordinal ), -1 );
      Console.WriteLine( "IgnoreCase    : {0}{1}", myT1, myStr.Substring( iS ) );
      PrintMarker( "           AE : ", myComp.IndexOf( myStr, "AE", iS, CompareOptions.IgnoreCase ), -1 );
      PrintMarker( "           ae : ", myComp.IndexOf( myStr, "ae", iS, CompareOptions.IgnoreCase ), -1 );
      PrintMarker( "            Æ : ", myComp.IndexOf( myStr, 'Æ', iS, CompareOptions.IgnoreCase ), -1 );
      PrintMarker( "            æ : ", myComp.IndexOf( myStr, 'æ', iS, CompareOptions.IgnoreCase ), -1 );

      myT1 = new String( '-', myStr.Length - iS - 1 );
      Console.WriteLine( "LastIndexOf( String, *, {0}, * )", iS );
      Console.WriteLine( "Original      : {0}", myStr );
      Console.WriteLine( "No options    : {0}{1}", myStr.Substring( 0, iS + 1 ), myT1 );
      PrintMarker( "           AE : ", -1, myComp.LastIndexOf( myStr, "AE", iS ) );
      PrintMarker( "           ae : ", -1, myComp.LastIndexOf( myStr, "ae", iS ) );
      PrintMarker( "            Æ : ", -1, myComp.LastIndexOf( myStr, 'Æ', iS ) );
      PrintMarker( "            æ : ", -1, myComp.LastIndexOf( myStr, 'æ', iS ) );
      Console.WriteLine( "Ordinal       : {0}{1}", myStr.Substring( 0, iS + 1 ), myT1 );
      PrintMarker( "           AE : ", -1, myComp.LastIndexOf( myStr, "AE", iS, CompareOptions.Ordinal ) );
      PrintMarker( "           ae : ", -1, myComp.LastIndexOf( myStr, "ae", iS, CompareOptions.Ordinal ) );
      PrintMarker( "            Æ : ", -1, myComp.LastIndexOf( myStr, 'Æ', iS, CompareOptions.Ordinal ) );
      PrintMarker( "            æ : ", -1, myComp.LastIndexOf( myStr, 'æ', iS, CompareOptions.Ordinal ) );
      Console.WriteLine( "IgnoreCase    : {0}{1}", myStr.Substring( 0, iS + 1 ), myT1 );
      PrintMarker( "           AE : ", -1, myComp.LastIndexOf( myStr, "AE", iS, CompareOptions.IgnoreCase ) );
      PrintMarker( "           ae : ", -1, myComp.LastIndexOf( myStr, "ae", iS, CompareOptions.IgnoreCase ) );
      PrintMarker( "            Æ : ", -1, myComp.LastIndexOf( myStr, 'Æ', iS, CompareOptions.IgnoreCase ) );
      PrintMarker( "            æ : ", -1, myComp.LastIndexOf( myStr, 'æ', iS, 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();

      myT1 = new String( '-', iS );
      Console.WriteLine( "IndexOf( String, *, {0}, * )", iS );
      Console.WriteLine( "Original      : {0}", myStr );
      Console.WriteLine( "No options    : {0}{1}", myT1, myStr.Substring( iS ) );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308", iS ), -1 );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308", iS ), -1 );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü', iS ), -1 );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü', iS ), -1 );
      Console.WriteLine( "Ordinal       : {0}{1}", myT1, myStr.Substring( iS ) );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308", iS, CompareOptions.Ordinal ), -1 );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308", iS, CompareOptions.Ordinal ), -1 );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü', iS, CompareOptions.Ordinal ), -1 );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü', iS, CompareOptions.Ordinal ), -1 );
      Console.WriteLine( "IgnoreCase    : {0}{1}", myT1, myStr.Substring( iS ) );
      PrintMarker( "           U\u0308 : ", myComp.IndexOf( myStr, "U\u0308", iS, CompareOptions.IgnoreCase ), -1 );
      PrintMarker( "           u\u0308 : ", myComp.IndexOf( myStr, "u\u0308", iS, CompareOptions.IgnoreCase ), -1 );
      PrintMarker( "            Ü : ", myComp.IndexOf( myStr, 'Ü', iS, CompareOptions.IgnoreCase ), -1 );
      PrintMarker( "            ü : ", myComp.IndexOf( myStr, 'ü', iS, CompareOptions.IgnoreCase ), -1 );

      myT1 = new String( '-', myStr.Length - iS - 1 );
      Console.WriteLine( "LastIndexOf( String, *, {0}, * )", iS );
      Console.WriteLine( "Original      : {0}", myStr );
      Console.WriteLine( "No options    : {0}{1}", myStr.Substring( 0, iS + 1 ), myT1 );
      PrintMarker( "           U\u0308 : ", -1, myComp.LastIndexOf( myStr, "U\u0308", iS ) );
      PrintMarker( "           u\u0308 : ", -1, myComp.LastIndexOf( myStr, "u\u0308", iS ) );
      PrintMarker( "            Ü : ", -1, myComp.LastIndexOf( myStr, 'Ü', iS ) );
      PrintMarker( "            ü : ", -1, myComp.LastIndexOf( myStr, 'ü', iS ) );
      Console.WriteLine( "Ordinal       : {0}{1}", myStr.Substring( 0, iS + 1 ), myT1 );
      PrintMarker( "           U\u0308 : ", -1, myComp.LastIndexOf( myStr, "U\u0308", iS, CompareOptions.Ordinal ) );
      PrintMarker( "           u\u0308 : ", -1, myComp.LastIndexOf( myStr, "u\u0308", iS, CompareOptions.Ordinal ) );
      PrintMarker( "            Ü : ", -1, myComp.LastIndexOf( myStr, 'Ü', iS, CompareOptions.Ordinal ) );
      PrintMarker( "            ü : ", -1, myComp.LastIndexOf( myStr, 'ü', iS, CompareOptions.Ordinal ) );
      Console.WriteLine( "IgnoreCase    : {0}{1}", myStr.Substring( 0, iS + 1 ), myT1 );
      PrintMarker( "           U\u0308 : ", -1, myComp.LastIndexOf( myStr, "U\u0308", iS, CompareOptions.IgnoreCase ) );
      PrintMarker( "           u\u0308 : ", -1, myComp.LastIndexOf( myStr, "u\u0308", iS, CompareOptions.IgnoreCase ) );
      PrintMarker( "            Ü : ", -1, myComp.LastIndexOf( myStr, 'Ü', iS, CompareOptions.IgnoreCase ) );
      PrintMarker( "            ü : ", -1, myComp.LastIndexOf( myStr, 'ü', iS, 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.

IndexOf( String, *, 20, * )
Original      : Is AE or ae the same as Æ or æ?
No options    : -------------------- as Æ or æ?
           AE :                         f
           ae :                              f
            Æ :                         f
            æ :                              f
Ordinal       : -------------------- as Æ or æ?
           AE :
           ae :
            Æ :                         f
            æ :                              f
IgnoreCase    : -------------------- as Æ or æ?
           AE :                         f
           ae :                         f
            Æ :                         f
            æ :                         f
LastIndexOf( String, *, 20, * )
Original      : Is AE or ae the same as Æ or æ?
No options    : Is AE or ae the same ----------
           AE :    l
           ae :          l
            Æ :    l
            æ :          l
Ordinal       : Is AE or ae the same ----------
           AE :    l
           ae :          l
            Æ :
            æ :
IgnoreCase    : Is AE or ae the same ----------
           AE :          l
           ae :          l
            Æ :          l
            æ :          l

IndexOf( String, *, 20, * )
Original      : Is U" or u" the same as Ü or ü?
No options    : -------------------- as Ü or ü?
           U" :                         f
           u" :                              f
            Ü :                         f
            ü :                              f
Ordinal       : -------------------- as Ü or ü?
           U" :
           u" :
            Ü :                         f
            ü :                              f
IgnoreCase    : -------------------- as Ü or ü?
           U" :                         f
           u" :                         f
            Ü :                         f
            ü :                         f
LastIndexOf( String, *, 20, * )
Original      : Is U" or u" the same as Ü or ü?
No options    : Is U" or u" the same ----------
           U" :    l
           u" :          l
            Ü :    l
            ü :          l
Ordinal       : Is U" or u" the same ----------
           U" :    l
           u" :          l
            Ü :
            ü :
IgnoreCase    : Is U" or u" the same ----------
           U" :          l
           u" :          l
            Ü :          l
            ü :          l

*/

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Community Additions

ADD
Show:
© 2014 Microsoft