CompareOptions Enum

Reference

Definition

Namespace:: System.Globalization

Assembly:: System.Globalization.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Defines the string comparison options to use with CompareInfo.

This enumeration supports a bitwise combination of its member values.

public enum class CompareOptions

[System.Flags]
public enum CompareOptions

[System.Flags]
[System.Serializable]
public enum CompareOptions

[System.Flags]
[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public enum CompareOptions

[<System.Flags>]
type CompareOptions =

[<System.Flags>]
[<System.Serializable>]
type CompareOptions =

[<System.Flags>]
[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type CompareOptions =

Public Enum CompareOptions

Inheritance: Object

ValueType

Enum
CompareOptions

Attributes: FlagsAttribute SerializableAttribute ComVisibleAttribute

Fields

IgnoreCase	1	Indicates that the string comparison must ignore case.
IgnoreKanaType	8	Indicates that the string comparison must ignore the Kana type. Kana type refers to Japanese hiragana and katakana characters, which represent phonetic sounds in the Japanese language. Hiragana is used for native Japanese expressions and words, while katakana is used for words borrowed from other languages, such as "computer" or "Internet". A phonetic sound can be expressed in both hiragana and katakana. If this value is selected, the hiragana character for one sound is considered equal to the katakana character for the same sound.
IgnoreNonSpace	2	Indicates that the string comparison must ignore nonspacing combining characters, such as diacritics. The Unicode Standard defines combining characters as characters that are combined with base characters to produce a new character. Nonspacing combining characters do not occupy a spacing position by themselves when rendered.
IgnoreSymbols	4	Indicates that the string comparison must ignore symbols, such as white-space characters, punctuation, currency symbols, the percent sign, mathematical symbols, the ampersand, and so on.
IgnoreWidth	16	Indicates that the string comparison must ignore the character width. For example, Japanese katakana characters can be written as full-width or half-width. If this value is selected, the katakana characters written as full-width are considered equal to the same characters written as half-width.
None	0	Indicates the default option settings for string comparisons.
Ordinal	1073741824	Indicates that the string comparison must use successive Unicode UTF-16 encoded values of the string (code unit by code unit comparison), leading to a fast comparison but one that is culture-insensitive. A string starting with a code unit XXXX16 comes before a string starting with YYYY16, if XXXX16 is less than YYYY16. This value cannot be combined with other CompareOptions values and must be used alone.
OrdinalIgnoreCase	268435456	String comparison must ignore case, then perform an ordinal comparison. This technique is equivalent to converting the string to uppercase using the invariant culture and then performing an ordinal comparison on the result.
StringSort	536870912	Indicates that the string comparison must use the string sort algorithm. In a string sort, the hyphen and the apostrophe, as well as other nonalphanumeric symbols, come before alphanumeric characters.

Examples

The following code example shows how sorting with StringSort differs from sorting without StringSort.

using namespace System;
using namespace System::Collections;
using namespace System::Globalization;

// __gc public class SamplesCompareOptions {
ref class MyStringComparer: public IComparer
{
public:

   // Constructs a comparer using the specified CompareOptions.
   CompareInfo^ myComp;
   CompareOptions myOptions;
   MyStringComparer( CompareInfo^ cmpi, CompareOptions options )
      : myComp( cmpi ), myOptions( options )
   {}

   // Compares strings with the CompareOptions specified in the constructor.
   virtual int Compare( Object^ a, Object^ b )
   {
      if ( a == b )
            return 0;

      if ( a == nullptr )
            return  -1;

      if ( b == nullptr )
            return 1;

      String^ sa = dynamic_cast<String^>(a);
      String^ sb = dynamic_cast<String^>(b);
      if ( sa != nullptr && sb != nullptr )
            return myComp->Compare( sa, sb, myOptions );

      throw gcnew ArgumentException( "a and b should be strings." );
   }
};

int main()
{
   
   // Creates and initializes an array of strings to sort.
   array<String^>^myArr = {"cant","bill's","coop","cannot","billet","can't","con","bills","co-op"};
   Console::WriteLine( "\nInitially, " );
   IEnumerator^ myEnum = myArr->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ myStr = safe_cast<String^>(myEnum->Current);
      Console::WriteLine( myStr );
   }

   
   // Creates and initializes a Comparer to use.
   //CultureInfo* myCI = new CultureInfo(S"en-US", false);
   MyStringComparer^ myComp = gcnew MyStringComparer( CompareInfo::GetCompareInfo( "en-US" ),CompareOptions::None );
   
   // Sorts the array without StringSort.
   Array::Sort( myArr, myComp );
   Console::WriteLine( "\nAfter sorting without CompareOptions::StringSort:" );
   myEnum = myArr->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ myStr = safe_cast<String^>(myEnum->Current);
      Console::WriteLine( myStr );
   }

   
   // Sorts the array with StringSort.
   myComp = gcnew MyStringComparer( CompareInfo::GetCompareInfo( "en-US" ),CompareOptions::StringSort );
   Array::Sort( myArr, myComp );
   Console::WriteLine( "\nAfter sorting with CompareOptions::StringSort:" );
   myEnum = myArr->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      String^ myStr = safe_cast<String^>(myEnum->Current);
      Console::WriteLine( myStr );
   }
}

/*
This code produces the following output.

Initially,
cant
bill's
coop
cannot
billet
can't
con
bills
co-op

After sorting without CompareOptions::StringSort:
billet
bills
bill's
cannot
cant
can't
con
coop
co-op

After sorting with CompareOptions::StringSort:
bill's
billet
bills
can't
cannot
cant
co-op
con
coop
*/

using System;
using System.Collections;
using System.Globalization;

public class SamplesCompareOptions  {

   private class MyStringComparer: IComparer {
      private CompareInfo myComp;
      private CompareOptions myOptions = CompareOptions.None;

      // Constructs a comparer using the specified CompareOptions.
      public MyStringComparer( CompareInfo cmpi, CompareOptions options )  {
         myComp = cmpi;
         this.myOptions = options;
      }

      // Compares strings with the CompareOptions specified in the constructor.
      public int Compare(Object a, Object b) {
         if (a == b) return 0;
         if (a == null) return -1;
         if (b == null) return 1;

         String sa = a as String;
         String sb = b as String;
         if (sa != null && sb != null)
            return myComp.Compare(sa, sb, myOptions);
         throw new ArgumentException("a and b should be strings.");
      }
   }

   public static void Main()  {

      // Creates and initializes an array of strings to sort.
      String[] myArr = new String[9] { "cant", "bill's", "coop", "cannot", "billet", "can't", "con", "bills", "co-op" };
      Console.WriteLine( "\nInitially," );
      foreach ( String myStr in myArr )
         Console.WriteLine( myStr );

      // Creates and initializes a Comparer to use.
      //CultureInfo myCI = new CultureInfo( "en-US", false );
      MyStringComparer myComp = new MyStringComparer(CompareInfo.GetCompareInfo("en-US"), CompareOptions.None);

      // Sorts the array without StringSort.
      Array.Sort( myArr, myComp );
      Console.WriteLine( "\nAfter sorting without CompareOptions.StringSort:" );
      foreach ( String myStr in myArr )
         Console.WriteLine( myStr );

      // Sorts the array with StringSort.
      myComp = new MyStringComparer(CompareInfo.GetCompareInfo("en-US"), CompareOptions.StringSort);
      Array.Sort( myArr, myComp );
      Console.WriteLine( "\nAfter sorting with CompareOptions.StringSort:" );
      foreach ( String myStr in myArr )
         Console.WriteLine( myStr );
   }
}

/*
This code produces the following output.

Initially,
cant
bill's
coop
cannot
billet
can't
con
bills
co-op

After sorting without CompareOptions.StringSort:
billet
bills
bill's
cannot
cant
can't
con
coop
co-op

After sorting with CompareOptions.StringSort:
bill's
billet
bills
can't
cannot
cant
co-op
con
coop

*/

Imports System.Collections
Imports System.Globalization

Public Class SamplesCompareOptions

   Private Class MyStringComparer
      Implements IComparer

      Private myComp As CompareInfo
      Private myOptions As CompareOptions = CompareOptions.None
      
      ' Constructs a comparer using the specified CompareOptions.
      Public Sub New(cmpi As CompareInfo, options As CompareOptions)
         myComp = cmpi
         Me.myOptions = options
      End Sub
      
      ' Compares strings with the CompareOptions specified in the constructor.
      Public Function Compare(a As [Object], b As [Object]) As Integer Implements IComparer.Compare
         If a = b Then
            Return 0
         End If
         If a Is Nothing Then
            Return - 1
         End If
         If b Is Nothing Then
            Return 1
         End If 

         Dim sa As [String] = a
         Dim sb As [String] = b
         If Not (sa Is Nothing) And Not (sb Is Nothing) Then
            Return myComp.Compare(sa, sb, myOptions)
         End If
         Throw New ArgumentException("a and b should be strings.")

      End Function 'Compare 

   End Class


   Public Shared Sub Main()
      
      ' Creates and initializes an array of strings to sort.
      Dim myArr() As [String] = {"cant", "bill's", "coop", "cannot", "billet", "can't", "con", "bills", "co-op"}
      Console.WriteLine()
      Console.WriteLine("Initially,")
      Dim myStr As [String]
      For Each myStr In  myArr
         Console.WriteLine(myStr)
      Next myStr 

      ' Creates and initializes a Comparer to use.
      'CultureInfo myCI = new CultureInfo( "en-US", false );
      Dim myComp As New MyStringComparer(CompareInfo.GetCompareInfo("en-US"), CompareOptions.None)
      
      ' Sorts the array without StringSort.
      Array.Sort(myArr, myComp)
      Console.WriteLine()
      Console.WriteLine("After sorting without CompareOptions.StringSort:")
      For Each myStr In  myArr
         Console.WriteLine(myStr)
      Next myStr 

      ' Sorts the array with StringSort.
      myComp = New MyStringComparer(CompareInfo.GetCompareInfo("en-US"), CompareOptions.StringSort)
      Array.Sort(myArr, myComp)
      Console.WriteLine()
      Console.WriteLine("After sorting with CompareOptions.StringSort:")
      For Each myStr In  myArr
         Console.WriteLine(myStr)
      Next myStr 

   End Sub

End Class


'This code produces the following output.
'
'Initially,
'cant
'bill's
'coop
'cannot
'billet
'can't
'con
'bills
'co-op
'
'After sorting without CompareOptions.StringSort:
'billet
'bills
'bill's
'cannot
'cant
'can't
'con
'coop
'co-op
'
'After sorting with CompareOptions.StringSort:
'bill's
'billet
'bills
'can't
'cannot
'cant
'co-op
'con
'coop

Remarks

These options denote case sensitivity or necessity to ignore types of characters.

.NET uses three distinct ways of sorting: word sort, string sort, and ordinal sort. Word sort performs a culture-sensitive comparison of strings. Certain nonalphanumeric characters might have special weights assigned to them. For example, the hyphen ("-") might have a very small weight assigned to it so that "coop" and "co-op" appear next to each other in a sorted list. String sort is similar to word sort, except that there are no special cases. Therefore, all nonalphanumeric symbols come before all alphanumeric characters. Ordinal sort compares strings based on the Unicode values of each element of the string. For a downloadable set of text files that contain information on the character weights used in sorting and comparison operations for Windows operating systems, see Sorting Weight Tables. For the sort weight table for Linux and macOS, see the Default Unicode Collation Element Table. The specific version of the sort weight table on Linux and macOS depends on the version of the International Components for Unicode libraries installed on the system. For information on ICU versions and the Unicode versions that they implement, see Downloading ICU.

The StringSort value can only be used with CompareInfo.Compare and CompareInfo.GetSortKey. ArgumentException is thrown if the StringSort value is used with CompareInfo.IsPrefix, CompareInfo.IsSuffix, CompareInfo.IndexOf, or CompareInfo.LastIndexOf.

Note

When possible, you should use string comparison methods that accept a CompareOptions value to specify the kind of comparison expected. As a general rule, user-facing comparisons are best served by the use of linguistic options (using the current culture), while security comparisons should specify Ordinal or OrdinalIgnoreCase.

Notes on culture-sensitive sorts

Note

.NET Core running on Linux and macOS systems only: The collation behavior for the C and Posix cultures is always case-sensitive because these cultures do not use the expected Unicode collation order. We recommend that you use a culture other than C or Posix for performing culture-sensitive, case-insensitive sorting operations.

Applies to