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CompareInfo Class

Implements a set of methods for culture-sensitive string comparisons.

System.Object
  System.Globalization.CompareInfo

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

[SerializableAttribute]
[ComVisibleAttribute(true)]
public class CompareInfo : IDeserializationCallback

The CompareInfo type exposes the following members.

  NameDescription
Public propertySupported by the XNA FrameworkLCIDGets the properly formed culture identifier for the current CompareInfo.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsNameGets the name of the culture used for sorting operations by this CompareInfo object.
Public propertyVersionGets information about the version of Unicode used for comparing and sorting strings.
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  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCompare(String, String)Compares two strings.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCompare(String, String, CompareOptions)Compares two strings using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCompare(String, Int32, String, Int32)Compares the end section of a string with the end section of another string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCompare(String, Int32, String, Int32, CompareOptions)Compares the end section of a string with the end section of another string using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCompare(String, Int32, Int32, String, Int32, Int32)Compares a section of one string with a section of another string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsCompare(String, Int32, Int32, String, Int32, Int32, CompareOptions)Compares a section of one string with a section of another string using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsEqualsDetermines whether the specified object is equal to the current CompareInfo object. (Overrides Object.Equals(Object).)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodStatic memberSupported by the XNA FrameworkGetCompareInfo(Int32)Initializes a new CompareInfo object that is associated with the culture with the specified identifier.
Public methodStatic memberSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetCompareInfo(String)Initializes a new CompareInfo object that is associated with the culture with the specified name.
Public methodStatic memberGetCompareInfo(Int32, Assembly)Initializes a new CompareInfo object that is associated with the specified culture and that uses string comparison methods in the specified Assembly.
Public methodStatic memberGetCompareInfo(String, Assembly)Initializes a new CompareInfo object that is associated with the specified culture and that uses string comparison methods in the specified Assembly.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetHashCodeServes as a hash function for the current CompareInfo for hashing algorithms and data structures, such as a hash table. (Overrides Object.GetHashCode().)
Public methodGetSortKey(String)Gets the sort key for the specified string.
Public methodGetSortKey(String, CompareOptions)Gets a SortKey object for the specified string using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, Char)Searches for the specified character and returns the zero-based index of the first occurrence within the entire source string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, String)Searches for the specified substring and returns the zero-based index of the first occurrence within the entire source string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, Char, CompareOptions)Searches for the specified character and returns the zero-based index of the first occurrence within the entire source string using the specified CompareOptions value.
Public methodIndexOf(String, Char, Int32)Searches for the specified character and returns the zero-based index of the first occurrence within the section of the source string that extends from the specified index to the end of the string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, String, CompareOptions)Searches for the specified substring and returns the zero-based index of the first occurrence within the entire source string using the specified CompareOptions value.
Public methodIndexOf(String, String, Int32)Searches for the specified substring and returns the zero-based index of the first occurrence within the section of the source string that extends from the specified index to the end of the string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, Char, Int32, CompareOptions)Searches for the specified character and returns the zero-based index of the first occurrence within the section of the source string that extends from the specified index to the end of the string using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, Char, Int32, Int32)Searches for the specified character and returns the zero-based index of the first occurrence within the section of the source string that starts at the specified index and contains the specified number of elements.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, String, Int32, CompareOptions)Searches for the specified substring and returns the zero-based index of the first occurrence within the section of the source string that extends from the specified index to the end of the string using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, String, Int32, Int32)Searches for the specified substring and returns the zero-based index of the first occurrence within the section of the source string that starts at the specified index and contains the specified number of elements.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, Char, Int32, Int32, CompareOptions)Searches for the specified character and returns the zero-based index of the first occurrence within the section of the source string that starts at the specified index and contains the specified number of elements using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIndexOf(String, String, Int32, Int32, CompareOptions)Searches for the specified substring and returns the zero-based index of the first occurrence within the section of the source string that starts at the specified index and contains the specified number of elements using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsPrefix(String, String)Determines whether the specified source string starts with the specified prefix.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsPrefix(String, String, CompareOptions)Determines whether the specified source string starts with the specified prefix using the specified CompareOptions value.
Public methodStatic memberIsSortable(Char)Indicates whether a specified Unicode character is sortable.
Public methodStatic memberIsSortable(String)Indicates whether a specified Unicode string is sortable.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsSuffix(String, String)Determines whether the specified source string ends with the specified suffix.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsIsSuffix(String, String, CompareOptions)Determines whether the specified source string ends with the specified suffix using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(String, Char)Searches for the specified character and returns the zero-based index of the last occurrence within the entire source string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(String, String)Searches for the specified substring and returns the zero-based index of the last occurrence within the entire source string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(String, Char, CompareOptions)Searches for the specified character and returns the zero-based index of the last occurrence within the entire source string using the specified CompareOptions value.
Public methodLastIndexOf(String, Char, Int32)Searches for the specified character 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.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(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.
Public methodLastIndexOf(String, String, Int32)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.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(String, Char, Int32, CompareOptions)Searches for the specified character 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.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(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.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(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.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(String, String, Int32, Int32)Searches for the specified substring 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.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(String, Char, Int32, Int32, CompareOptions)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 using the specified CompareOptions value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsLastIndexOf(String, String, Int32, 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 contains the specified number of elements and ends at the specified index using the specified CompareOptions value.
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibrarySupported in .NET for Windows Store appsToStringReturns a string that represents the current CompareInfo object. (Overrides Object.ToString().)
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  NameDescription
Explicit interface implemetationPrivate methodIDeserializationCallback.OnDeserializationRuns when the entire object graph has been deserialized.
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Conventions for comparing and sorting data vary from culture to culture. For example, sort order may be based on phonetics or on the visual representation of characters. In East Asian languages, characters are sorted by the stroke and radical of ideographs. Sorting also depends on the order languages and cultures use for the alphabet. For example, the Danish language has an "Æ" character that it sorts after "Z" in the alphabet. In addition, comparisons may be case-sensitive or case-insensitive, and casing rules may also differ by culture. The CompareInfo class is responsible for maintaining this culture-sensitive string comparison data and for performing culture-sensitive string operations.

Typically, you do not have to instantiate a CompareInfo object directly, because one is used implicitly by all non-ordinal string comparison operations, including calls to the String.Compare method. However, if you do want to retrieve a CompareInfo object, you can do it in one of these ways:

  • By retrieving the value of the CultureInfo.CompareInfo property for a particular culture.

  • By calling the static GetCompareInfo method with a culture name. This allows for late-bound access to a CompareInfo object.

Ignored search values

Character sets include ignorable characters, which are characters that are not considered when performing a linguistic or culture-sensitive comparison. Comparison methods such as IndexOf and LastIndexOf do not consider such characters when they perform a culture-sensitive comparison. Ignorable characters include:

  • String.Empty. Culture-sensitive comparison methods will always find an empty string at the beginning (index zero) of the string being searched.

  • A character or string consisting of characters with code points that are not considered in the operation because of comparison options, In particular, the CompareOptions.IgnoreNonSpace and CompareOptions.IgnoreSymbols options produce searches in which symbols and nonspacing combining characters are ignored.

  • A string with code points that have no linguistic significance. For example, a soft hyphen (U+00AD) is always ignored in a culture-sensitive string comparison.

Security considerations

If a security decision depends on a string comparison or a case change, you should use the InvariantCulture property to ensure that the behavior is consistent, regardless of the culture settings of the operating system.

NoteNote

When possible, you should use string comparison methods that have a parameter of type CompareOptions to specify the kind of comparison expected. As a general rule, use linguistic options (using the current culture) for comparing strings displayed in the user interface and specify Ordinal or OrdinalIgnoreCase for security comparisons.

The following example shows how the CompareInfo object associated with a CultureInfo object affects string comparison.

using System;
using System.Text;
using System.Globalization;

public sealed class App
{
    static void Main(string[] args)
    {
        String[] sign = new String[] { "<", "=", ">" };

        // The code below demonstrates how strings compare  
        // differently for different cultures.
        String s1 = "Coté", s2 = "coté", s3 = "côte";

        // Set sort order of strings for French in France.
        CompareInfo ci = new CultureInfo("fr-FR").CompareInfo;
        Console.WriteLine("The LCID for {0} is {1}.", ci.Name, ci.LCID);

        // Display the result using fr-FR Compare of Coté = coté.  	
        Console.WriteLine("fr-FR Compare: {0} {2} {1}",
            s1, s2, sign[ci.Compare(s1, s2, CompareOptions.IgnoreCase) + 1]);

        // Display the result using fr-FR Compare of coté > côte.
        Console.WriteLine("fr-FR Compare: {0} {2} {1}",
            s2, s3, sign[ci.Compare(s2, s3, CompareOptions.None) + 1]);

        // Set sort order of strings for Japanese as spoken in Japan.
        ci = new CultureInfo("ja-JP").CompareInfo;
        Console.WriteLine("The LCID for {0} is {1}.", ci.Name, ci.LCID);

        // Display the result using ja-JP Compare of coté < côte. 
        Console.WriteLine("ja-JP Compare: {0} {2} {1}",
            s2, s3, sign[ci.Compare(s2, s3) + 1]);
    }
}

// This code produces the following output. 
//  
// The LCID for fr-FR is 1036. 
// fr-FR Compare: Coté = coté 
// fr-FR Compare: coté > côte 
// The LCID for ja-JP is 1041. 
// ja-JP Compare: coté < côte

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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