CompareInfo Class

CompareInfo Class

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

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

System.Object
  System.Globalization.CompareInfo

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

public class CompareInfo

The CompareInfo type exposes the following members.

  NameDescription
Public propertyNameGets the name of the culture used for sorting operations by this CompareInfo object.
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  NameDescription
Public methodCompare(String, String)Compares two strings and returns an integer that indicates their relationship to one another in the sort order.
Public methodCompare(String, String, CompareOptions)Compares two strings using the specified CompareOptions value and returns an integer that indicates their relationship to one another in the sort order.
Public methodCompare(String, Int32, String, Int32)Compares the end section of a string with the end section of another string and returns an integer that indicates their relationship to one another in the sort order.
Public methodCompare(String, Int32, String, Int32, CompareOptions)Compares the end section of a string with the end section of another string using the specified CompareOptions value and returns an integer that indicates their relationship to one another in the sort order.
Public methodCompare(String, Int32, Int32, String, Int32, Int32)Compares a section of one string with a section of another string and returns an integer that indicates their relationship to one another in the sort order.
Public methodCompare(String, Int32, Int32, String, Int32, Int32, CompareOptions)Compares a section of one string with a section of another string using the specified CompareOptions value and returns an integer that indicates their relationship to one another in the sort order.
Public methodEqualsDetermines whether the specified object is equal to the current CompareInfo object. (Overrides Object.Equals(Object).)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodStatic memberGetCompareInfoInitializes a new CompareInfo object that is associated with the culture with the specified name.
Public methodGetHashCodeServes as a hash function for the current CompareInfo for hashing algorithms and data structures, such as a hash table. (Overrides Object.GetHashCode().)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIndexOf(String, Char)Searches for the specified character and returns the zero-based index of the first occurrence within the entire source string.
Public methodIndexOf(String, String)Searches for the specified substring and returns the zero-based index of the first occurrence within the entire source string.
Public methodIndexOf(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, 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, 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 methodIndexOf(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 methodIndexOf(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 methodIndexOf(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 methodIndexOf(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 methodIndexOf(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 methodIsPrefix(String, String)Determines whether the specified source string starts with the specified prefix.
Public methodIsPrefix(String, String, CompareOptions)Determines whether the specified source string starts with the specified prefix using the specified CompareOptions value.
Public methodIsSuffix(String, String)Determines whether the specified source string ends with the specified suffix.
Public methodIsSuffix(String, String, CompareOptions)Determines whether the specified source string ends with the specified suffix using the specified CompareOptions value.
Public methodLastIndexOf(String, Char)Searches for the specified character and returns the zero-based index of the last occurrence within the entire source string.
Public methodLastIndexOf(String, String)Searches for the specified substring and returns the zero-based index of the last occurrence within the entire source string.
Public methodLastIndexOf(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, 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, 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 methodLastIndexOf(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 methodLastIndexOf(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 methodLastIndexOf(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 methodLastIndexOf(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 methodLastIndexOf(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 methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current CompareInfo. (Overrides Object.ToString().)
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The CultureInfo class includes a CompareInfo property that returns an instance of this class. Some string comparison methods, such as String.Compare, use the information in a CultureInfo.CompareInfo object to compare strings.

The CompareInfo class provides the GetCompareInfo method, instead of public constructors, to allow for late-bound access.

To create a CompareInfo object for any culture, the application should use the CultureInfo.CompareInfo property, or use the CompareInfo.GetCompareInfo method and provide the name of the culture whose CompareInfo object is to be returned.

Ignored Search Values

Comparison operations, such as those performed by the IndexOf or LastIndexOf methods, can yield unexpected results if the value to search for is ignored. The search value is ignored under the following conditions:

  • It is an empty string ("").

  • It consists of characters whose code points are not considered in the operation because of comparison options. For example, this occurs if the search string includes symbols and the value passed to a parameter of type CompareOptions includes the CompareOptions.IgnoreSymbols flag.

  • It consists of characters whose code points have no linguistic significance.

If the search value for the IndexOf method is an empty string, for example, the return value is zero.

Security Considerations

If a security decision depends on a string comparison, the application should test for equality using ordinal comparison. It should not use the Compare method.

Version Notes

Windows Phone

String comparison operations for strings containing trigraphs may not work as expected for cultures where trigraphs are used, such as "dzh" in the culture hu-HU. For example, IndexOf(String, String, CompareOptions) and IsSuffix(String, String, CompareOptions) may return an incorrect result.

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 Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      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;

      // Display the result using fr-FR Compare of Coté = coté.  	
      outputBlock.Text += String.Format("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.
      outputBlock.Text += String.Format("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;

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

// This code produces the following output.
// 
// fr-FR Compare: Coté = coté
// fr-FR Compare: coté > côte
// ja-JP Compare: coté < côte


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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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