CaseInsensitiveHashCodeProvider Class
Note: This API is now obsolete. The non-obsolete alternative is StringComparer.
Supplies a hash code for an object, using a hashing algorithm that ignores the case of strings.
Namespace: System.Collections
Assembly: mscorlib (in mscorlib.dll)
The CaseInsensitiveHashCodeProvider type exposes the following members.
| Name | Description | |
|---|---|---|
![]() ![]() | CaseInsensitiveHashCodeProvider() | Initializes a new instance of the CaseInsensitiveHashCodeProvider class using the Thread::CurrentCulture of the current thread. |
![]() ![]() | CaseInsensitiveHashCodeProvider(CultureInfo) | Initializes a new instance of the CaseInsensitiveHashCodeProvider class using the specified System.Globalization::CultureInfo. |
| Name | Description | |
|---|---|---|
![]() ![]() ![]() | Default | Gets an instance of CaseInsensitiveHashCodeProvider that is associated with the Thread::CurrentCulture of the current thread and that is always available. |
![]() ![]() ![]() | DefaultInvariant | Gets an instance of CaseInsensitiveHashCodeProvider that is associated with CultureInfo::InvariantCulture and that is always available. |
| Name | Description | |
|---|---|---|
![]() ![]() | Equals(Object) | Determines whether the specified object is equal to the current object. (Inherited from Object.) |
![]() ![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() ![]() | GetHashCode() | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() ![]() | GetHashCode(Object) | Returns a hash code for the given object, using a hashing algorithm that ignores the case of strings. |
![]() ![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() ![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() ![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
CaseInsensitiveHashCodeProvider implements the IHashCodeProvider interface supporting case-insensitive comparisons on strings, just as CaseInsensitiveComparer implements the IComparer interface supporting case-insensitive comparisons on strings.
The objects used as keys by a Hashtable are required to override the Object::GetHashCode method (or the IHashCodeProvider interface) and the Object::Equals method (or the IComparer interface). The implementation of both methods or interfaces must handle case sensitivity the same way; otherwise, the Hashtable might behave incorrectly. For example, when creating a Hashtable, you must use this class with the CaseInsensitiveComparer class or any case-insensitive IComparer implementation.
The following code example creates a case-sensitive hash table and a case-insensitive hash table and demonstrates the difference in their behavior, even if both contain the same elements.
using namespace System; using namespace System::Collections; using namespace System::Globalization; int main() { // Create a Hashtable using the default hash code provider and the default comparer. Hashtable^ myHT1 = gcnew Hashtable; myHT1->Add( "FIRST", "Hello" ); myHT1->Add( "SECOND", "World" ); myHT1->Add( "THIRD", "!" ); // Create a Hashtable using a case-insensitive code provider and a case-insensitive comparer, // based on the culture of the current thread. Hashtable^ myHT2 = gcnew Hashtable( gcnew CaseInsensitiveHashCodeProvider,gcnew CaseInsensitiveComparer ); myHT2->Add( "FIRST", "Hello" ); myHT2->Add( "SECOND", "World" ); myHT2->Add( "THIRD", "!" ); // Create a Hashtable using a case-insensitive code provider and a case-insensitive comparer, // based on the InvariantCulture. Hashtable^ myHT3 = gcnew Hashtable( CaseInsensitiveHashCodeProvider::DefaultInvariant,CaseInsensitiveComparer::DefaultInvariant ); myHT3->Add( "FIRST", "Hello" ); myHT3->Add( "SECOND", "World" ); myHT3->Add( "THIRD", "!" ); // Create a Hashtable using a case-insensitive code provider and a case-insensitive comparer, // based on the Turkish culture (tr-TR), where "I" is not the uppercase version of "i". CultureInfo^ myCul = gcnew CultureInfo( "tr-TR" ); Hashtable^ myHT4 = gcnew Hashtable( gcnew CaseInsensitiveHashCodeProvider( myCul ),gcnew CaseInsensitiveComparer( myCul ) ); myHT4->Add( "FIRST", "Hello" ); myHT4->Add( "SECOND", "World" ); myHT4->Add( "THIRD", "!" ); // Search for a key in each hashtable. Console::WriteLine( "first is in myHT1: {0}", myHT1->ContainsKey( "first" ) ); Console::WriteLine( "first is in myHT2: {0}", myHT2->ContainsKey( "first" ) ); Console::WriteLine( "first is in myHT3: {0}", myHT3->ContainsKey( "first" ) ); Console::WriteLine( "first is in myHT4: {0}", myHT4->ContainsKey( "first" ) ); } /* This code produces the following output. Results vary depending on the system's culture settings. first is in myHT1: False first is in myHT2: True first is in myHT3: True first is in myHT4: False */
.NET Framework
Supported in: 1.1, 1.0Obsolete (compiler warning) in 4.5
Obsolete (compiler warning) in 4
Obsolete (compiler warning) in 3.5
Obsolete (compiler warning) in 3.5 SP1
Obsolete (compiler warning) in 3.0
Obsolete (compiler warning) in 3.0 SP1
Obsolete (compiler warning) in 3.0 SP2
Obsolete (compiler warning) in 2.0
Obsolete (compiler warning) in 2.0 SP1
Obsolete (compiler warning) in 2.0 SP2
.NET Framework Client Profile
Obsolete (compiler warning) in 4Obsolete (compiler warning) in 3.5 SP1
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.
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