When this object is passed to a Hashtable constructor, it overrides the GetHashCode( ) method to allow string comparison without regard to case. If you pass an instance of this type into the Hashtable constructor, you should also pass in an instance of CaseInsensitiveComparer to ensure that any comparison operations (such as sorting) are also performed in a case-insensitive fashion. You can obtain a standard provider that uses the System.Globalization.InvariantCulture rules for generating hashcodes by using the CaseInsensitiveComparer instance returned from the static DefaultInvariant property.

public class CaseInsensitiveHashCodeProvider : IHashCodeProvider {
// Public Constructors
   public CaseInsensitiveHashCodeProvider( );
   public CaseInsensitiveHashCodeProvider(System.Globalization.CultureInfo culture);
// Public Static Properties
   public static CaseInsensitiveHashCodeProvider Default{get; }
   public static CaseInsensitiveHashCodeProvider DefaultInvariant{get; }
// Public Instance Methods
   public int GetHashCode(object obj);  
// implements IHashCodeProvider
}