Provides a base class for implementations of the IComparer(T) generic interface.
Assembly: mscorlib (in mscorlib.dll)
Thetype exposes the following members.
|Compare||When overridden in a derived class, performs a comparison of two objects of the same type and returns a value indicating whether one object is less than, equal to, or greater than the other.|
|Create||Creates a comparer by using the specified comparison.|
|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 the default hash function. (Inherited from Object.)|
|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.)|
Derive from this class to provide a custom implementation of the IComparer(T) interface for use with collection classes such as the SortedList(TKey, TValue) and SortedDictionary(TKey, TValue) generic classes.
The difference between deriving from the class and implementing the System.IComparable interface is as follows:
To specify how two objects should be compared by default, implement the System.IComparable interface in your class. This ensures that sort operations will use the default comparison code that you provided.
To define a comparer to use instead of the default comparer, derive from the class. You can then use this comparer in sort operations that take a comparer as a parameter.
The object returned by the Default property uses the System.IComparable(T) generic interface (IComparable<T> in C#, IComparable(Of T) in Visual Basic) to compare two objects. If type T does not implement the System.IComparable(T) generic interface, the Default property returns a that uses the System.IComparable interface.Notes to Implementers
For string comparisons, the StringComparer class is recommended over Comparer<String>. Properties of the StringComparer class return predefined instances that perform string comparisons with different combinations of culture-sensitivity and case-sensitivity. The case-sensitivity and culture-sensitivity are consistent among the members of the same StringComparer instance.
For more information on culture-specific comparisons, see the System.Globalization namespace and Globalizing and Localizing .NET Framework Applications.
The following example derives a class, BoxLengthFirst, from the class. This comparer compares two objects of type Box. It sorts them first by length, then by height, and then by width. The Box class implements the IComparable(T) interface to control the default comparison between two Box objects. This default implementation sorts first by height, then by length, and then by width. The example shows the differences between the two comparisons by sorting a list of Box objects first by using the BoxLengthFirst comparer and then by using the default comparer.