Enumerable.Distinct(TSource) Method (IEnumerable(TSource))
Returns distinct elements from a sequence by using the default equality comparer to compare values.
Assembly: System.Core (in System.Core.dll)
The type of the elements of source.
- Type: System.Collections.Generic.IEnumerable()
The sequence to remove duplicate elements from.
Return ValueType: System.Collections.Generic.IEnumerable()
An IEnumerable(T) that contains distinct elements from the source sequence.
Usage NoteIn Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(). When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
source is a null reference (Nothing in Visual Basic).
This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.
The method returns an unordered sequence that contains no duplicate values. It uses the default equality comparer, Default, to compare values.
In Visual Basic query expression syntax, a Distinct clause translates to an invocation of Distinct.
The default equality comparer, Default, is used to compare values of the types that implement the IEquatable(T) generic interface. To compare a custom data type, you must implement this interface and provide your own GetHashCode and Equals methods for the type.
The following code example demonstrates how to use to return distinct elements from a sequence of integers.
If you want to return distinct elements from sequences of objects of some custom data type, you have to implement the IEquatable(T) generic interface in the class. The following code example shows how to implement this interface in a custom data type and provide GetHashCode and Equals methods.
After you implement this interface, you can use a sequence of Product objects in the method, as shown in the following example.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.