Queryable.LongCount<TSource> Method (IQueryable<TSource>)
Returns an Int64 that represents the total number of elements in a sequence.
Assembly: System.Core (in System.Core.dll)
The type of the elements of source.
Return ValueType: System.Int64
The number of elements in source.
Usage NoteIn Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<>. 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).
The method generates a MethodCallExpression that represents calling itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.
The query behavior that occurs as a result of executing an expression tree that represents calling depends on the implementation of the type of the source parameter. The expected behavior is that it counts the number of items in source and returns an Int64.
The following code example demonstrates how to use to count the elements in an array.
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.