Queryable.LongCount<'TSource> Method (IQueryable<'TSource>, Expression<Func<'TSource, Boolean>>)
Returns an Int64 that represents the number of elements in a sequence that satisfy a condition.
Assembly: System.Core (in System.Core.dll)
static member LongCount<'TSource> : source:IQueryable<'TSource> * predicate:Expression<Func<'TSource, bool>> -> int64
An IQueryable<'T> that contains the elements to be counted.
Return ValueType: System.Int64
The number of elements in source that satisfy the condition in the predicate function.
The type of the elements of source.
This method has at least one parameter of type Expression<'TDelegate> whose type argument is one of the Func<'T, 'TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<'TDelegate>.
The 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.method generates a
The query behavior that occurs as a result of executing an expression tree that represents calling Int64.depends on the implementation of the type of the source parameter. The expected behavior is that it counts the number of items in source that satisfy the condition specified by predicate and returns an
Available since 8
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Available since 8.1