Aggregation
Aggregate, Average, Count, LongCount, Max, Min, Sum
Conversion
AsEnumerable, Cast, OfType, ToArray, ToDictionary, ToList, ToLookup
Element
ElementAt, ElementAtOrDefault, First, FirstOrDefault, Last, LastOrDefault, Single, SingleOrDefault
ElementAt
ElementAtOrDefault
First (simple)
First (conditional)
FirstOrDefault
Last
LastOrDefault (simple)
LastOrDefault (conditional)
Single
SingleOrDefault
Generation
DefaultIfEmpty, Empty, Range, Repeat
Grouping
GroupBy
Join
GroupJoin, Join
Ordering
OrderBy, OrderByDescending, Reverse, ThenBy, ThenByDescending
OrderBy (simple - numbers)
OrderBy (simple - dates)
OrderBy (simple - objects)
OrderByDescending
Reverse
ThenBy
ThenByDescending
Other
Concat, SequenceEqual, Zip
Partitioning
Skip, SkipWhile, Take, TakeWhile
Projection
Select, SelectMany
Quantifiers
All, Any, Contains
Restriction
Where
Set
Distinct, Except, Intersect, Union
Close
Empty: Generates an empty collection (with no elements).
Empty: Generates an empty collection (with no elements). |
Empty: Generates an empty collection (with no elements). |
This Query Expression sample creates an empty sequence of type string. |
This Query Expression sample creates an empty sequence of type string. |
// A Query Expression cannot be constructed for Empty() with index in C#. // Consider using a Lambda Expression instead.
' A Query Expression cannot be constructed for Empty() with index in VB.NET. ' Consider using a Lambda Expression instead.
// A Query Expression cannot be constructed for Empty() with index in F#. // Consider using a Lambda Expression instead.
static void Sample_Empty_Lambda() { var empty = Enumerable.Empty<string>(); // To make sequence into an array use empty.ToArray() Debug.WriteLine("Sequence is empty:"); Debug.WriteLine(empty.Count() == 0); }Output:
Sequence is empty: True
Private Shared Sub Sample_Empty_Lambda() Dim empty = Enumerable.Empty(Of String)() ' To make sequence into an array use empty.ToArray() Debug.WriteLine("Sequence is empty:") Debug.WriteLine(empty.Count() = 0) End SubOutput:
Sequence is empty: True
let Sample_Empty_Lambda() = let empty = Enumerable.Empty<string>() // To make sequence into an array use empty.ToArray() Debug.WriteLine(sprintf "Sequence is empty:") Debug.WriteLine(sprintf "%b" (empty.Count() = 0))Output:
Sequence is empty: true