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
First: Retrieves first element from a collection. Throws exception if collection is empty.
| First: Retrieves first element from a collection. Throws exception if collection is empty. |
| First: Retrieves first element from a collection. Throws exception if collection is empty. |
| This Lambda Expression sample retrieves first element from an array. |
| This Lambda Expression sample retrieves first element from an array. |
// A Query Expression cannot be constructed for First() in C#. // Consider using a Lambda Expression instead.
' A Query Expression cannot be constructed for First() in VB.NET. ' Consider using a Lambda Expression instead.
// There is no First() for Query Expressions in F#, but it has the similar "head".
let Sample_First_Linq_Simple() =
let fruits = [|"Banana"; "Apple"; "Orange"|]
let result = query {
for f in fruits do
head
}
Debug.WriteLine(sprintf "First element in the array is:")
Debug.WriteLine(sprintf "%s" result)
Output: First element in the array is: Banana
// Note: Operator First will throw an exception, if there is not at least one element in the sequence.
static void Sample_First_Lambda_Simple()
{
string[] fruits = { "Banana", "Apple", "Orange" };
var result = fruits.First();
Debug.WriteLine("First element in the array is:");
Debug.WriteLine(result);
}
Output: First element in the array is: Banana
' Note: First will throw an exception if there is not at least one element in the sequence.
Private Shared Sub Sample_First_Lambda_Simple()
Dim fruits As String() = {"Banana", "Apple", "Orange"}
Dim result = fruits.First()
Debug.WriteLine("First element in the array is:")
Debug.WriteLine(result)
End Sub
Output: First element in the array is: Banana
let Sample_First_Lambda_Simple() =
let fruits = [|"Banana"; "Apple"; "Orange"|]
let result = fruits.First()
Debug.WriteLine(sprintf "First element in the array is:")
Debug.WriteLine(sprintf "%s" result)
Output: First element in the array is: Banana