LINQSamples.com
  • Samples
  • Tutorials
  • About
  • Links
  • Contact
LINQ to Objects

Aggregation

Aggregate, Average, Count, LongCount, Max, Min, Sum

      Aggregate (simple)       Aggregate (seed)       Average       Count       LongCount       Max       Min       Sum

Conversion

AsEnumerable, Cast, OfType, ToArray, ToDictionary, ToList, ToLookup

      AsEnumerable       Cast       OfType       ToArray       ToDictionary (simple)       ToDictionary (conditional)       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

      DefaultIfEmpty (simple)       DefaultIfEmpty (default value)       Empty       Range       Repeat

Grouping

GroupBy

      GroupBy

Join

GroupJoin, Join

      GroupJoin (left outer join)       Join (inner join)

Ordering

OrderBy, OrderByDescending, Reverse, ThenBy, ThenByDescending

      OrderBy (simple - numbers)       OrderBy (simple - dates)       OrderBy (simple - objects)       OrderByDescending       Reverse       ThenBy       ThenByDescending

Other

Concat, SequenceEqual, Zip

      Concat (simple - numbers)       Concat (simple - strings)       SequenceEqual       Zip

Partitioning

Skip, SkipWhile, Take, TakeWhile

      Skip       SkipWhile       Take       TakeWhile

Projection

Select, SelectMany

      Select (simple)       Select (anonymous type)       Select (indexed)       SelectMany (cross join)

Quantifiers

All, Any, Contains

      All       Any       Contains

Restriction

Where

      Where (simple - numbers)       Where (simple - objects)       Where (indexed)

Set

Distinct, Except, Intersect, Union

      Distinct       Except       Intersect       Union
  Close

First (simple)

Lambda Query

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.

  • C#
  • VB.Net
  • F#
// 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
  • C#
  • VB.Net
  • F#
// 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

Share this sample on:

© 2023 - LINQSamples.com | Terms Of Service  -  Privacy Policy