Enumerable.OrderBy Method

Source:

OrderBy.cs

Source:

OrderBy.cs

Source:

OrderBy.cs

Source:

OrderBy.cs

Source:

OrderBy.cs

public:
generic 
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IOrderedEnumerable ^ OrderBy(System::Collections::Generic::IEnumerable ^ source, Func ^ keySelector);

public static System.Linq.IOrderedEnumerable OrderBy(this System.Collections.Generic.IEnumerable source, Func keySelector);

static member OrderBy : seq<'Source> * Func<'Source, 'Key> -> System.Linq.IOrderedEnumerable<'Source>

Public Function OrderBy(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey)) As IOrderedEnumerable(Of TSource)

Type Parameters

Parameters

Returns

An IOrderedEnumerable whose elements are sorted according to a key.

Exceptions

Examples

The following code example demonstrates how to use OrderBy(IEnumerable, Func) to sort the elements of a sequence.

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
}

public static void OrderByEx1()
{
    Pet[] pets = { new Pet { Name="Barley", Age=8 },
                   new Pet { Name="Boots", Age=4 },
                   new Pet { Name="Whiskers", Age=1 } };

    IEnumerable query = pets.OrderBy(pet => pet.Age);

    foreach (Pet pet in query)
    {
        Console.WriteLine("{0} - {1}", pet.Name, pet.Age);
    }
}

/*
 This code produces the following output:

 Whiskers - 1
 Boots - 4
 Barley - 8
*/

Structure Pet
    Public Name As String
    Public Age As Integer
End Structure

Sub OrderByEx1()
    ' Create an array of Pet objects.
    Dim pets() As Pet = {New Pet With {.Name = "Barley", .Age = 8},
                     New Pet With {.Name = "Boots", .Age = 4},
                     New Pet With {.Name = "Whiskers", .Age = 1}}

    ' Order the Pet objects by their Age property.
    Dim query As IEnumerable(Of Pet) =
    pets.OrderBy(Function(pet) pet.Age)

    Dim output As New System.Text.StringBuilder
    For Each pt As Pet In query
        output.AppendLine(pt.Name & " - " & pt.Age)
    Next

    ' Display the output.
    Console.WriteLine(output.ToString())
End Sub

' This code produces the following output:
'
' Whiskers - 1
' Boots - 4
' Barley - 8

Remarks

This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in C# or For Each in Visual Basic.

To order a sequence by the values of the elements themselves, specify the identity function (x => x in C# or Function(x) x in Visual Basic) for keySelector.

Two methods are defined to extend the type IOrderedEnumerable, which is the return type of this method. These two methods, namely ThenBy and ThenByDescending, enable you to specify additional sort criteria to sort a sequence. ThenBy and ThenByDescending also return an IOrderedEnumerable, which means any number of consecutive calls to ThenBy or ThenByDescending can be made.

This method compares keys by using the default comparer Default.

This method performs a stable sort; that is, if the keys of two elements are equal, the order of the elements is preserved. In contrast, an unstable sort does not preserve the order of elements that have the same key.

In query expression syntax, an orderby (C#) or Order By (Visual Basic) clause translates to an invocation of OrderBy.

See also

• OrderByDescending(IEnumerable, Func)
• OrderByDescending(IEnumerable, Func, IComparer)
• orderby clause (C# Reference)
• Order By Clause (Visual Basic)

Source:

OrderBy.cs

Source:

OrderBy.cs

Source:

OrderBy.cs

Source:

OrderBy.cs

Source:

OrderBy.cs

public:
generic 
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IOrderedEnumerable ^ OrderBy(System::Collections::Generic::IEnumerable ^ source, Func ^ keySelector, System::Collections::Generic::IComparer ^ comparer);

public static System.Linq.IOrderedEnumerable OrderBy(this System.Collections.Generic.IEnumerable source, Func keySelector, System.Collections.Generic.IComparer comparer);

public static System.Linq.IOrderedEnumerable OrderBy(this System.Collections.Generic.IEnumerable source, Func keySelector, System.Collections.Generic.IComparer? comparer);

static member OrderBy : seq<'Source> * Func<'Source, 'Key> * System.Collections.Generic.IComparer<'Key> -> System.Linq.IOrderedEnumerable<'Source>

Public Function OrderBy(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), comparer As IComparer(Of TKey)) As IOrderedEnumerable(Of TSource)

Type Parameters

Parameters

Returns

An IOrderedEnumerable whose elements are sorted according to a key.

Exceptions

Remarks

This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in C# or For Each in Visual Basic.

To order a sequence by the values of the elements themselves, specify the identity function (x => x in C# or Function(x) x in Visual Basic) for keySelector.

Two methods are defined to extend the type IOrderedEnumerable, which is the return type of this method. These two methods, namely ThenBy and ThenByDescending, enable you to specify additional sort criteria to sort a sequence. ThenBy and ThenByDescending also return an IOrderedEnumerable, which means any number of consecutive calls to ThenBy or ThenByDescending can be made.

If comparer is null, the default comparer Default is used to compare keys.

This method performs a stable sort; that is, if the keys of two elements are equal, the order of the elements is preserved. In contrast, an unstable sort does not preserve the order of elements that have the same key.

See also

• OrderByDescending(IEnumerable, Func)
• OrderByDescending(IEnumerable, Func, IComparer)