Enumerable.OrderBy Method
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Sorts the elements of a sequence in ascending order.
OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) |
Sorts the elements of a sequence in ascending order according to a key. |
OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>) |
Sorts the elements of a sequence in ascending order by using a specified comparer. |
- Source:
- OrderBy.cs
- Source:
- OrderBy.cs
- Source:
- OrderBy.cs
Sorts the elements of a sequence in ascending order according to a key.
public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
static System::Linq::IOrderedEnumerable<TSource> ^ OrderBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector);
public static System.Linq.IOrderedEnumerable<TSource> OrderBy<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector);
static member OrderBy : seq<'Source> * Func<'Source, 'Key> -> System.Linq.IOrderedEnumerable<'Source>
<Extension()>
Public Function OrderBy(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey)) As IOrderedEnumerable(Of TSource)
Type Parameters
- TSource
The type of the elements of source
.
- TKey
The type of the key returned by keySelector
.
Parameters
- source
- IEnumerable<TSource>
A sequence of values to order.
- keySelector
- Func<TSource,TKey>
A function to extract a key from an element.
Returns
An IOrderedEnumerable<TElement> whose elements are sorted according to a key.
Exceptions
source
or keySelector
is null
.
Examples
The following code example demonstrates how to use OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) 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<Pet> 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<TElement>, 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<TElement>, which means any number of consecutive calls to ThenBy
or ThenByDescending
can be made.
Note
Because IOrderedEnumerable<TElement> inherits from IEnumerable<T>, you can call OrderBy or OrderByDescending on the results of a call to OrderBy, OrderByDescending, ThenBy or ThenByDescending. Doing this introduces a new primary ordering that ignores the previously established ordering.
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<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)
- OrderByDescending<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)
- orderby clause (C# Reference)
- Order By Clause (Visual Basic)
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
- Source:
- OrderBy.cs
- Source:
- OrderBy.cs
- Source:
- OrderBy.cs
Sorts the elements of a sequence in ascending order by using a specified comparer.
public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
static System::Linq::IOrderedEnumerable<TSource> ^ OrderBy(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, System::Collections::Generic::IComparer<TKey> ^ comparer);
public static System.Linq.IOrderedEnumerable<TSource> OrderBy<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, System.Collections.Generic.IComparer<TKey> comparer);
public static System.Linq.IOrderedEnumerable<TSource> OrderBy<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, System.Collections.Generic.IComparer<TKey>? comparer);
static member OrderBy : seq<'Source> * Func<'Source, 'Key> * System.Collections.Generic.IComparer<'Key> -> System.Linq.IOrderedEnumerable<'Source>
<Extension()>
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
- TSource
The type of the elements of source
.
- TKey
The type of the key returned by keySelector
.
Parameters
- source
- IEnumerable<TSource>
A sequence of values to order.
- keySelector
- Func<TSource,TKey>
A function to extract a key from an element.
- comparer
- IComparer<TKey>
An IComparer<T> to compare keys.
Returns
An IOrderedEnumerable<TElement> whose elements are sorted according to a key.
Exceptions
source
or keySelector
is null
.
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<TElement>, 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<TElement>, which means any number of consecutive calls to ThenBy
or ThenByDescending
can be made.
Note
Because IOrderedEnumerable<TElement> inherits from IEnumerable<T>, you can call OrderBy or OrderByDescending on the results of a call to OrderBy, OrderByDescending, ThenBy or ThenByDescending. Doing this introduces a new primary ordering that ignores the previously established ordering.
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<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)
- OrderByDescending<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
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