IOrderedEnumerable<TElement>.CreateOrderedEnumerable<TKey> Method

Definition

Namespace:

System.Linq

Assembly:

System.Linq.dll

Performs a subsequent ordering on the elements of an IOrderedEnumerable<TElement> according to a key.

public:
generic <typename TKey>
 System::Linq::IOrderedEnumerable<TElement> ^ CreateOrderedEnumerable(Func<TElement, TKey> ^ keySelector, System::Collections::Generic::IComparer<TKey> ^ comparer, bool descending);

public System.Linq.IOrderedEnumerable<out TElement> CreateOrderedEnumerable<TKey> (Func<out TElement,TKey> keySelector, System.Collections.Generic.IComparer<TKey>? comparer, bool descending);

abstract member CreateOrderedEnumerable : Func<'Element, 'Key> * System.Collections.Generic.IComparer<'Key> * bool -> System.Linq.IOrderedEnumerable<'Element>

Public Function CreateOrderedEnumerable(Of TKey) (keySelector As Func(Of Out TElement, TKey), comparer As IComparer(Of TKey), descending As Boolean) As IOrderedEnumerable(Of Out TElement)

Type Parameters

TKey

The type of the key produced by keySelector.

Parameters

keySelector

Func<TElement,TKey>

The Func<T,TResult> used to extract the key for each element.

comparer

IComparer<TKey>

The IComparer<T> used to compare keys for placement in the returned sequence.

descending

Boolean

true to sort the elements in descending order; false to sort the elements in ascending order.

Returns

IOrderedEnumerable<TElement>

An IOrderedEnumerable<TElement> whose elements are sorted according to a key.

Examples

The following code example demonstrates how to use CreateOrderedEnumerable to perform a secondary ordering on an IOrderedEnumerable<TElement>.

// Create an array of strings to sort.
string[] fruits = { "apricot", "orange", "banana", "mango", "apple", "grape", "strawberry" };
// First sort the strings by their length.
IOrderedEnumerable<string> sortedFruits2 =
    fruits.OrderBy(fruit => fruit.Length);
// Secondarily sort the strings alphabetically, using the default comparer.
IOrderedEnumerable<string> sortedFruits3 =
    sortedFruits2.CreateOrderedEnumerable<string>(
        fruit => fruit,
        Comparer<string>.Default, false);

// Output the resulting sequence of strings.
foreach (string fruit in sortedFruits3)
    Console.WriteLine(fruit);

// This code produces the following output:
//
// apple
// grape
// mango
// banana
// orange
// apricot
// strawberry

' Create an array of strings to sort.
Dim fruits() As String = {"apricot", "orange", "banana", "mango", "apple", "grape", "strawberry"}
' First sort the strings by their length.
Dim sortedFruits2 As IOrderedEnumerable(Of String) = _
    fruits.OrderBy(Function(ByVal fruit) fruit.Length)
' Secondarily sort the strings alphabetically, using the default comparer.
Dim sortedFruits3 As IOrderedEnumerable(Of String) = _
    sortedFruits2.CreateOrderedEnumerable(Of String)( _
        Function(ByVal fruit) fruit, _
        System.Collections.Generic.Comparer(Of String).Default, _
        False)

Dim output As New System.Text.StringBuilder
' Output the resulting sequence of strings.
For Each fruit As String In sortedFruits3
    output.AppendLine(fruit)
Next

' Display the results.
MsgBox(output.ToString())

' This code produces the following output:
'
' apple
' grape
' mango
' banana
' orange
' apricot
' strawberry

Remarks

The functionality provided by this method is like that provided by ThenBy or ThenByDescending, depending on whether descending is true or false. They both perform a subordinate ordering of an already sorted sequence of type IOrderedEnumerable<TElement>.