Enumerable.Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Methode
Definition
Verkettet zwei SequenzenConcatenates two sequences.
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::IEnumerable<TSource> ^ Concat(System::Collections::Generic::IEnumerable<TSource> ^ first, System::Collections::Generic::IEnumerable<TSource> ^ second);
public static System.Collections.Generic.IEnumerable<TSource> Concat<TSource> (this System.Collections.Generic.IEnumerable<TSource> first, System.Collections.Generic.IEnumerable<TSource> second);
static member Concat : seq<'Source> * seq<'Source> -> seq<'Source>
<Extension()>
Public Function Concat(Of TSource) (first As IEnumerable(Of TSource), second As IEnumerable(Of TSource)) As IEnumerable(Of TSource)
Typparameter
- TSource
Der Typ der Elemente der Eingabesequenzen.The type of the elements of the input sequences.
Parameter
- first
- IEnumerable<TSource>
Die erste zu verkettende Sequenz.The first sequence to concatenate.
- second
- IEnumerable<TSource>
Die Sequenz, die mit der ersten Sequenz verkettet werden soll.The sequence to concatenate to the first sequence.
Gibt zurück
- IEnumerable<TSource>
Ein IEnumerable<T>, das die verketteten Elemente der beiden Eingabesequenzen enthält.An IEnumerable<T> that contains the concatenated elements of the two input sequences.
Ausnahmen
first
oder second
ist null
.first
or second
is null
.
Beispiele
Im folgenden Codebeispiel wird veranschaulicht, wie verwendet wird, Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) um zwei Sequenzen zu verketten.The following code example demonstrates how to use Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) to concatenate two sequences.
class Pet
{
public string Name { get; set; }
public int Age { get; set; }
}
static Pet[] GetCats()
{
Pet[] cats = { new Pet { Name="Barley", Age=8 },
new Pet { Name="Boots", Age=4 },
new Pet { Name="Whiskers", Age=1 } };
return cats;
}
static Pet[] GetDogs()
{
Pet[] dogs = { new Pet { Name="Bounder", Age=3 },
new Pet { Name="Snoopy", Age=14 },
new Pet { Name="Fido", Age=9 } };
return dogs;
}
public static void ConcatEx1()
{
Pet[] cats = GetCats();
Pet[] dogs = GetDogs();
IEnumerable<string> query =
cats.Select(cat => cat.Name).Concat(dogs.Select(dog => dog.Name));
foreach (string name in query)
{
Console.WriteLine(name);
}
}
// This code produces the following output:
//
// Barley
// Boots
// Whiskers
// Bounder
// Snoopy
// Fido
Structure Pet
Public Name As String
Public Age As Integer
End Structure
' Returns an array of Pet objects.
Function GetCats() As Pet()
Dim cats() As Pet = {New Pet With {.Name = "Barley", .Age = 8},
New Pet With {.Name = "Boots", .Age = 4},
New Pet With {.Name = "Whiskers", .Age = 1}}
Return cats
End Function
' Returns an array of Pet objects.
Function GetDogs() As Pet()
Dim dogs() As Pet = {New Pet With {.Name = "Bounder", .Age = 3},
New Pet With {.Name = "Snoopy", .Age = 14},
New Pet With {.Name = "Fido", .Age = 9}}
Return dogs
End Function
Sub ConcatEx1()
' Create two arrays of Pet objects.
Dim cats() As Pet = GetCats()
Dim dogs() As Pet = GetDogs()
' Project the Name of each cat and concatenate
' the collection of cat name strings with a collection
' of dog name strings.
Dim query As IEnumerable(Of String) =
cats _
.Select(Function(cat) cat.Name) _
.Concat(dogs.Select(Function(dog) dog.Name))
Dim output As New System.Text.StringBuilder
For Each name As String In query
output.AppendLine(name)
Next
' Display the output.
Console.WriteLine(output.ToString())
End Sub
' This code produces the following output:
'
' Barley
' Boots
' Whiskers
' Bounder
' Snoopy
' Fido
Eine alternative Möglichkeit zum Verketten von zwei Sequenzen besteht darin, eine Auflistung zu erstellen, z. b. ein Array mit Sequenzen, und dann die-Methode anzuwenden und SelectMany ihr die Identitäts Auswahlfunktion zu übergeben.An alternative way of concatenating two sequences is to construct a collection, for example an array, of sequences and then apply the SelectMany method, passing it the identity selector function. Im folgenden Beispiel wird diese Verwendung von veranschaulicht SelectMany .The following example demonstrates this use of SelectMany.
Pet[] cats = GetCats();
Pet[] dogs = GetDogs();
IEnumerable<string> query =
new[] { cats.Select(cat => cat.Name), dogs.Select(dog => dog.Name) }
.SelectMany(name => name);
foreach (string name in query)
{
Console.WriteLine(name);
}
// This code produces the following output:
//
// Barley
// Boots
// Whiskers
// Bounder
// Snoopy
// Fido
' Create two arrays of Pet objects.
Dim cats() As Pet = GetCats()
Dim dogs() As Pet = GetDogs()
' Create an IEnumerable collection that contains two elements.
' Each element is an array of Pet objects.
Dim animals() As IEnumerable(Of Pet) = {cats, dogs}
Dim query As IEnumerable(Of String) =
(animals.SelectMany(Function(pets) _
pets.Select(Function(pet) pet.Name)))
Dim output As New System.Text.StringBuilder
For Each name As String In query
output.AppendLine(name)
Next
' Display the output.
Console.WriteLine(output.ToString())
' This code produces the following output:
'
' Barley
' Boots
' Whiskers
' Bounder
' Snoopy
' Fido
Hinweise
Diese Methode wird mithilfe von verzögerter Ausführung implementiert.This method is implemented by using deferred execution. Der unmittelbare Rückgabewert ist ein Objekt, das alle Informationen speichert, die zum Ausführen der Aktion erforderlich sind.The immediate return value is an object that stores all the information that is required to perform the action. Die durch diese Methode dargestellte Abfrage wird erst ausgeführt, wenn das Objekt durch Aufrufen der- GetEnumerator
Methode direkt oder mithilfe von foreach
in Visual c# oder in Visual Basic aufgezählt wird For Each
.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 Visual C# or For Each
in Visual Basic.
Die- Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Methode unterscheidet sich von der- Union Methode, da die- Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Methode alle ursprünglichen Elemente in den Eingabe Sequenzen zurückgibt.The Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) method differs from the Union method because the Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) method returns all the original elements in the input sequences. Die- Union Methode gibt nur eindeutige-Elemente zurück.The Union method returns only unique elements.