Enumerable.Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Metoda
Definice
Zřetězí dvě sekvence.Concatenates 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)
Parametry typu
- TSource
Typ prvků vstupních sekvencí.The type of the elements of the input sequences.
Parametry
- first
- IEnumerable<TSource>
První sekvence, která se má zřetězitThe first sequence to concatenate.
- second
- IEnumerable<TSource>
Sekvence, která se má zřetězit k první sekvenci.The sequence to concatenate to the first sequence.
Návraty
- IEnumerable<TSource>
Obsahující IEnumerable<T> zřetězené prvky dvou vstupních sekvencí.An IEnumerable<T> that contains the concatenated elements of the two input sequences.
Výjimky
first
nebo second
je null
.first
or second
is null
.
Příklady
Následující příklad kódu ukazuje, jak použít Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) ke zřetězení dvou sekvencí.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
Alternativním způsobem zřetězení dvou sekvencí je vytvořit kolekci, například pole, sekvence a pak použít SelectMany metodu a předat jí funkci selektor identity.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. Následující příklad ukazuje toto použití 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
Poznámky
Tato metoda je implementována pomocí odloženého provedení.This method is implemented by using deferred execution. Okamžitá návratová hodnota je objekt, který ukládá všechny informace, které jsou požadovány k provedení této akce.The immediate return value is an object that stores all the information that is required to perform the action. Dotaz reprezentovaný touto metodou není proveden, dokud se nevytvoří výčet objektu buď voláním GetEnumerator
metody přímo nebo pomocí foreach
jazyka Visual C# nebo For Each
Visual Basic.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.
Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)Metoda se liší od metody, Union protože Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Metoda vrátí všechny původní prvky ve vstupních sekvencích.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. UnionMetoda vrátí pouze jedinečné prvky.The Union method returns only unique elements.