Enumerable.LongCount Metoda
Definicja
Przeciążenia
| LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
Zwraca element Int64 reprezentujący liczbę elementów w sekwencji spełnia warunek.Returns an Int64 that represents how many elements in a sequence satisfy a condition. |
| LongCount<TSource>(IEnumerable<TSource>) |
Zwraca wartość Int64 reprezentującą łączną liczbę elementów w sekwencji.Returns an Int64 that represents the total number of elements in a sequence. |
LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static long LongCount(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, bool> ^ predicate);public static long LongCount<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,bool> predicate);static member LongCount : seq<'Source> * Func<'Source, bool> -> int64<Extension()>
Public Function LongCount(Of TSource) (source As IEnumerable(Of TSource), predicate As Func(Of TSource, Boolean)) As LongParametry typu
- TSource
Typ elementów source .The type of the elements of source.
Parametry
- source
- IEnumerable<TSource>
Element IEnumerable<T> zawierający elementy do zliczenia.An IEnumerable<T> that contains the elements to be counted.
Funkcja testowania każdego elementu na stanie.A function to test each element for a condition.
Zwraca
Liczba, która reprezentuje, ile elementów w sekwencji spełnia warunek w funkcji predykatu.A number that represents how many elements in the sequence satisfy the condition in the predicate function.
Wyjątki
source lub predicate jest null .source or predicate is null.
Przykłady
Poniższy przykład kodu demonstruje, jak używać LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) do zliczania elementów w tablicy, które spełniają warunek.The following code example demonstrates how to use LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) to count the elements in an array that satisfy a condition.
class Pet
{
public string Name { get; set; }
public int Age { get; set; }
}
public static void LongCountEx2()
{
Pet[] pets = { new Pet { Name="Barley", Age=8 },
new Pet { Name="Boots", Age=4 },
new Pet { Name="Whiskers", Age=1 } };
const int Age = 3;
long count = pets.LongCount(pet => pet.Age > Age);
Console.WriteLine("There are {0} animals over age {1}.", count, Age);
}
/*
This code produces the following output:
There are 2 animals over age 3.
*/
Structure Pet
Public Name As String
Public Age As Integer
End Structure
Sub LongCountEx2()
' Create a list of Pet objects.
Dim pets As New List(Of Pet)(New Pet() _
{New Pet With {.Name = "Barley", .Age = 8},
New Pet With {.Name = "Boots", .Age = 4},
New Pet With {.Name = "Whiskers", .Age = 1}})
' Determine the number of elements in the list
' where the pet's age is greater than a constant value (3).
Const Age As Integer = 3
Dim count As Long =
pets.LongCount(Function(pet) pet.Age > Age)
' Display the result.
Console.WriteLine($"There are {count} animals over age {Age}")
End Sub
' This code produces the following output:
'
' There are 2 animals over age 3
Uwagi
Użyj tej metody zamiast Count oczekiwać, że wynik będzie większy niż MaxValue .Use this method rather than Count when you expect the result to be greater than MaxValue.
W Visual Basic składni wyrażenia zapytania, Aggregate Into LongCount() klauzula tłumaczy na wywołanie LongCount .In Visual Basic query expression syntax, an Aggregate Into LongCount() clause translates to an invocation of LongCount.
Dotyczy
LongCount<TSource>(IEnumerable<TSource>)
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static long LongCount(System::Collections::Generic::IEnumerable<TSource> ^ source);public static long LongCount<TSource> (this System.Collections.Generic.IEnumerable<TSource> source);static member LongCount : seq<'Source> -> int64<Extension()>
Public Function LongCount(Of TSource) (source As IEnumerable(Of TSource)) As LongParametry typu
- TSource
Typ elementów source .The type of the elements of source.
Parametry
- source
- IEnumerable<TSource>
Element IEnumerable<T> zawierający elementy do zliczenia.An IEnumerable<T> that contains the elements to be counted.
Zwraca
Liczba elementów w sekwencji źródłowej.The number of elements in the source sequence.
Wyjątki
source to null.source is null.
Przykłady
Poniższy przykład kodu demonstruje, jak używać LongCount<TSource>(IEnumerable<TSource>) do zliczania elementów w tablicy.The following code example demonstrates how to use LongCount<TSource>(IEnumerable<TSource>) to count the elements in an array.
string[] fruits = { "apple", "banana", "mango",
"orange", "passionfruit", "grape" };
long count = fruits.LongCount();
Console.WriteLine("There are {0} fruits in the collection.", count);
/*
This code produces the following output:
There are 6 fruits in the collection.
*/
' Create an array of strings.
Dim fruits() As String =
{"apple", "banana", "mango", "orange", "passionfruit", "grape"}
' Get the number of items in the array.
Dim count As Long = fruits.LongCount()
' Display the result.
Console.WriteLine($"There are {count} fruits in the collection.")
' This code produces the following output:
'
' There are 6 fruits in the collection.
Uwagi
Użyj tej metody zamiast Count oczekiwać, że wynik będzie większy niż MaxValue .Use this method rather than Count when you expect the result to be greater than MaxValue.
W Visual Basic składni wyrażenia zapytania, Aggregate Into LongCount() klauzula tłumaczy na wywołanie LongCount .In Visual Basic query expression syntax, an Aggregate Into LongCount() clause translates to an invocation of LongCount.