Enumerable.LongCount Enumerable.LongCount Enumerable.LongCount Enumerable.LongCount Method

定義

傳回代表序列中項目數目的 Int64Returns an Int64 that represents the number of elements in a sequence.

多載

LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)

傳回 Int64,其代表序列中符合條件的項目數目。Returns an Int64 that represents how many elements in a sequence satisfy a condition.

LongCount<TSource>(IEnumerable<TSource>) LongCount<TSource>(IEnumerable<TSource>) LongCount<TSource>(IEnumerable<TSource>) LongCount<TSource>(IEnumerable<TSource>)

傳回代表序列中項目總數的 Int64Returns an Int64 that represents the total number of elements in a sequence.

LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)

傳回 Int64,其代表序列中符合條件的項目數目。Returns an Int64 that represents how many elements in a sequence satisfy a condition.

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 Long

類型參數

TSource

source 項目的類型。The type of the elements of source.

參數

source
IEnumerable<TSource>

包含要計算之項目的 IEnumerable<T>An IEnumerable<T> that contains the elements to be counted.

predicate
Func<TSource,Boolean>

用來測試每個項目是否符合條件的函式。A function to test each element for a condition.

傳回

數字,代表序列中符合述詞函式之條件的項目數目。A number that represents how many elements in the sequence satisfy the condition in the predicate function.

例外狀況

sourcepredicatenullsource or predicate is null.

符合的項目數目超出 MaxValueThe number of matching elements exceeds MaxValue.

範例

下列程式碼範例示範如何使用LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)來計算陣列中滿足條件的元素。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.
    MsgBox("There are " & count & " animals over age " & Age)
End Sub

' This code produces the following output:
'
' There are 2 animals over age 3

備註

Count當您預期結果MaxValue大於時, 請使用這個方法, 而不是。Use this method rather than Count when you expect the result to be greater than MaxValue.

在 Visual Basic 查詢運算式語法中, Aggregate Into LongCount()子句會轉譯成的LongCount調用。In Visual Basic query expression syntax, an Aggregate Into LongCount() clause translates to an invocation of LongCount.

另請參閱

LongCount<TSource>(IEnumerable<TSource>) LongCount<TSource>(IEnumerable<TSource>) LongCount<TSource>(IEnumerable<TSource>) LongCount<TSource>(IEnumerable<TSource>)

傳回代表序列中項目總數的 Int64Returns an Int64 that represents the total number of elements in a sequence.

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 Long

類型參數

TSource

source 項目的類型。The type of the elements of source.

參數

source
IEnumerable<TSource>

包含要計算之項目的 IEnumerable<T>An IEnumerable<T> that contains the elements to be counted.

傳回

來源序列中的項目數目。The number of elements in the source sequence.

例外狀況

項目數目超出 MaxValueThe number of elements exceeds MaxValue.

範例

下列程式碼範例示範如何使用LongCount<TSource>(IEnumerable<TSource>)來計算陣列中的元素。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.
MsgBox("There are " & count & " fruits in the collection.")

' This code produces the following output:
'
' There are 6 fruits in the collection.

備註

Count當您預期結果MaxValue大於時, 請使用這個方法, 而不是。Use this method rather than Count when you expect the result to be greater than MaxValue.

在 Visual Basic 查詢運算式語法中, Aggregate Into LongCount()子句會轉譯成的LongCount調用。In Visual Basic query expression syntax, an Aggregate Into LongCount() clause translates to an invocation of LongCount.

另請參閱

適用於