Queryable.Count 메서드

정의

시퀀스의 요소 수를 반환합니다.Returns the number of elements in a sequence.

오버로드

Count<TSource>(IQueryable<TSource>)

시퀀스의 요소 수를 반환합니다.Returns the number of elements in a sequence.

Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)

지정된 시퀀스에서 특정 조건에 맞는 요소 수를 반환합니다.Returns the number of elements in the specified sequence that satisfies a condition.

Count<TSource>(IQueryable<TSource>)

시퀀스의 요소 수를 반환합니다.Returns the number of elements in a sequence.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static int Count(System::Linq::IQueryable<TSource> ^ source);
public static int Count<TSource> (this System.Linq.IQueryable<TSource> source);
static member Count : System.Linq.IQueryable<'Source> -> int
<Extension()>
Public Function Count(Of TSource) (source As IQueryable(Of TSource)) As Integer

형식 매개 변수

TSource

source 요소의 형식입니다.The type of the elements of source.

매개 변수

source
IQueryable<TSource>

개수를 셀 요소가 들어 있는 IQueryable<T>입니다.The IQueryable<T> that contains the elements to be counted.

반환

Int32

입력 시퀀스의 요소 수입니다.The number of elements in the input sequence.

예외

source이(가) null인 경우source is null.

source의 요소 수가 MaxValue보다 큰 경우The number of elements in source is larger than MaxValue.

예제

다음 코드 예제에서는를 사용 하 여 시퀀스에서 요소를 계산 하는 방법을 보여 줍니다 Count<TSource>(IQueryable<TSource>) .The following code example demonstrates how to use Count<TSource>(IQueryable<TSource>) to count the elements in a sequence.

string[] fruits = { "apple", "banana", "mango",
                    "orange", "passionfruit", "grape" };

int numberOfFruits = fruits.AsQueryable().Count();

Console.WriteLine(
    "There are {0} items in the array.",
    numberOfFruits);

// This code produces the following output:
//
// There are 6 items in the array.

Dim fruits() As String = {"apple", "banana", "mango", _
                    "orange", "passionfruit", "grape"}

Dim numberOfFruits As Integer = fruits.AsQueryable().Count()

MsgBox(String.Format( _
    "There are {0} items in the array.", _
    numberOfFruits))

' This code produces the following output:
'
' There are 6 items in the array. 

설명

Count<TSource>(IQueryable<TSource>)메서드는 자신을 MethodCallExpression 생성 된 제네릭 메서드로 호출 하는을 생성 합니다 Count<TSource>(IQueryable<TSource>) .The Count<TSource>(IQueryable<TSource>) method generates a MethodCallExpression that represents calling Count<TSource>(IQueryable<TSource>) itself as a constructed generic method. 그런 다음 MethodCallExpression Execute<TResult>(Expression) IQueryProvider Provider 매개 변수의 속성이 나타내는의 메서드에를 전달 합니다 source .It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

호출을 나타내는 식 트리를 실행 한 결과로 발생 하는 쿼리 동작은 Count<TSource>(IQueryable<TSource>) 매개 변수의 형식 구현에 따라 달라 집니다 source .The query behavior that occurs as a result of executing an expression tree that represents calling Count<TSource>(IQueryable<TSource>) depends on the implementation of the type of the source parameter. 예상 되는 동작은의 항목 수를 계산 하는 것입니다 source .The expected behavior is that it counts the number of items in source.

적용 대상

Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)

지정된 시퀀스에서 특정 조건에 맞는 요소 수를 반환합니다.Returns the number of elements in the specified sequence that satisfies a condition.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static int Count(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, bool> ^> ^ predicate);
public static int Count<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,bool>> predicate);
static member Count : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, bool>> -> int
<Extension()>
Public Function Count(Of TSource) (source As IQueryable(Of TSource), predicate As Expression(Of Func(Of TSource, Boolean))) As Integer

형식 매개 변수

TSource

source 요소의 형식입니다.The type of the elements of source.

매개 변수

source
IQueryable<TSource>

개수를 셀 요소가 들어 있는 IQueryable<T>입니다.An IQueryable<T> that contains the elements to be counted.

predicate
Expression<Func<TSource,Boolean>>

각 요소를 조건에 대해 테스트하는 함수입니다.A function to test each element for a condition.

반환

Int32

시퀀스에서 조건자 함수의 조건에 맞는 요소 수입니다.The number of elements in the sequence that satisfies the condition in the predicate function.

예외

source 또는 predicatenull인 경우source or predicate is null.

source의 요소 수가 MaxValue보다 큰 경우The number of elements in source is larger than MaxValue.

예제

다음 코드 예제에서는를 사용 하 여 Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) 조건에 맞는 시퀀스에서 요소를 계산 하는 방법을 보여 줍니다.The following code example demonstrates how to use Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) to count the elements in a sequence that satisfy a condition.

class Pet
{
    public string Name { get; set; }
    public bool Vaccinated { get; set; }
}

public static void CountEx2()
{
    // Create an array of Pet objects.
    Pet[] pets = { new Pet { Name="Barley", Vaccinated=true },
                   new Pet { Name="Boots", Vaccinated=false },
                   new Pet { Name="Whiskers", Vaccinated=false } };

    // Count the number of unvaccinated pets in the array.
    int numberUnvaccinated =
        pets.AsQueryable().Count(p => p.Vaccinated == false);

    Console.WriteLine(
        "There are {0} unvaccinated animals.",
        numberUnvaccinated);
}

// This code produces the following output:
//
// There are 2 unvaccinated animals.

Structure Pet
    Public Name As String
    Public Vaccinated As Boolean
End Structure

Shared Sub CountEx2()
    ' Create an array of Pet objects.
    Dim pets() As Pet = {New Pet With {.Name = "Barley", .Vaccinated = True}, _
                   New Pet With {.Name = "Boots", .Vaccinated = False}, _
                   New Pet With {.Name = "Whiskers", .Vaccinated = False}}

    ' Count the number of unvaccinated pets in the array.
    Dim numberUnvaccinated As Integer = pets.AsQueryable().Count(Function(p) p.Vaccinated = False)

    MsgBox(String.Format("There are {0} unvaccinated animals.", numberUnvaccinated))
End Sub

' This code produces the following output:
'
' There are 2 unvaccinated animals.

설명

이 메서드에 형식 인수가 형식 중 하나인 형식의 매개 변수가 하나 이상 있습니다 Expression<TDelegate> Func<T,TResult> .This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. 이러한 매개 변수는 람다 식을 전달할 수 있으며로 컴파일됩니다 Expression<TDelegate> .For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)메서드는 자신을 MethodCallExpression 생성 된 제네릭 메서드로 호출 하는을 생성 합니다 Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) .The Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method generates a MethodCallExpression that represents calling Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) itself as a constructed generic method. 그런 다음 MethodCallExpression Execute<TResult>(Expression) IQueryProvider Provider 매개 변수의 속성이 나타내는의 메서드에를 전달 합니다 source .It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

호출을 나타내는 식 트리를 실행 한 결과로 발생 하는 쿼리 동작은 Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) 매개 변수의 형식 구현에 따라 달라 집니다 source .The query behavior that occurs as a result of executing an expression tree that represents calling Count<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) depends on the implementation of the type of the source parameter. 예상 되는 동작은에 source 지정 된 조건을 만족 하는의 항목 수를 계산 하는 것입니다 predicate .The expected behavior is that it counts the number of items in source that satisfy the condition specified by predicate.

적용 대상