Enumerable.Count Método

Definición

Espacio de nombres:
System.Linq
Ensamblado:
System.Linq.dll
Ensamblado:
System.Core.dll
Ensamblado:
netstandard.dll

Devuelve el número de elementos de una secuencia.Returns the number of elements in a sequence.

Sobrecargas

Count<TSource>(IEnumerable<TSource>)

Devuelve el número de elementos de una secuencia.Returns the number of elements in a sequence.
Count<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)

Devuelve un número que representa cuántos elementos de la secuencia especificada satisfacen una condición.Returns a number that represents how many elements in the specified sequence satisfy a condition.

Count<TSource>(IEnumerable<TSource>)

Devuelve el número de elementos de una secuencia.Returns the number of elements in a sequence.

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

Parámetros de tipo

TSource

Tipo de los elementos de source.The type of the elements of source.

Parámetros

source
IEnumerable<TSource>

Secuencia que contiene los elementos que se van a contar.A sequence that contains elements to be counted.

Devoluciones

Int32

El número de elementos de la secuencia de entrada.The number of elements in the input sequence.

Excepciones

ArgumentNullException

source es null.source is null.

OverflowException

El número de elementos de source es mayor que MaxValue.The number of elements in source is larger than MaxValue.

Ejemplos

En el ejemplo de código siguiente se muestra cómo usar Count<TSource>(IEnumerable<TSource>) para contar los elementos de una matriz.The following code example demonstrates how to use Count<TSource>(IEnumerable<TSource>) to count the elements in an array.

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

try
{
    int numberOfFruits = fruits.Count();
    Console.WriteLine(
        "There are {0} fruits in the collection.",
        numberOfFruits);
}
catch (OverflowException)
{
    Console.WriteLine("The count is too large to store as an Int32.");
    Console.WriteLine("Try using the LongCount() method instead.");
}

// 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"}

Try
    ' Count the number of items in the array.
    Dim numberOfFruits As Integer = fruits.Count()
    ' Display the output.
    Console.WriteLine($"There are {numberOfFruits} fruits in the collection.")
Catch e As OverflowException
    Console.WriteLine("The count is too large to store as an Int32. Try using LongCount() instead.")
End Try

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

Comentarios

Si el tipo de source implementa ICollection<T> , esa implementación se utiliza para obtener el recuento de elementos.If the type of source implements ICollection<T>, that implementation is used to obtain the count of elements. De lo contrario, este método determina el recuento.Otherwise, this method determines the count.

Use el LongCount método cuando lo espere y desee permitir que el resultado sea mayor que MaxValue .Use the LongCount method when you expect and want to allow the result to be greater than MaxValue.

En Visual Basic sintaxis de expresiones de consulta, una Aggregate Into Count() cláusula se convierte en una invocación de Count .In Visual Basic query expression syntax, an Aggregate Into Count() clause translates to an invocation of Count.

Consulte también

Se aplica a

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

Devuelve un número que representa cuántos elementos de la secuencia especificada satisfacen una condición.Returns a number that represents how many elements in the specified sequence satisfy a condition.

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

Parámetros de tipo

TSource

Tipo de los elementos de source.The type of the elements of source.

Parámetros

source
IEnumerable<TSource>

Secuencia que contiene los elementos que se van a probar y contar.A sequence that contains elements to be tested and counted.

predicate
Func<TSource,Boolean>

Función para probar cada elemento de una condición.A function to test each element for a condition.

Devoluciones

Int32

Un número que representa cuántos elementos de la secuencia especificada satisfacen la condición de la función de predicado.A number that represents how many elements in the sequence satisfy the condition in the predicate function.

Excepciones

ArgumentNullException

source o predicate es null.source or predicate is null.

OverflowException

El número de elementos de source es mayor que MaxValue.The number of elements in source is larger than MaxValue.

Ejemplos

En el ejemplo de código siguiente se muestra cómo usar Count<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) para contar los elementos de una matriz que satisfacen una condición.The following code example demonstrates how to use Count<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 bool Vaccinated { get; set; }
}

public static void CountEx2()
{
    Pet[] pets = { new Pet { Name="Barley", Vaccinated=true },
                   new Pet { Name="Boots", Vaccinated=false },
                   new Pet { Name="Whiskers", Vaccinated=false } };

    try
    {
        int numberUnvaccinated = pets.Count(p => p.Vaccinated == false);
        Console.WriteLine("There are {0} unvaccinated animals.", numberUnvaccinated);
    }
    catch (OverflowException)
    {
        Console.WriteLine("The count is too large to store as an Int32.");
        Console.WriteLine("Try using the LongCount() method instead.");
    }
}

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

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

Public 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}}

    Try
        ' Count the number of Pets in the array where the Vaccinated property is False.
        Dim numberUnvaccinated As Integer =
    pets.Count(Function(p) p.Vaccinated = False)
        ' Display the output.
        Console.WriteLine($"There are {numberUnvaccinated} unvaccinated animals.")
    Catch e As OverflowException
        Console.WriteLine("The count is too large to store as an Int32. Try using LongCount() instead.")
    End Try

End Sub

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

Comentarios

Si el tipo de source implementa ICollection<T> , esa implementación se utiliza para obtener el recuento de elementos.If the type of source implements ICollection<T>, that implementation is used to obtain the count of elements. De lo contrario, este método determina el recuento.Otherwise, this method determines the count.

Debe utilizar el LongCount método cuando lo espere y desee permitir que el resultado sea mayor que MaxValue .You should use the LongCount method when you expect and want to allow the result to be greater than MaxValue.

En Visual Basic sintaxis de expresiones de consulta, una Aggregate Into Count() cláusula se convierte en una invocación de Count .In Visual Basic query expression syntax, an Aggregate Into Count() clause translates to an invocation of Count.

Consulte también

Se aplica a