Enumerable.Contains Enumerable.Contains Enumerable.Contains Enumerable.Contains Method

Definição

Determina se uma sequência contém um elemento especificado.Determines whether a sequence contains a specified element.

Sobrecargas

Contains<TSource>(IEnumerable<TSource>, TSource) Contains<TSource>(IEnumerable<TSource>, TSource) Contains<TSource>(IEnumerable<TSource>, TSource) Contains<TSource>(IEnumerable<TSource>, TSource)

Determina se uma sequência contém um elemento especificado usando o comparador de igualdade padrão.Determines whether a sequence contains a specified element by using the default equality comparer.

Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>)

Determina se uma sequência contém um elemento especificado usando um IEqualityComparer<T> especificado.Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>.

Contains<TSource>(IEnumerable<TSource>, TSource) Contains<TSource>(IEnumerable<TSource>, TSource) Contains<TSource>(IEnumerable<TSource>, TSource) Contains<TSource>(IEnumerable<TSource>, TSource)

Determina se uma sequência contém um elemento especificado usando o comparador de igualdade padrão.Determines whether a sequence contains a specified element by using the default equality comparer.

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

Parâmetros de tipo

TSource

O tipo dos elementos de source.The type of the elements of source.

Parâmetros

source
IEnumerable<TSource>

Uma sequência na qual um valor será localizado.A sequence in which to locate a value.

value
TSource TSource TSource TSource

O valor a ser localizado na sequência.The value to locate in the sequence.

Retornos

true se a sequência de origem contiver um elemento que tem o valor especificado; caso contrário, false.true if the source sequence contains an element that has the specified value; otherwise, false.

Exceções

Exemplos

O exemplo de código a seguir demonstra como usar Contains<TSource>(IEnumerable<TSource>, TSource) para determinar se uma matriz contém um elemento específico.The following code example demonstrates how to use Contains<TSource>(IEnumerable<TSource>, TSource) to determine whether an array contains a specific element.

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

string fruit = "mango";

bool hasMango = fruits.Contains(fruit);

Console.WriteLine(
    "The array {0} contain '{1}'.",
    hasMango ? "does" : "does not",
    fruit);

// This code produces the following output:
//
// The array does contain 'mango'.
' Create an array of strings.
Dim fruits() As String = {"apple", "banana", "mango", "orange", "passionfruit", "grape"}

' This is the string to search the array for.
Dim fruit As String = "mango"

' Determine if the array contains the specified string.
Dim hasMango As Boolean = fruits.Contains(fruit)

Dim text As String = IIf(hasMango, "does", "does not")

' Display the output.
MsgBox("The array " & text & " contain " & fruit)

' This code produces the following output:
'
' The array does contain mango

Comentários

Se o tipo de source implementa ICollection<T>, o Contains método em que a implementação é chamado para obter o resultado.If the type of source implements ICollection<T>, the Contains method in that implementation is invoked to obtain the result. Caso contrário, este método determina se source contém o elemento especificado.Otherwise, this method determines whether source contains the specified element.

Enumeração será encerrada assim que um elemento correspondente for encontrado.Enumeration is terminated as soon as a matching element is found.

Elementos são comparados com o valor especificado usando o comparador de igualdade padrão, Default.Elements are compared to the specified value by using the default equality comparer, Default.

Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>) Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>)

Determina se uma sequência contém um elemento especificado usando um IEqualityComparer<T> especificado.Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>.

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

Parâmetros de tipo

TSource

O tipo dos elementos de source.The type of the elements of source.

Parâmetros

source
IEnumerable<TSource>

Uma sequência na qual um valor será localizado.A sequence in which to locate a value.

value
TSource TSource TSource TSource

O valor a ser localizado na sequência.The value to locate in the sequence.

comparer
IEqualityComparer<TSource>

Um comparador de igualdade para comparar valores.An equality comparer to compare values.

Retornos

true se a sequência de origem contiver um elemento que tem o valor especificado; caso contrário, false.true if the source sequence contains an element that has the specified value; otherwise, false.

Exceções

Exemplos

O exemplo a seguir mostra como implementar um comparador de igualdade que pode ser usado no Contains método.The following example shows how to implement an equality comparer that can be used in the Contains method.

public class Product
{
    public string Name { get; set; }
    public int Code { get; set; }
}

// Custom comparer for the Product class
class ProductComparer : IEqualityComparer<Product>
{
    // Products are equal if their names and product numbers are equal.
    public bool Equals(Product x, Product y)
    {
       
        //Check whether the compared objects reference the same data.
        if (Object.ReferenceEquals(x, y)) return true;

        //Check whether any of the compared objects is null.
        if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null))
            return false;

        //Check whether the products' properties are equal.
        return x.Code == y.Code && x.Name == y.Name;
    }

    // If Equals() returns true for a pair of objects 
    // then GetHashCode() must return the same value for these objects.

    public int GetHashCode(Product product)
    {
        //Check whether the object is null
        if (Object.ReferenceEquals(product, null)) return 0;

        //Get hash code for the Name field if it is not null.
        int hashProductName = product.Name == null ? 0 : product.Name.GetHashCode();

        //Get hash code for the Code field.
        int hashProductCode = product.Code.GetHashCode();

        //Calculate the hash code for the product.
        return hashProductName ^ hashProductCode;
    }

}
Public Class Product
    Public Property Name As String
    Public Property Code As Integer
End Class

' Custom comparer for the Product class
Public Class ProductComparer
    Implements IEqualityComparer(Of Product)

    Public Function Equals1(
        ByVal x As Product, 
        ByVal y As Product
        ) As Boolean Implements IEqualityComparer(Of Product).Equals

        ' Check whether the compared objects reference the same data.
        If x Is y Then Return True

        'Check whether any of the compared objects is null.
        If x Is Nothing OrElse y Is Nothing Then Return False

        ' Check whether the products' properties are equal.
        Return (x.Code = y.Code) AndAlso (x.Name = y.Name)
    End Function

    Public Function GetHashCode1(
        ByVal product As Product
        ) As Integer Implements IEqualityComparer(Of Product).GetHashCode

        ' Check whether the object is null.
        If product Is Nothing Then Return 0

        ' Get hash code for the Name field if it is not null.
        Dim hashProductName = 
            If(product.Name Is Nothing, 0, product.Name.GetHashCode())

        ' Get hash code for the Code field.
        Dim hashProductCode = product.Code.GetHashCode()

        ' Calculate the hash code for the product.
        Return hashProductName Xor hashProductCode
    End Function
End Class

Depois de implementar esse comparador, você pode usar uma sequência de Product objetos no Contains método, conforme mostrado no exemplo a seguir:After you implement this comparer, you can use a sequence of Product objects in the Contains method, as shown in the following example:


Product[] fruits = { new Product { Name = "apple", Code = 9 }, 
                       new Product { Name = "orange", Code = 4 }, 
                       new Product { Name = "lemon", Code = 12 } };

Product apple = new Product { Name = "apple", Code = 9 };
Product kiwi = new Product {Name = "kiwi", Code = 8 };

ProductComparer prodc = new ProductComparer();

bool hasApple = fruits.Contains(apple, prodc);
bool hasKiwi = fruits.Contains(kiwi, prodc);

Console.WriteLine("Apple? " + hasApple);
Console.WriteLine("Kiwi? " + hasKiwi);

/*
    This code produces the following output:
 
    Apple? True
    Kiwi? False
*/    


Dim fruits() As Product = 
   {New Product With {.Name = "apple", .Code = 9}, 
    New Product With {.Name = "orange", .Code = 4}, 
    New Product With {.Name = "lemon", .Code = 12}}

Dim apple = New Product With {.Name = "apple", .Code = 9}
Dim kiwi = New Product With {.Name = "kiwi", .Code = 8}

Dim prodc As New ProductComparer()

Dim hasApple = fruits.Contains(apple, prodc)
Dim hasKiwi = fruits.Contains(kiwi, prodc)

Console.WriteLine("Apple? " & hasApple)
Console.WriteLine("Kiwi? " & hasKiwi)


' This code produces the following output:
'
' Apple? True
' Kiwi? False

Comentários

Enumeração será encerrada assim que um elemento correspondente for encontrado.Enumeration is terminated as soon as a matching element is found.

Se comparer está null, o comparador de igualdade padrão, Default, é usado para comparar elementos para o valor especificado.If comparer is null, the default equality comparer, Default, is used to compare elements to the specified value.

Aplica-se a