Enumerable.Except Enumerable.Except Enumerable.Except Enumerable.Except Method

Definição

Produz a diferença de conjunto de duas sequências.Produces the set difference of two sequences.

Sobrecargas

Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)

Produz a diferença de conjunto de duas sequências usando o comparador de igualdade padrão para comparar os valores.Produces the set difference of two sequences by using the default equality comparer to compare values.

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

Produz a diferença de conjunto de duas sequências usando o IEqualityComparer<T> especificado para comparar os valores.Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.

Comentários

A diferença de conjunto de dois conjuntos é definida como os membros do primeiro conjunto que não são exibidos no segundo conjunto.The set difference of two sets is defined as the members of the first set that don't appear in the second set.

Esse método retorna os elementos na first que não são exibidas no second.This method returns those elements in first that don't appear in second. Ele não retorna os elementos na second que não são exibidas no first.It doesn't return those elements in second that don't appear in first. Apenas elementos exclusivos são retornados.Only unique elements are returned.

Observação

Alguns dos exemplos de C# neste artigo são executados no executador de código embutido Try.NET e no playground.Some of the C# examples in this article run in the Try.NET inline code runner and playground. Quando presente, selecione o botão Executar para executar um exemplo em uma janela interativa.When present, select the Run button to run an example in an interactive window. Ao executar o código, é possível modificá-lo e executar o código modificado clicando em Executar novamente.Once you execute the code, you can modify it and run the modified code by selecting Run again. O código modificado será executado na janela interativa ou, se a compilação falhar, a janela interativa exibirá todos as mensagens de erro do compilador C#.The modified code either runs in the interactive window or, if compilation fails, the interactive window displays all C# compiler error messages.

Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)

Produz a diferença de conjunto de duas sequências usando o comparador de igualdade padrão para comparar os valores.Produces the set difference of two sequences by using the default equality comparer to compare values.

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

Parâmetros de tipo

TSource

O tipo dos elementos das sequências de entrada.The type of the elements of the input sequences.

Parâmetros

first
IEnumerable<TSource>

Um IEnumerable<T> cujos elementos que não estão presentes também no second serão retornados.An IEnumerable<T> whose elements that are not also in second will be returned.

second
IEnumerable<TSource>

Um IEnumerable<T> cujos elementos que também ocorrem na primeira sequência farão com que esses elementos sejam removidos da sequência retornada.An IEnumerable<T> whose elements that also occur in the first sequence will cause those elements to be removed from the returned sequence.

Retornos

IEnumerable<TSource>

Uma sequência que contém a diferença de conjunto dos elementos das duas sequências.A sequence that contains the set difference of the elements of two sequences.

Exceções

Exemplos

O exemplo de código a seguir demonstra como usar o Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) método para comparar duas sequências de números e retornar elementos que aparecem somente na primeira sequência.The following code example demonstrates how to use the Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) method to compare two sequences of numbers and return elements that appear only in the first sequence.

double[] numbers1 = { 2.0, 2.0, 2.1, 2.2, 2.3, 2.3, 2.4, 2.5 };
double[] numbers2 = { 2.2 };

IEnumerable<double> onlyInFirstSet = numbers1.Except(numbers2);

foreach (double number in onlyInFirstSet)
    Console.WriteLine(number);

/*
 This code produces the following output:

 2
 2.1
 2.3
 2.4
 2.5
*/
' Create two arrays of doubles.
Dim numbers1() As Double = { 2.0, 2.0, 2.1, 2.2, 2.3, 2.3, 2.4, 2.5 }
Dim numbers2() As Double = {2.2}

' Select the elements from the first array that are not
' in the second array.
Dim onlyInFirstSet As IEnumerable(Of Double) = numbers1.Except(numbers2)

Dim output As New System.Text.StringBuilder
For Each number As Double In onlyInFirstSet
    output.AppendLine(number)
Next

' Display the output.
MsgBox(output.ToString())

' This code produces the following output:
'
' 2
' 2.1
' 2.3
' 2.4
' 2.5

Se você quiser comparar sequências de objetos de algum tipo de dados personalizado, você precisa implementar o IEquatable<T> interface genérica em uma classe auxiliar.If you want to compare sequences of objects of some custom data type, you have to implement the IEquatable<T> generic interface in a helper class. O exemplo de código a seguir mostra como implementar essa interface em um tipo de dados personalizado e substituir GetHashCode e Equals métodos.The following code example shows how to implement this interface in a custom data type and override GetHashCode and Equals methods.

public class ProductA: IEquatable<ProductA>
{
    public string Name { get; set; }
    public int Code { get; set; }

    public bool Equals(ProductA other)
    {
        if (other is null)
            return false;

        return this.Name == other.Name && this.Code == other.Code;
    }

    public override bool Equals(object obj) => Equals(obj as ProductA);
    public override int GetHashCode() => (Name, Code).GetHashCode();
}
Public Class ProductA
    Inherits IEquatable(Of ProductA)

    Public Property Name As String
    Public Property Code As Integer

    Public Function Equals(ByVal other As ProductA) As Boolean
        If other Is Nothing Then Return False
        Return Me.Name = other.Name AndAlso Me.Code = other.Code
    End Function

    Public Overrides Function Equals(ByVal obj As Object) As Boolean
        Return Equals(TryCast(obj, ProductA))
    End Function

    Public Overrides Function GetHashCode() As Integer
        Return (Name, Code).GetHashCode()
    End Function

End Class

Depois de implementar essa interface, você pode usar sequências de ProductA objetos no Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) método, conforme mostrado no exemplo a seguir:After you implement this interface, you can use sequences of ProductA objects in the Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) method, as shown in the following example:

ProductA[] fruits1 = { new ProductA { Name = "apple", Code = 9 }, 
                       new ProductA { Name = "orange", Code = 4 },
                        new ProductA { Name = "lemon", Code = 12 } };

ProductA[] fruits2 = { new ProductA { Name = "apple", Code = 9 } };

//Get all the elements from the first array
//except for the elements from the second array.

IEnumerable<ProductA> except =
    fruits1.Except(fruits2);

foreach (var product in except)
    Console.WriteLine(product.Name + " " + product.Code);

/*
  This code produces the following output:
 
  orange 4
  lemon 12
*/
Dim fruits1() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}, 
     New Product With {.Name = "lemon", .Code = 12}}

Dim fruits2() As Product = 
    {New Product With {.Name = "apple", .Code = 9}}

' Get all the elements from the first array
' except for the elements from the second array.

Dim except = fruits1.Except(fruits2)

For Each product In except
    Console.WriteLine(product.Name & " " & product.Code)
Next

' This code produces the following output:
'
' apple 9
' orange 4
' lemon 12

Comentários

Esse método é implementado usando a execução adiada.This method is implemented by using deferred execution. O imediata valor retornado é um objeto que armazena todas as informações necessárias para executar a ação.The immediate return value is an object that stores all the information that is required to perform the action. A consulta representada por esse método não é executada até que o objeto é enumerado chamando-se suas GetEnumerator método diretamente ou usando foreach no Visual c# ou For Each no Visual Basic.The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

O comparador de igualdade padrão, Default, é usado para comparar valores de tipos.The default equality comparer, Default, is used to compare values of the types. Para comparar um tipo de dados personalizado, você precisa substituir os Equals e o GetHashCode métodos e, opcionalmente, implemente o IEquatable<T> interface genérica de tipo personalizado.To compare a custom data type, you need to override the Equals and the GetHashCode methods, and optionally implement the IEquatable<T> generic interface in the custom type. Para obter mais informações, consulte a propriedade Default.For more information, see the Default property.

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

Produz a diferença de conjunto de duas sequências usando o IEqualityComparer<T> especificado para comparar os valores.Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.

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

Parâmetros de tipo

TSource

O tipo dos elementos das sequências de entrada.The type of the elements of the input sequences.

Parâmetros

first
IEnumerable<TSource>

Um IEnumerable<T> cujos elementos que não estão presentes também no second serão retornados.An IEnumerable<T> whose elements that are not also in second will be returned.

second
IEnumerable<TSource>

Um IEnumerable<T> cujos elementos que também ocorrem na primeira sequência farão com que esses elementos sejam removidos da sequência retornada.An IEnumerable<T> whose elements that also occur in the first sequence will cause those elements to be removed from the returned sequence.

comparer
IEqualityComparer<TSource>

Um IEqualityComparer<T> para comparar valores.An IEqualityComparer<T> to compare values.

Retornos

IEnumerable<TSource>

Uma sequência que contém a diferença de conjunto dos elementos das duas sequências.A sequence that contains the set difference of the elements of two sequences.

Exceções

Exemplos

Se você quiser comparar sequências de objetos de algum tipo de dados personalizado, você precisa implementar o IEqualityComparer<T> interface genérica em uma classe auxiliar.If you want to compare sequences of objects of some custom data type, you have to implement the IEqualityComparer<T> generic interface in a helper class. O exemplo de código a seguir mostra como implementar essa interface em um tipo de dados personalizadas e fornecer GetHashCode e Equals métodos.The following code example shows how to implement this interface in a custom data type and provide GetHashCode and Equals methods. O exemplo a seguir mostra como implementar um comparador de igualdade que pode ser usado no Except método.The following example shows how to implement an equality comparer that can be used in the Except 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 sequências de Product objetos no Except método, conforme mostrado no exemplo a seguir:After you implement this comparer, you can use sequences of Product objects in the Except method, as shown in the following example:

Product[] fruits1 = { new Product { Name = "apple", Code = 9 }, 
                       new Product { Name = "orange", Code = 4 },
                        new Product { Name = "lemon", Code = 12 } };

Product[] fruits2 = { new Product { Name = "apple", Code = 9 } };

//Get all the elements from the first array
//except for the elements from the second array.

IEnumerable<Product> except =
    fruits1.Except(fruits2, new ProductComparer());

foreach (var product in except)
    Console.WriteLine(product.Name + " " + product.Code);

/*
  This code produces the following output:
 
  orange 4
  lemon 12
*/

Dim fruits1() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}, 
     New Product With {.Name = "lemon", .Code = 12}}

Dim fruits2() As Product = 
    {New Product With {.Name = "apple", .Code = 9}}

' Get all the elements from the first array
' except for the elements from the second array.

Dim except = fruits1.Except(fruits2, New ProductComparer())

For Each product In except
    Console.WriteLine(product.Name & " " & product.Code)
Next

' This code produces the following output:
'
' orange 4
' lemon 12

Comentários

Se comparer está null, o comparador de igualdade padrão, Default, é usado para comparar valores.If comparer is null, the default equality comparer, Default, is used to compare values.

Aplica-se a