Enumerable.Except 메서드

정의

두 시퀀스의 차집합을 구합니다.Produces the set difference of two sequences.

오버로드

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

기본 같음 비교자를 사용 하 여 값을 비교 하 여 두 시퀀스의 차집합을 구합니다.Produces the set difference of two sequences by using the default equality comparer to compare values.

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

지정된 IEqualityComparer<T>로 값을 비교하여 두 시퀀스의 차집합을 구합니다.Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.

설명

두 집합의 차 집합은 두 번째 집합에 표시 되지 않는 첫 번째 집합의 멤버로 정의 됩니다.The set difference of two sets is defined as the members of the first set that don't appear in the second set.

이 메서드는 second에 표시 되지 않는 first의 요소를 반환 합니다.This method returns those elements in first that don't appear in second. first에 표시 되지 않는 second 요소는 반환 하지 않습니다.It doesn't return those elements in second that don't appear in first. 고유 요소만 반환 됩니다.Only unique elements are returned.

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

기본 같음 비교자를 사용 하 여 값을 비교 하 여 두 시퀀스의 차집합을 구합니다.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)

형식 매개 변수

TSource

입력 시퀀스 요소의 형식입니다.The type of the elements of the input sequences.

매개 변수

first
IEnumerable<TSource>

second에 없는 해당 요소를 반환할 IEnumerable<T>입니다.An IEnumerable<T> whose elements that are not also in second will be returned.

second
IEnumerable<TSource>

첫 번째 시퀀스에 해당 요소가 있는 경우 반환되는 시퀀스에서 해당 요소를 제거할 IEnumerable<T>입니다.An IEnumerable<T> whose elements that also occur in the first sequence will cause those elements to be removed from the returned sequence.

반환

IEnumerable<TSource>

두 시퀀스 요소의 차집합이 들어 있는 시퀀스입니다.A sequence that contains the set difference of the elements of two sequences.

예외

first 또는 secondnull인 경우first or second is null.

예제

다음 코드 예제에서는 Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) 메서드를 사용 하 여 두 시퀀스를 비교 하 고 첫 번째 시퀀스 에서만 표시 되는 요소를 반환 하는 방법을 보여 줍니다.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.
Console.WriteLine(output.ToString())

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

일부 사용자 지정 데이터 형식의 개체 시퀀스를 비교 하려면 도우미 클래스에서 IEquatable<T> 제네릭 인터페이스를 구현 해야 합니다.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. 다음 코드 예제에서는 사용자 지정 데이터 형식에서이 인터페이스를 구현 하 고 GetHashCodeEquals 메서드를 재정의 하는 방법을 보여 줍니다.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

이 인터페이스를 구현한 후에는 다음 예제와 같이 Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) 메서드에서 ProductA 개체의 시퀀스를 사용할 수 있습니다.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

설명

이 메서드는 지연 된 실행을 사용 하 여 구현 됩니다.This method is implemented by using deferred execution. 즉시 반환 값은 작업을 수행 하는 데 필요한 모든 정보를 저장 하는 개체입니다.The immediate return value is an object that stores all the information that is required to perform the action. 이 메서드를 나타내는 쿼리 하거나 호출 하 여 개체 열거 될 때까지 실행 되지 않습니다 해당 GetEnumerator 메서드를 사용 하 여 직접 또는 foreach Visual C# 또는 For Each Visual Basic의 합니다.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.

기본 같음 비교자 인 Default는 형식의 값을 비교 하는 데 사용 됩니다.The default equality comparer, Default, is used to compare values of the types. 사용자 지정 데이터 형식을 비교 하려면 EqualsGetHashCode 메서드를 재정의 하 고, 선택적으로 사용자 지정 형식에서 IEquatable<T> 제네릭 인터페이스를 구현 해야 합니다.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. 자세한 내용은 Default 속성을 참조하세요.For more information, see the Default property.

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

지정된 IEqualityComparer<T>로 값을 비교하여 두 시퀀스의 차집합을 구합니다.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)

형식 매개 변수

TSource

입력 시퀀스 요소의 형식입니다.The type of the elements of the input sequences.

매개 변수

first
IEnumerable<TSource>

second에 없는 해당 요소를 반환할 IEnumerable<T>입니다.An IEnumerable<T> whose elements that are not also in second will be returned.

second
IEnumerable<TSource>

첫 번째 시퀀스에 해당 요소가 있는 경우 반환되는 시퀀스에서 해당 요소를 제거할 IEnumerable<T>입니다.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>

값을 비교할 IEqualityComparer<T> 입니다.An IEqualityComparer<T> to compare values.

반환

IEnumerable<TSource>

두 시퀀스 요소의 차집합이 들어 있는 시퀀스입니다.A sequence that contains the set difference of the elements of two sequences.

예외

first 또는 secondnull인 경우first or second is null.

예제

일부 사용자 지정 데이터 형식의 개체 시퀀스를 비교 하려면 도우미 클래스에서 IEqualityComparer<T> 제네릭 인터페이스를 구현 해야 합니다.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. 다음 코드 예제에서는 사용자 지정 데이터 형식에서이 인터페이스를 구현 하 고 GetHashCodeEquals 메서드를 제공 하는 방법을 보여 줍니다.The following code example shows how to implement this interface in a custom data type and provide GetHashCode and Equals methods. 다음 예제에서는 Except 메서드에서 사용할 수 있는 같음 비교자를 구현 하는 방법을 보여 줍니다.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

이 비교자를 구현한 후에는 다음 예제와 같이 Except 메서드에서 Product 개체의 시퀀스를 사용할 수 있습니다.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

설명

comparer null되는 경우 기본 같음 비교자 Default를 사용 하 여 값을 비교 합니다.If comparer is null, the default equality comparer, Default, is used to compare values.

적용 대상