Enumerable.Intersect 方法

定義

產生兩個序列的交集。

多載

Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)

使用預設相等比較子來比較值,以便產生兩個序列的交集。

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

使用指定的 IEqualityComparer<T> 來比較值,以便產生兩個序列的交集。

Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)

使用預設相等比較子來比較值,以便產生兩個序列的交集。

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

類型參數

TSource

輸入序列之項目的類型。

參數

first
IEnumerable<TSource>

傳回其獨特項目同時出現在 second 中的 IEnumerable<T>

second
IEnumerable<TSource>

傳回其獨特項目同時出現在第一個序列中的 IEnumerable<T>

傳回

IEnumerable<TSource>

序列,其中包含形成兩個序列之交集的項目。

例外狀況

firstsecondnull

範例

下列程式碼範例示範如何使用 Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) 傳回出現在兩個整數序列中的專案。

int[] id1 = { 44, 26, 92, 30, 71, 38 };
int[] id2 = { 39, 59, 83, 47, 26, 4, 30 };

IEnumerable<int> both = id1.Intersect(id2);

foreach (int id in both)
    Console.WriteLine(id);

/*
 This code produces the following output:

 26
 30
*/
' Create two integer arrays.
Dim id1() As Integer = {44, 26, 92, 30, 71, 38}
Dim id2() As Integer = {39, 59, 83, 47, 26, 4, 30}

' Find the set intersection of the two arrays.
Dim intersection As IEnumerable(Of Integer) = id1.Intersect(id2)

Dim output As New System.Text.StringBuilder
For Each id As Integer In intersection
    output.AppendLine(id)
Next

' Display the output.
Console.WriteLine(output.ToString)

' This code produces the following output:
'
' 26
' 30

如果您想要比較某些自訂資料類型的物件序列,您必須在協助程式類別中實 IEquatable<T> 作泛型介面。 下列程式碼範例示範如何在自訂資料類型中實作此介面,並覆寫 GetHashCodeEquals 方法。

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

實作此介面之後,您可以在 方法中使用 Intersect 物件的序列 ProductA ,如下列範例所示:

ProductA[] store1 = { new ProductA { Name = "apple", Code = 9 },
                       new ProductA { Name = "orange", Code = 4 } };

ProductA[] store2 = { new ProductA { Name = "apple", Code = 9 },
                       new ProductA { Name = "lemon", Code = 12 } };
Dim store1() As ProductA = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}}

Dim store2() As ProductA = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "lemon", .Code = 12}}
// Get the products from the first array
// that have duplicates in the second array.

IEnumerable<ProductA> duplicates =
    store1.Intersect(store2);

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

/*
    This code produces the following output:
    apple 9
*/
' Get the products from the first array 
' that have duplicates in the second array.

Dim duplicates = store1.Intersect(store2)

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

' This code produces the following output:
'
' apple 9
'

備註

此方法是使用延後執行來實作。 立即傳回值是物件,可儲存執行動作所需的所有資訊。 除非直接在 GetEnumerator Visual C# 中或使用 Visual C# 或 Visual Basic 來列舉物件,否則 For Each 不會執行這個方法 foreach 所表示的查詢。

兩個集合 A 和 B 的交集定義為集合,其中包含也出現在 B 中的所有 A 元素,但沒有其他元素。

列舉這個方法所傳回的物件時, Intersect 會產生兩個序列中出現的不同元素,其出現在 的順序。 first

預設相等比較子 Default 是用來比較型別的值。 若要比較自訂資料類型,您必須覆寫 EqualsGetHashCode 方法,並選擇性地在自訂類型中實 IEquatable<T> 作泛型介面。 如需詳細資訊,請參閱 Default 屬性 (Property)。

適用於

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

使用指定的 IEqualityComparer<T> 來比較值,以便產生兩個序列的交集。

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

類型參數

TSource

輸入序列之項目的類型。

參數

first
IEnumerable<TSource>

傳回其獨特項目同時出現在 second 中的 IEnumerable<T>

second
IEnumerable<TSource>

傳回其獨特項目同時出現在第一個序列中的 IEnumerable<T>

comparer
IEqualityComparer<TSource>

用來比較值的 IEqualityComparer<T>

傳回

IEnumerable<TSource>

序列,其中包含形成兩個序列之交集的項目。

例外狀況

firstsecondnull

範例

下列範例示範如何實作方法中 Intersect 可使用的相等比較子。

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

實作這個比較子之後,您可以在 方法中使用 Intersect 物件的序列 Product ,如下列範例所示:

Product[] store1 = { new Product { Name = "apple", Code = 9 },
                       new Product { Name = "orange", Code = 4 } };

Product[] store2 = { new Product { Name = "apple", Code = 9 },
                       new Product { Name = "lemon", Code = 12 } };

// Get the products from the first array
// that have duplicates in the second array.

IEnumerable<Product> duplicates =
    store1.Intersect(store2, new ProductComparer());

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

/*
    This code produces the following output:
    apple 9
*/
Dim store1() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "orange", .Code = 4}}

Dim store2() As Product = 
    {New Product With {.Name = "apple", .Code = 9}, 
     New Product With {.Name = "lemon", .Code = 12}}
' Get the products from the first array 
' that have duplicates in the second array.

Dim duplicates = store1.Intersect(store2, New ProductComparer())

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

' This code produces the following output:
'
' apple 9
'

備註

此方法是使用延後執行來實作。 立即傳回值是物件,可儲存執行動作所需的所有資訊。 除非直接在 GetEnumerator Visual C# 中或使用 Visual C# 或 Visual Basic 來列舉物件,否則 For Each 不會執行這個方法 foreach 所表示的查詢。

兩個集合 A 和 B 的交集定義為集合,其中包含也出現在 B 中的所有 A 元素,但沒有其他元素。

列舉這個方法所傳回的物件時, Intersect 會產生兩個序列中出現的不同元素,其出現在 的順序。 first

如果 comparernull ,則會使用 預設相等比較子 Default 來比較值。

適用於