Enumerable.Intersect Enumerable.Intersect Enumerable.Intersect Enumerable.Intersect Method

定義

產生兩個序列的交集。Produces the set intersection of two sequences.

多載

Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) 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。Produces the set intersection of two sequences by using the specified IEqualityComparer<T> to compare values.

Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) 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。Produces the set intersection of two sequences by using the default equality comparer to compare values.

備註

注意

本文中的某些 C# 範例會在 Try.NET 內嵌程式碼執行器和測試區執行。Some of the C# examples in this article run in the Try.NET inline code runner and playground. 請選取 [執行] 按鈕 (若該按鈕存在) 以在互動式視窗中執行範例。When present, select the Run button to run an example in an interactive window. 執行程式碼之後,您便可以修改它,並再選取一次 [執行] 來執行修改過的程式碼。Once you execute the code, you can modify it and run the modified code by selecting Run again. 修改過的程式碼會在互動式視窗中執行,或是如果編譯失敗的話,互動式視窗會顯示所有 C# 編譯器錯誤訊息。The modified code either runs in the interactive window or, if compilation fails, the interactive window displays all C# compiler error messages.

Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>) 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。Produces the set intersection 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> ^ 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);
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。The type of the elements of the input sequences.

參數

first
IEnumerable<TSource>

傳回其獨特項目同時出現在 second 中的 IEnumerable<T>An IEnumerable<T> whose distinct elements that also appear in second will be returned.

second
IEnumerable<TSource>

傳回其獨特項目同時出現在第一個序列中的 IEnumerable<T>An IEnumerable<T> whose distinct elements that also appear in the first sequence will be returned.

comparer
IEqualityComparer<TSource>

用來比較值的 IEqualityComparer<T>An IEqualityComparer<T> to compare values.

傳回

IEnumerable<TSource>

序列,其中包含形成兩個序列之交集的項目。A sequence that contains the elements that form the set intersection of two sequences.

例外狀況

firstsecondnullfirst or second is null.

範例

下列範例示範如何實作可用於相等比較子Intersect方法。The following example shows how to implement an equality comparer that can be used in the Intersect 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

實作這個比較子之後,您可以使用連串Product中的物件Intersect方法,如下列範例所示:After you implement this comparer, you can use sequences of Product objects in the Intersect method, as shown in the following example:

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 } };
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.

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
*/
' 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

實作這個方法是使用延後的執行。This method is implemented by using deferred execution. 立即傳回值是儲存,才能執行此動作的所有資訊的物件。The immediate return value is an object that stores all the information that is required to perform the action. 這個方法所表示的查詢不會執行直到列舉物件可以藉由呼叫其GetEnumerator方法直接或透過foreachVisual C# 中或For EachVisual Basic 中。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.

A 與 B 兩個集合的交集會定義為包含所有項目同時出現在 B,但沒有其他項目集。The intersection of two sets A and B is defined as the set that contains all the elements of A that also appear in B, but no other elements.

這個方法所傳回的物件列舉時,Intersect會產生不同的項目中兩個序列中出現的順序發生firstWhen the object returned by this method is enumerated, Intersect yields distinct elements occurring in both sequences in the order in which they appear in first.

如果comparernull,預設的相等比較子, Default,用來比較值。If comparer is null, the default equality comparer, Default, is used to compare values.

Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) 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。Produces the set intersection 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> ^ 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。The type of the elements of the input sequences.

參數

first
IEnumerable<TSource>

傳回其獨特項目同時出現在 second 中的 IEnumerable<T>An IEnumerable<T> whose distinct elements that also appear in second will be returned.

second
IEnumerable<TSource>

傳回其獨特項目同時出現在第一個序列中的 IEnumerable<T>An IEnumerable<T> whose distinct elements that also appear in the first sequence will be returned.

傳回

IEnumerable<TSource>

序列,其中包含形成兩個序列之交集的項目。A sequence that contains the elements that form the set intersection of two sequences.

例外狀況

firstsecondnullfirst or second is null.

範例

下列程式碼範例示範如何使用Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)傳回項目出現在每個整數的兩個序列中。The following code example demonstrates how to use Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>) to return the elements that appear in each of two sequences of integers.

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.
MsgBox(output.ToString)

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

如果您想要比較之物件的某些自訂資料類型的序列,您必須實作IEquatable<T>協助程式類別中的泛型介面。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. 下列程式碼範例示範如何自訂資料型別中實作此介面並覆寫GetHashCodeEquals方法。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

您實作這個介面之後,您可以使用的序列ProductA中的物件Intersect方法,如下列範例所示:After you implement this interface, you can use sequences of ProductA objects in the Intersect method, as shown in the following example:

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

實作這個方法是使用延後的執行。This method is implemented by using deferred execution. 立即傳回值是儲存,才能執行此動作的所有資訊的物件。The immediate return value is an object that stores all the information that is required to perform the action. 這個方法所表示的查詢不會執行直到列舉物件可以藉由呼叫其GetEnumerator方法直接或透過foreachVisual C# 中或For EachVisual Basic 中。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.

A 與 B 兩個集合的交集會定義為包含所有項目同時出現在 B,但沒有其他項目集。The intersection of two sets A and B is defined as the set that contains all the elements of A that also appear in B, but no other elements.

這個方法所傳回的物件列舉時,Intersect會產生不同的項目中兩個序列中出現的順序發生firstWhen the object returned by this method is enumerated, Intersect yields distinct elements occurring in both sequences in the order in which they appear in first.

預設相等比較子, Default,用來比較類型的值。The default equality comparer, Default, is used to compare values of the types. 若要比較的自訂資料類型,您需要覆寫EqualsGetHashCode方法,並選擇性地實作IEquatable<T>自訂型別中的泛型介面。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. 如需詳細資訊,請參閱 Default 屬性 (Property)。For more information, see the Default property.

適用於