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

定义

生成两个序列的交集。Produces the set intersection of two sequences.

重载

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>)

通过使用指定的 IEqualityComparer<T> 对值进行比较,生成两个序列的交集。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>)

通过使用默认的相等比较器对值进行比较,生成两个序列的交集。Produces the set intersection of two sequences by using the default equality comparer to compare values.

注解

备注

本文中的一些 C# 示例在 Try.NET 内联代码运行程序和演练环境中运行。Some of the C# examples in this article run in the Try.NET inline code runner and playground. 选择“运行” 按钮(若有),在交互式窗口中运行示例。When present, select the Run button to run an example in an interactive window. 执行代码后,可通过再次选择“运行”来修改它并运行已修改的代码 。Once you execute the code, you can modify it and run the modified code by selecting Run again. 已修改的代码要么在交互窗口中运行,要么编译失败时,交互窗口将显示所有 C# 编译器错误消息。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>)

通过使用指定的 IEqualityComparer<T> 对值进行比较,生成两个序列的交集。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)

类型参数

TSource

输入序列中的元素的类型。The type of the elements of the input sequences.

参数

first
IEnumerable<TSource>

一个 IEnumerable<T>,将返回其也出现在 second 中的非重复元素。An IEnumerable<T> whose distinct elements that also appear in second will be returned.

second
IEnumerable<TSource>

一个 IEnumerable<T> 序列,其中的同时出现在第一个序列中的非重复元素将被返回。An IEnumerable<T> whose distinct elements that also appear in the first sequence will be returned.

comparer
IEqualityComparer<TSource>

用于比较值的 IEqualityComparer<T>An IEqualityComparer<T> to compare values.

返回

IEnumerable<TSource>

包含组成两个序列交集的元素的序列。A sequence that contains the elements that form the set intersection of two sequences.

异常

firstsecondnullfirst or second is null.

示例

下面的示例演示如何实现可在Intersect方法中使用的相等比较器。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

实现此比较器后, 可以Product Intersect在方法中使用对象序列, 如以下示例中所示: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
' 

注解

此方法是使用延迟执行实现的。This method is implemented by using deferred execution. 即时返回值是一个对象, 该对象存储执行操作所需的所有信息。The immediate return value is an object that stores all the information that is required to perform the action. 此方法表示的查询在枚举对象之前不会执行, 方法是直接调用其GetEnumerator方法, 或者通过在foreach视觉C#对象中For Each或在 Visual Basic 中使用。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.

两个集 A 和 B 的交集被定义为包含中的所有元素的集合, 这些元素也出现在 B 中, 但没有其他元素。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.

枚举此方法返回的对象时, Intersect会按它们first出现的顺序产生两个序列中的非重复元素。When 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comparer Defaultnull, 则使用默认的相等比较器对值进行比较。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>)

通过使用默认的相等比较器对值进行比较,生成两个序列的交集。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)

类型参数

TSource

输入序列中的元素的类型。The type of the elements of the input sequences.

参数

first
IEnumerable<TSource>

一个 IEnumerable<T>,将返回其也出现在 second 中的非重复元素。An IEnumerable<T> whose distinct elements that also appear in second will be returned.

second
IEnumerable<TSource>

一个 IEnumerable<T> 序列,其中的同时出现在第一个序列中的非重复元素将被返回。An IEnumerable<T> whose distinct elements that also appear in the first sequence will be returned.

返回

IEnumerable<TSource>

包含组成两个序列交集的元素的序列。A sequence that contains the elements that form the set intersection of two sequences.

异常

firstsecondnullfirst or second is null.

示例

下面的代码示例演示如何使用Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)来返回出现在两个整数序列中的元素。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

如果要比较某种自定义数据类型的对象序列, 则必须在 helper 类中实现IEquatable<T>泛型接口。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. 下面的代码示例演示如何在自定义数据类型中实现此接口并重写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

实现此接口后, 可以ProductA Intersect在方法中使用对象序列, 如以下示例中所示: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
' 

注解

此方法是使用延迟执行实现的。This method is implemented by using deferred execution. 即时返回值是一个对象, 该对象存储执行操作所需的所有信息。The immediate return value is an object that stores all the information that is required to perform the action. 此方法表示的查询在枚举对象之前不会执行, 方法是直接调用其GetEnumerator方法, 或者通过在foreach视觉C#对象中For Each或在 Visual Basic 中使用。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.

两个集 A 和 B 的交集被定义为包含中的所有元素的集合, 这些元素也出现在 B 中, 但没有其他元素。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.

枚举此方法返回的对象时, Intersect会按它们first出现的顺序产生两个序列中的非重复元素。When 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.

默认的相等比较器Default用于比较类型的值。The default equality comparer, Default, is used to compare values of the types. 若要比较自定义数据类型, 需要重写Equals GetHashCode和方法, 还可以选择实现自定义IEquatable<T>类型中的泛型接口。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. 有关更多信息,请参见 Default 属性。For more information, see the Default property.

适用于