Enumerable.Intersect<TSource> Method (IEnumerable<TSource>, IEnumerable<TSource>)

Type Parameters

• TSource
  The type of the elements of the input sequences.

Parameters

• first
  Type: System.Collections.Generic.IEnumerable<TSource>
  An IEnumerable<T> whose distinct elements that also appear in second will be returned.

• second
  Type: System.Collections.Generic.IEnumerable<TSource>
  An IEnumerable<T> whose distinct elements that also appear in the first sequence will be returned.

Return Value

Type: System.Collections.Generic.IEnumerable<TSource>
A sequence that contains the elements that form the set intersection of two sequences.

      ' 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.
      outputBlock.Text &= output.ToString() & vbCrLf

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

      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)
         outputBlock.Text += id + "\n";

      /*
       This code produces the following output:

       26
       30
      */

Public Class Product
    Implements IEquatable(Of Product)

    Public Property Name As String
    Public Property Code As Integer

    Public Function Equals1(
        ByVal other As Product
        ) As Boolean Implements IEquatable(Of Product).Equals

        ' Check whether the compared object is null.
        If other Is Nothing Then Return False

        ' Check whether the compared object references the same data.
        If Me Is Other Then Return True

        ' Check whether the products' properties are equal.
        Return Code.Equals(other.Code) AndAlso Name.Equals(other.Name)
    End Function

    Public Overrides Function GetHashCode() As Integer

        ' Get hash code for the Name field if it is not null.
        Dim hashProductName = If(Name Is Nothing, 0, Name.GetHashCode())

        ' Get hash code for the Code field.
        Dim hashProductCode = Code.GetHashCode()

        ' Calculate the hash code for the product.
        Return hashProductName Xor hashProductCode
    End Function
End Class

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

    public bool Equals(Product other)
    {

        //Check whether the compared object is null.
        if (Object.ReferenceEquals(other, null)) return false;

        //Check whether the compared object references the same data.
        if (Object.ReferenceEquals(this, other)) return true;

        //Check whether the products' properties are equal.
        return Code.Equals(other.Code) && Name.Equals(other.Name);
    }

    // If Equals() returns true for a pair of objects 
    // then GetHashCode() must return the same value for these objects.

    public override int GetHashCode()
    {

        //Get hash code for the Name field if it is not null.
        int hashProductName = Name == null ? 0 : Name.GetHashCode();

        //Get hash code for the Code field.
        int hashProductCode = Code.GetHashCode();

        //Calculate the hash code for the product.
        return hashProductName ^ hashProductCode;
    }
}

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)

For Each product In duplicates
    outputBlock.Text &= product.Name & " " & product.Code.ToString() & vbCrLf
Next
' This code produces the following output:
'
' apple 9
' 

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);

foreach (var product in duplicates)
    outputBlock.Text += product.Name + " " + product.Code + "\n";

/*
    This code produces the following output:
    apple 9
*/