Enumerable.Union<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 form the first set for the union.

• second
  Type: System.Collections.Generic.IEnumerable<TSource>
  An IEnumerable<T> whose distinct elements form the second set for the union.

Return Value

Type: System.Collections.Generic.IEnumerable<TSource>
An IEnumerable<T> that contains the elements from both input sequences, excluding duplicates.

      ' Create two arrays of integer values.
      Dim ints1() As Integer = {5, 3, 9, 7, 5, 9, 3, 7}
      Dim ints2() As Integer = {8, 3, 6, 4, 4, 9, 1, 0}

      ' Get the set union of the two arrays.
      Dim union As IEnumerable(Of Integer) = ints1.Union(ints2)

      ' Display the resulting set's values.
      Dim output As New System.Text.StringBuilder
      For Each num As Integer In union
         output.AppendLine(num & " ")
      Next
      outputBlock.Text &= output.ToString() & vbCrLf

      ' This code produces the following output:
      '
      ' 5 
      ' 3 
      ' 9 
      ' 7 
      ' 8 
      ' 6 
      ' 4 
      ' 1 
      ' 0 

      int[] ints1 = { 5, 3, 9, 7, 5, 9, 3, 7 };
      int[] ints2 = { 8, 3, 6, 4, 4, 9, 1, 0 };

      IEnumerable<int> union = ints1.Union(ints2);

      foreach (int num in union)
      {
         outputBlock.Text += String.Format("{0} ", num);
      }

      /*
       This code produces the following output:

       5 3 9 7 8 6 4 1 0
      */

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 both arrays
' excluding duplicates.
Dim union = store1.Union(store2)

For Each product In union
    outputBlock.Text &= product.Name & " " & product.Code.ToString() & vbCrLf
Next
' This code produces the following output:
'
' apple 9
' orange 4
' lemon 12
' 

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 both arrays
//excluding duplicates.

IEnumerable<Product> union =
  store1.Union(store2);

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

/*
    This code produces the following output:

    apple 9
    orange 4
    lemon 12
*/