Mega Code Archive
Enumerable Except produces the set difference of two sequences by using IEqualityComparer(Of T)
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Imports System
Imports System.Linq
Imports System.Collections.Generic
Public Class Item
Public Property Name As String
Public Property Code As Integer
End Class
Public Class ItemComparer
Implements IEqualityComparer(Of Item)
Public Function Equals1(ByVal x As Item, ByVal y As Item) As Boolean Implements IEqualityComparer(Of Item).Equals
If x Is y Then Return True
If x Is Nothing OrElse y Is Nothing Then Return False
Return (x.Code = y.Code) AndAlso (x.Name = y.Name)
End Function
Public Function GetHashCode1(ByVal product As Item) As Integer Implements IEqualityComparer(Of Item).GetHashCode
If product Is Nothing Then Return 0
Dim hashItemName = If(product.Name Is Nothing, 0, product.Name.GetHashCode())
Dim hashItemCode = product.Code.GetHashCode()
Return hashItemName Xor hashItemCode
End Function
End Class
Public Class Example
Public Shared Sub Main()
Dim fruits1() As Item =
{New Item With {.Name = "apple", .Code = 9},
New Item With {.Name = "orange", .Code = 4},
New Item With {.Name = "lemon", .Code = 12}}
Dim fruits2() As Item =
{New Item With {.Name = "apple", .Code = 9}}
' Get all the elements from the first array
' except for the elements from the second array.
Dim except = fruits1.Except(fruits2, New ItemComparer())
For Each product In except
Console.WriteLine(product.Name & " " & product.Code)
Next
End Sub
End Class
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