Imports System
' ------------------------------------------------------------
' generic_swap
' ------------------------------------------------------------
' A fully generic VB.NET swap function implemented using generics.
'
' Parameters:
' a, b - variables passed ByRef so their values can be swapped
'
' This function uses a temporary variable and assignment, which is the
' idiomatic and type‑safe way to swap objects in VB.NET. It works for:
' - built‑in types (Integer, Double, etc.)
' - String
' - Structures / Classes
' - user‑defined types
' ------------------------------------------------------------
Module SwapUtils
Public Sub GenericSwap(Of T)(ByRef a As T, ByRef b As T)
Dim temp As T = a
a = b
b = temp
End Sub
End Module
' ------------------------------------------------------------
' VB.NET equivalent of the C++ struct Point
' ------------------------------------------------------------
Structure Point
Public X As Integer
Public Y As Integer
Public Sub New(x As Integer, y As Integer)
Me.X = x
Me.Y = y
End Sub
Public Overrides Function ToString() As String
Return "(" & X & "," & Y & ")"
End Function
End Structure
' ------------------------------------------------------------
' Print arrays of integers
' ------------------------------------------------------------
Module Utils
Public Sub PrintIntArray(arr As Integer())
For Each v In arr
Console.Write(v & " ")
Next
Console.WriteLine()
End Sub
End Module
Module Program
Sub Main()
Console.WriteLine("=== TEST 1: Swap integers ===")
Dim x As Integer = 10
Dim y As Integer = 20
Console.WriteLine("Before: x=" & x & ", y=" & y)
SwapUtils.GenericSwap(x, y)
Console.WriteLine("After: x=" & x & ", y=" & y & Environment.NewLine)
Console.WriteLine("=== TEST 2: Swap doubles ===")
Dim a As Double = 3.14
Dim b As Double = 2.71
Console.WriteLine("Before: a=" & a & ", b=" & b)
SwapUtils.GenericSwap(a, b)
Console.WriteLine("After: a=" & a & ", b=" & b & Environment.NewLine)
Console.WriteLine("=== TEST 3: Swap structs ===")
Dim p1 As New Point(1, 2)
Dim p2 As New Point(9, 8)
Console.WriteLine("Before: p1=" & p1.ToString() & ", p2=" & p2.ToString())
SwapUtils.GenericSwap(p1, p2)
Console.WriteLine("After: p1=" & p1.ToString() & ", p2=" & p2.ToString() & Environment.NewLine)
Console.WriteLine("=== TEST 4: Swap array elements ===")
Dim arr As Integer() = {1, 2, 3, 4, 5}
Console.Write("Before: ")
Utils.PrintIntArray(arr)
SwapUtils.GenericSwap(arr(1), arr(3))
Console.Write("After: ")
Utils.PrintIntArray(arr)
Console.WriteLine()
Console.WriteLine("=== TEST 5: Swap strings ===")
Dim str1 As String = "Hello"
Dim str2 As String = "World"
Console.WriteLine("Before: str1=""" & str1 & """, str2=""" & str2 & """")
SwapUtils.GenericSwap(str1, str2)
Console.WriteLine("After: str1=""" & str1 & """, str2=""" & str2 & """" & Environment.NewLine)
End Sub
End Module
' ------------------------------------------------------------
' run:
'
' === TEST 1: Swap integers ===
' Before: x=10, y=20
' After: x=20, y=10
'
' === TEST 2: Swap doubles ===
' Before: a=3.14, b=2.71
' After: a=2.71, b=3.14
'
' === TEST 3: Swap structs ===
' Before: p1=(1,2), p2=(9,8)
' After: p1=(9,8), p2=(1,2)
'
' === TEST 4: Swap array elements ===
' Before: 1 2 3 4 5
' After: 1 4 3 2 5
'
' === TEST 5: Swap strings ===
' Before: str1="Hello", str2="World"
' After: str1="World", str2="Hello"
' ------------------------------------------------------------
