Visual Basic

MSDN[^] states:

The Current property of the enumerator object is ReadOnly, and it returns a local copy of each collection element. This means that you cannot modify the elements themselves in a For Each...Next loop. Any modification you make affects only the local copy from Current and isn't reflected back into the underlying collection. However, if an element is a reference type, you can modify the members of the instance to which it points.

Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

MattiasW76 wrote:

Dare I ask why this is?

Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.

    Sub TestForLoop()
        ' Declare a list of rectangles and add 2 rectangles to it
        Dim lstRectangles As New List(Of Rectangle)
        lstRectangles.Add(New Rectangle(100, 200, 1000, 2000))
        lstRectangles.Add(New Rectangle(500, 700, 1500, 2000))

        ' This is the number used to scale the rectangle
        Dim gScale As Single = 0.1

        ' Before doing changes, write the rectangles dimensions to debug window.
        ShowRectDimensions("Before scaling:               ", lstRectangles)
        Debug.WriteLine("")

        ' Jump thru the elements, update and scale each rectangles dimensions. 
        For Each rect As Rectangle In lstRectangles
            rect = New Rectangle(CInt(rect.Left * gScale), CInt(rect.Top * gScale),
                                 CInt(rect.Width * gScale), CInt(rect.Height * gScale))
            ' Write the changes to debug window while looping thru the list.
            Debug.WriteLine("Result inside For Each Loop:  {0}x{1},{2}x{3}", rect.Left, rect.Top, rect.Width, rect.Height)
        Next

        ' After the loop, write the rectangles dimensions to debug window once again.
        ShowRectDimensions("Result outside For Each Loop: ", lstRectangles)
        Debug.WriteLine("")


        ' Go thru the list, update and scale each rectangles dimension. 
        For i As Integer = 0 To lstRectangles.Count - 1
            Dim rect As Rectangle = lstRectangles(i)
            lstRectangles(i) = New Rectangle(CInt(rect.Left * gScale), CInt(rect.Top * gScale),
                                                 CInt(rect.Width * gScale), CInt(rect.Height * gScale))
            ' Write the changes to debug window while looping thru the list.
            Debug.WriteLine("Result inside For Next Loop:  {0}x{1},{2}x{3}", lstRectangles(i).Left, lstRectangles(i).Top, lstRectangles(i).Width, lstRectangles(i).Height)
        Next

        ' After the loop, write the rectangles dimensions to debug window once again.
        ShowRectDimensions("Result outside For Next Loop: ", lstRectangles)
        Debug.WriteLine("")
    End Sub

    ' Created this sub to save some repetition. It writes the dimensions of the rectangles in a list.
    Private Sub ShowRectDimensions(sText As String, ByRef lstRectangles As List(Of Rectangle))
        For i As Integer = 0 To lstRectangles.Count - 1
            With lstRectangles(i)
                Debug.WriteLine("{0}{1}x{2},{3}x{4}", sText, CStr(.Left), CStr(.Top), CStr(.Width), CStr(.Height))
            End With
        Next
    End Sub

Sub TestForLoop()

    ' Declare a list of rectangles and add 3 rectangles to it
    Dim lstRectangles As New List(Of Rectangle)
    lstRectangles.Add(New Rectangle(100, 200, 1000, 2000))
    lstRectangles.Add(New Rectangle(500, 150, 500, 200))
    lstRectangles.Add(New Rectangle(500, 700, 1500, 2000))

    Dim pre, n As Integer


    Debug.WriteLine(vbCrLf & "Inside Loop:")

    ' I'm skipping the first rectangle to avoid division with zero.
    For i As Integer = 1 To lstRectangles.Count - 1
        With lstRectangles(i)

            ' Do a change to the rectangle within the with-block.
            lstRectangles(i) = New Rectangle(.Left + 10, .Top, .Width, .Height)

            ' Show Change.
            Debug.WriteLine("Rectangle " & i)
            Debug.WriteLine("    1st result, Direct Call: {0}  -  With-block: {1}  -  (Added:
                           10)", lstRectangles(i).Left, .Left)

            ' Do calculations based on values from previous rectangles.
            n = lstRectangles(i - 1).Left / i

            ' Do a new change to the rectangle based on calulations and still within the same with-block.
            lstRectangles(i) = New Rectangle(.Left + n, .Top, .Width, .Height)

            ' Show new change.
            Debug.WriteLine("New result, Direct Call: {0}  -  With-block: {1}  -  (Added:
                           {2})", lstRectangles(i).Left, .Left, n)
        End With
    Next

    Debug.WriteLine(vbCrLf & "Outside Loop:")

    For i As Integer = 1 To lstRectangles.Count - 1
        With lstRectangles(i)
            Debug.WriteLine("Result: ({0}x{1}, {2}x{3})", .Left, .Top, .Width, .Height)
        End With
    Next

End Sub

Inside Loop:
Rectangle 1
  1st result, Direct Call: 510  -  With-block: 500  -  (Added: 10)
  New result, Direct Call: 600  -  With-block: 500  -  (Added: 100)
Rectangle 2
  1st result, Direct Call: 510  -  With-block: 500  -  (Added: 10)
  New result, Direct Call: 800  -  With-block: 500  -  (Added: 300)

Outside Loop:
Result: (600x150, 500x200)
Result: (800x700, 1500x2000)

Quote:

You need to add a reference to the System.Web.Helpers assembly, and add Imports System.Web.Helpers to the top of your code file.

Private Sub CreateAccount(ByVal username As String, ByVal password As String, ByVal email As String)
    Dim hashedPassword As String = Crypto.HashPassword(password)
    
    Using connection As New OleDbConnection("... YOUR CONNECTION STRING HERE ...")
        Using cmd As New OleDbCommand("INSERT INTO university (username, strEmail, hashed) VALUES (@username, @strEmail, @hashed)", connection)
            cmd.Parameters.AddWithValue("@username", username)
            cmd.Parameters.AddWithValue("@strEmail", email)
            cmd.Parameters.AddWithValue("@hashed", hashedPassword)
            
            connection.Open()
            cmd.ExecuteNonQuery()
        End Using
    End Using
End Sub

Private Sub BtnReg_Click(sender As Object, e As EventArgs) Handles BtnReg.Click
    CreateAccount(username.Text, password.Text, strEmail.Text)
End Sub

<compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
  <application>
    <!-- A list of the Windows versions that this application has been tested on and is
         is designed to work with. Uncomment the appropriate elements and Windows will
         automatically selected the most compatible environment. -->

    <!-- Windows Vista -->
    <supportedOS Id="{e2011457-1546-43c5-a5fe-008deee3d3f0}" />

    <!-- Windows 7 -->
    <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}" />

    <!-- Windows 8 -->
    <supportedOS Id="{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}" />

    <!-- Windows 8.1 -->
    <supportedOS Id="{1f676c76-80e1-4239-95bb-83d0f6d0da78}" />

    <!-- Windows 10 -->
    <supportedOS Id="{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />

  </application>
</compatibility>

Module Module1

    Sub Main()
        Dim iCount As Integer
        Dim strToSearch As String = "Every instance. Replace() will inteiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiirnally loop throughiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii the entire source string. It replaces all occurrences of the substring you want to replace. Tip: This behavior is useful when dealing with common string replacements in programs.  But: If you do not understand this behavior you may end up writing inefficient code that has unneeded loops. "
        Dim strSearchFor As String = "i"
        Console.WriteLine(strToSearch)
        iCount = strToSearch.Length() - strToSearch.Replace(strSearchFor, "").Length
        Console.WriteLine("There are " + iCount.ToString() + " letter " + strSearchFor + "'s in the string")

    End Sub

End Module