Re: Visual Basic 6 how to ad an icon to progect - Visual Basic Discussion Boards

Re: What programmig language should I be using in todays market?

Eddy Vluggen16-Sep-18 23:57

16-Sep-18 23:57

I prefer English.

If you want to know which programming languages are in request in your region, you simply look at job offerings. In general, if you're starting with your first, go for C#.

Bastard Programmer from Hell Suspicious | :suss:

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.

Re: What programmig language should I be using in todays market?

Richard MacCutchan17-Sep-18 0:50

Richard MacCutchan

17-Sep-18 0:50

Given your background in VB6, the logical step would be to go for VB.NET.

Re: What programmig language should I be using in todays market?

Simon_Whale17-Sep-18 2:57

Simon_Whale

17-Sep-18 2:57

I prefer to start looking at recruitment adverts in your local area and see what skills sets are requested and work from there.

Every day, thousands of innocent plants are killed by vegetarians.

Help end the violence EAT BACON

does anyone know how I could get some programming jobs going?

Member 1398247116-Sep-18 14:24

Member 13982471

16-Sep-18 14:24

I'm a mid-level visual basic 6 programmer and am looking for some work. Any suggestions would be appreciated.

Re: does anyone know how I could get some programming jobs going?

Dave Kreskowiak16-Sep-18 15:30

Dave Kreskowiak

16-Sep-18 15:30

VB6 has been dead for a long time now.

You have no choice but to update your skill set.

Asking questions is a skill
CodeProject Forum Guidelines
Google: C# How to debug code
Seriously, go read these articles.

Dave Kreskowiak

Re: does anyone know how I could get some programming jobs going?

Mycroft Holmes16-Sep-18 20:44

Mycroft Holmes

16-Sep-18 20:44

Time travel comes to mind - go back 20 years to when VB6 was still a relevant, supported product.

Alternatively you could try and locate the rare organisation that is still ~~running~~ suffering VB6 apps and offer your services to support their dinosaur. We get the odd message for support here but they are quite rare.

I'm afraid you can no longer call yourself a programmer if your skill set is limited to a dead product.

Never underestimate the power of human stupidity
RAH

Visual Basic 6 how to ad an icon to progect

Member 1398247113-Sep-18 9:08

Member 13982471

13-Sep-18 9:08

I'm using visual basic 6 and am having problems adding an icon for my project. Every time i try to add an icon to my project, i get an error. Any help would be appreciated.

Jeff

Re: Visual Basic 6 how to ad an icon to progect

Richard MacCutchan13-Sep-18 21:41

Richard MacCutchan

13-Sep-18 21:41

Member 13982471 wrote:
Every time i try to add an icon to my project, i get an error.

We cannot guess a) what you are doing to try to add it, or b) what error you get when you do whatever it is you do.

Re: Visual Basic 6 how to ad an icon to progect

Member 1398247116-Sep-18 4:18

Member 13982471

16-Sep-18 4:18

I got the icon problem fixed. Thank you all for your input.

Jeff

Re: Visual Basic 6 how to ad an icon to progect

Eddy Vluggen13-Sep-18 23:36

Eddy Vluggen

13-Sep-18 23:36

Try adding an icon that is max 32x32 pixels, and has no more than 16 colors.

Bastard Programmer from Hell Suspicious | :suss:

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.

Re: Visual Basic 6 how to ad an icon to progect

Mycroft Holmes14-Sep-18 13:56

Mycroft Holmes

14-Sep-18 13:56

And give the poor bloody thing a walking stick.

Never underestimate the power of human stupidity
RAH

Re: Visual Basic 6 how to ad an icon to progect

Eddy Vluggen14-Sep-18 23:21

Eddy Vluggen

14-Sep-18 23:21

A silver bullet may be more appropriate.

Bastard Programmer from Hell Suspicious | :suss:

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.

Please fix my code!

toffee_paul13-Sep-18 4:36

toffee_paul

13-Sep-18 4:36

Hi, I have the following code which was posted online by a user on another forum under the MIT licence. It's a custom control which is intended to replace the rather limited FolderBrowserDialog control. It works very well with the exception of one problem as far as I can see. It won't let me specify the InitialFolder property or DefaulyFolder property without throwing a really complex looking error.
Here's the code...

Imports System
Imports System.IO
Imports System.Runtime.CompilerServices
Imports System.Runtime.InteropServices
Imports System.Windows.Forms

Public Class OpenFolderDialog
Implements IDisposable

' Gets/sets folder in which dialog will be open.
Public Property InitialFolder() As String
Get
    Return m_InitialFolder
End Get
Set(ByVal value As String)
    m_InitialFolder = value
End Set
End Property
Private m_InitialFolder As String

' Gets/sets directory in which dialog will be open if there is no recent directory available.
Public Property DefaultFolder() As String
Get
    Return m_DefaultFolder
End Get
Set(ByVal value As String)
    m_DefaultFolder = value
End Set
End Property
Private m_DefaultFolder As String

' Gets selected folder.
Public Property Folder() As String
Get
    Return m_Folder
End Get
Private Set(ByVal value As String)
    m_Folder = value
End Set
End Property
Private m_Folder As String

Public Function ShowDialog(ByVal owner As IWin32Window) As DialogResult
If Environment.OSVersion.Version.Major >= 6 Then
    Return ShowVistaDialog(owner)
Else
    Return ShowLegacyDialog(owner)
End If
End Function

Private Function ShowVistaDialog(ByVal owner As IWin32Window) As DialogResult
Dim frm = DirectCast(New NativeMethods.FileOpenDialogRCW(), NativeMethods.IFileDialog)
Dim options As UInteger
frm.GetOptions(options)
options = options Or NativeMethods.FOS_PICKFOLDERS Or NativeMethods.FOS_FORCEFILESYSTEM Or NativeMethods.FOS_NOVALIDATE Or NativeMethods.FOS_NOTESTFILECREATE Or NativeMethods.FOS_DONTADDTORECENT
frm.SetOptions(options)
If Me.InitialFolder IsNot Nothing Then
    Dim directoryShellItem As NativeMethods.IShellItem
    Dim riid = New Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE")
    'IShellItem
    If NativeMethods.SHCreateItemFromParsingName(Me.InitialFolder, IntPtr.Zero, riid, directoryShellItem) = NativeMethods.S_OK Then
        frm.SetFolder(directoryShellItem)
    End If
End If
If Me.DefaultFolder IsNot Nothing Then
    Dim directoryShellItem As NativeMethods.IShellItem
    Dim riid = New Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE")
    'IShellItem
    If NativeMethods.SHCreateItemFromParsingName(Me.DefaultFolder, IntPtr.Zero, riid, directoryShellItem) = NativeMethods.S_OK Then
        frm.SetDefaultFolder(directoryShellItem)
    End If
End If

If frm.Show(owner.Handle) = NativeMethods.S_OK Then
    Dim shellItem As NativeMethods.IShellItem
    If frm.GetResult(shellItem) = NativeMethods.S_OK Then
        Dim pszString As IntPtr
        If shellItem.GetDisplayName(NativeMethods.SIGDN_FILESYSPATH, pszString) = NativeMethods.S_OK Then
            If pszString <> IntPtr.Zero Then
                Try
                    Me.Folder = Marshal.PtrToStringAuto(pszString)
                    Return DialogResult.OK
                Finally
                    Marshal.FreeCoTaskMem(pszString)
                End Try
            End If
        End If
    End If
End If
Return DialogResult.Cancel
End Function

Private Function ShowLegacyDialog(ByVal owner As IWin32Window) As DialogResult
Using frm = New SaveFileDialog()
    frm.CheckFileExists = False
    frm.CheckPathExists = True
    frm.CreatePrompt = False
    frm.Filter = "|" & Guid.Empty.ToString()
    frm.FileName = "any"
    If Me.InitialFolder IsNot Nothing Then
        frm.InitialDirectory = Me.InitialFolder
    End If
    frm.OverwritePrompt = False
    frm.Title = "Select Folder"
    frm.ValidateNames = False
    If frm.ShowDialog(owner) = DialogResult.OK Then
        Me.Folder = Path.GetDirectoryName(frm.FileName)
        Return DialogResult.OK
    Else
        Return DialogResult.Cancel
    End If
End Using
End Function

Public Sub Dispose() Implements IDisposable.Dispose
End Sub
'just to have possibility of Using statement.
End Class

Friend Module NativeMethods

#Region "Constants"

Public Const FOS_PICKFOLDERS As UInteger = &H20
Public Const FOS_FORCEFILESYSTEM As UInteger = &H40
Public Const FOS_NOVALIDATE As UInteger = &H100
Public Const FOS_NOTESTFILECREATE As UInteger = &H10000
Public Const FOS_DONTADDTORECENT As UInteger = &H2000000

Public Const S_OK As UInteger = &H0

Public Const SIGDN_FILESYSPATH As UInteger = &H80058000UI

#End Region

#Region "COM"

<ComImport(), ClassInterface(ClassInterfaceType.None), TypeLibType(TypeLibTypeFlags.FCanCreate), Guid("DC1C5A9C-E88A-4DDE-A5A1-60F82A20AEF7")>
Friend Class FileOpenDialogRCW
End Class


<ComImport(), Guid("42F85136-DB7E-439C-85F1-E4075D135FC8"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)>
Friend Interface IFileDialog
<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
<PreserveSig()>
Function Show(<[In](), [Optional]()> ByVal hwndOwner As IntPtr) As UInteger
'IModalWindow 

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetFileTypes(<[In]()> ByVal cFileTypes As UInteger, <[In](), MarshalAs(UnmanagedType.LPArray)> ByVal rgFilterSpec As IntPtr) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetFileTypeIndex(<[In]()> ByVal iFileType As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetFileTypeIndex(ByRef piFileType As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function Advise(<[In](), MarshalAs(UnmanagedType.[Interface])> ByVal pfde As IntPtr, ByRef pdwCookie As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function Unadvise(<[In]()> ByVal dwCookie As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetOptions(<[In]()> ByVal fos As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetOptions(ByRef fos As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Sub SetDefaultFolder(<[In](), MarshalAs(UnmanagedType.[Interface])> ByVal psi As IShellItem)

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetFolder(<[In](), MarshalAs(UnmanagedType.[Interface])> ByVal psi As IShellItem) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetFolder(<MarshalAs(UnmanagedType.[Interface])> ByRef ppsi As IShellItem) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetCurrentSelection(<MarshalAs(UnmanagedType.[Interface])> ByRef ppsi As IShellItem) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetFileName(<[In](), MarshalAs(UnmanagedType.LPWStr)> ByVal pszName As String) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetFileName(<MarshalAs(UnmanagedType.LPWStr)> ByRef pszName As String) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetTitle(<[In](), MarshalAs(UnmanagedType.LPWStr)> ByVal pszTitle As String) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetOkButtonLabel(<[In](), MarshalAs(UnmanagedType.LPWStr)> ByVal pszText As String) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetFileNameLabel(<[In](), MarshalAs(UnmanagedType.LPWStr)> ByVal pszLabel As String) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetResult(<MarshalAs(UnmanagedType.[Interface])> ByRef ppsi As IShellItem) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function AddPlace(<[In](), MarshalAs(UnmanagedType.[Interface])> ByVal psi As IShellItem, ByVal fdap As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetDefaultExtension(<[In](), MarshalAs(UnmanagedType.LPWStr)> ByVal pszDefaultExtension As String) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function Close(<MarshalAs(UnmanagedType.[Error])> ByVal hr As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetClientGuid(<[In]()> ByRef guid As Guid) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function ClearClientData() As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function SetFilter(<MarshalAs(UnmanagedType.[Interface])> ByVal pFilter As IntPtr) As UInteger
End Interface

<ComImport(), Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)>
Friend Interface IShellItem
<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function BindToHandler(<[In]()> ByVal pbc As IntPtr, <[In]()> ByRef rbhid As Guid, <[In]()> ByRef riid As Guid, <Out(), MarshalAs(UnmanagedType.[Interface])> ByRef ppvOut As IntPtr) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetParent(<MarshalAs(UnmanagedType.[Interface])> ByRef ppsi As IShellItem) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetDisplayName(<[In]()> ByVal sigdnName As UInteger, ByRef ppszName As IntPtr) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function GetAttributes(<[In]()> ByVal sfgaoMask As UInteger, ByRef psfgaoAttribs As UInteger) As UInteger

<MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)>
Function Compare(<[In](), MarshalAs(UnmanagedType.[Interface])> ByVal psi As IShellItem, <[In]()> ByVal hint As UInteger, ByRef piOrder As Integer) As UInteger
End Interface

#End Region

<DllImport("shell32.dll", CharSet:=CharSet.Unicode, PreserveSig:=False)>
Public Function SHCreateItemFromParsingName(
 <MarshalAs(UnmanagedType.LPWStr)> ByVal pszPath As String,
 ByVal pbc As IntPtr,
 <MarshalAs(UnmanagedType.LPStruct)> ByVal riid As Guid,
 <MarshalAs(UnmanagedType.Interface, IidParameterIndex:=2)> ByRef ppv As IShellItem) As Integer
End Function
End Module

Here's how to call a new instance...

Using frm = New OpenFolderDialog()
frm.InitialFolder = "E:\"
frm.DefaultFolder = "E:\"
If frm.ShowDialog(Me) = DialogResult.OK Then
    MessageBox.Show(Me, frm.Folder)
End If
End Using

This is the exception error I'm getting...

WindowsApplication1.NativeMethods::SHCreateItemFromParsingName' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.'

Many thanks.

Re: Please fix my code!

Dave Kreskowiak14-Sep-18 6:34

Dave Kreskowiak

14-Sep-18 6:34

You're going to have to go back to the person who wrote that code and ask him/her. I don't have the time to dig into this.

An unbalanced stack is usually caused by parameter types being declared and passed incorrectly from what Windows expects. Specifically, the problem is going to be rooted in this line:

VB.NET

<DllImport("shell32.dll", CharSet:=CharSet.Unicode, PreserveSig:=False)>
Public Function SHCreateItemFromParsingName(
 <MarshalAs(UnmanagedType.LPWStr)> ByVal pszPath As String,
 ByVal pbc As IntPtr,
 <MarshalAs(UnmanagedType.LPStruct)> ByVal riid As Guid,
 <MarshalAs(UnmanagedType.Interface, IidParameterIndex:=2)> ByRef ppv As IShellItem) As Integer
End Function

Asking questions is a skill
CodeProject Forum Guidelines
Google: C# How to debug code
Seriously, go read these articles.

Dave Kreskowiak

Re: Please fix my code!

Eddy Vluggen14-Sep-18 23:32

Eddy Vluggen

14-Sep-18 23:32

pinvoke.net: SHCreateItemFromParsingName (shell32)[^]

The example there does not have the "As Integer" part at the end of the declaration.

Bastard Programmer from Hell Suspicious | :suss:

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.

Re: Please fix my code!

Richard Deeming18-Sep-18 3:38

Richard Deeming

18-Sep-18 3:38

That looks like a mistake - the official documentation says it returns an HRESULT:
SHCreateItemFromParsingName function | Microsoft Docs[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Re: Please fix my code!

Eddy Vluggen18-Sep-18 5:05

Eddy Vluggen

18-Sep-18 5:05

Good catch Smile | :)

Bastard Programmer from Hell Suspicious | :suss:

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.

Open / Display SVG images within Visual Basic 6

davesmithmiap13-Sep-18 1:19

davesmithmiap

13-Sep-18 1:19

Hi
I am trying to find a way of displaying SVG within Visual Basic 6, you could at one point use Adobe Viewer 3 - but not longer.

I have managed to self create a HTML page, launch the assocaited web browser to show it, then i capture the screen - however the screen is captured but without the image being shown on it, yet the image is on the web page, if i do a normal screen capture - i can get the image.

All i am actually looking to do is to show the svg image within our vb application - which sadly it is written in vb6 and is far too big to change over.

I have looked into the SVG and in theroy could write an XML parser to read in and display but it makes sense to use the inbuilt browser control as they get updated.

Any suggestions ?

Re: Open / Display SVG images within Visual Basic 6

Richard Deeming13-Sep-18 2:33

Richard Deeming

13-Sep-18 2:33

The web browser control uses Internet Explorer. By default, it's stuck in IE7 mode unless you change the registry on every computer that runs your application:
Web Browser Control & Specifying the IE Version - Rick Strahl's Web Log[^]

IE didn't add support for SVG until v8:
Can I use... Support tables for HTML5, CSS3, etc[^] (Click "Show all" to see the old versions.)

Even if you can force the control to use the latest rendering mode, you may still need some workarounds for the bugs:
Test Scaling Of SVG Images In Fluid Layouts[^]

Do you need to resize the SVG image? If not, it would make more sense to convert it to an image format that VB6 supports.

NB: VB6 has been "dead" for almost two decades now. Whilst the application will still work, you'll struggle to support any new API or technology created in this millennium, and you'll find it increasingly difficult to get help for any issues. It may be time to re-evaluate the "too big to change" decision. Smile | :)

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Re: Open / Display SVG images within Visual Basic 6

Member 1396504228-Sep-18 3:15

Member 13965042

28-Sep-18 3:15

Hi,
support for *.svg-files is quite limited on Windows operating systems. So while I would normally advise to keep your vb6 code free of dependencies, in this case it is not possible to do without. However, since you are using a "real" programming language such as vb6 Big Grin | :-D

, you're in luck:
Have a look at Avax Vector ActiveX (OCX)
This library will add a lot more than just *.svg support and you'll find proper vb6 example code on the page - so you should be up and running within an hour.

Another approach, depending on how much effort you want to invest, would be to use the vbRichClient-Framework which uses cairo as a forms rendering engine: *.svg loading and saving is build right in and vbRichClient.dll is a rather well-performing and light-weight library - and since you'll have to distribute vbrun.dll anyway...

Btw. I wouldn't pay any notice to people trying to get you to "migrate" you to a "up-to-date platform". Chances are, these folks have never used vb6 anyway - and thus don't know how it has envolved in the last 20 years. As long as Windows is based mostly on COM, any managed code will look very poor indeed when compared to vb6.

Re: Open / Display SVG images within Visual Basic 6

Richard Deeming28-Sep-18 4:38

Richard Deeming

28-Sep-18 4:38

Linking to commercial products is spam, and will not be tolerated. Your "Avax Vector ActiveX" library costs $380.

wrote:
Chances are, these folks have never used vb6 anyway - and thus don't know how it has envolved in the last 20 years.

You know what they say about assumptions. Lots of us have suffered through using VB6 back when it was an active language. And it has been officially dead for almost 20 years, so it won't have "evolved" much. D'Oh! | :doh:

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Re: Open / Display SVG images within Visual Basic 6

Darrell Hagan 202113-Jun-21 12:53

Darrell Hagan 2021

13-Jun-21 12:53

Phooey. VB6 was and still is by far a better programming tool than any of that bloated and messy .NET crap.....

Could someone explain why For Each and For Next loops behave differently with lists?

MattiasW768-Sep-18 14:13

MattiasW76

8-Sep-18 14:13

Hi everyone.
I think this might be my first post here. I rarely post questions, normally I like to search for my answers but this I thought I try to ask here.

Anyway, I noticed something that I found strange while using lists and For loops.

I'm pasting an example code here:
What it does is trying to scale rectangles saved within a list using loops.

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
        With rect
            rect = New Rectangle(CInt(.Left * gScale), CInt(.Top * gScale),
                                 CInt(.Width * gScale), CInt(.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}", .Left, .Top, .Width, .Height)
        End With
    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
        With lstRectangles(i)
            lstRectangles(i) = New Rectangle(CInt(.Left * gScale), CInt(.Top * gScale),
                                             CInt(.Width * gScale), CInt(.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}", .Left, .Top, .Width, .Height)
        End With
    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, lstRectangles As List(Of Rectangle))
    For Each rect As Rectangle In lstRectangles
        With rect
            Debug.WriteLine("{0}{1}x{2},{3}x{4}", sText, CStr(.Left), CStr(.Top), CStr(.Width), CStr(.Height))
        End With
    Next
End Sub

This produces this result in the debug window:

Before scaling:               100x200,1000x2000
Before scaling:               500x700,1500x2000

Result inside For Each Loop:  10x20,100x200
Result inside For Each Loop:  50x70,150x200
Result outside For Each Loop: 100x200,1000x2000
Result outside For Each Loop: 500x700,1500x2000

Result inside For Next Loop:  100x200,1000x2000
Result inside For Next Loop:  500x700,1500x2000
Result outside For Next Loop: 10x20,100x200
Result outside For Next Loop: 50x70,150x200

As you can see, while being on the inside of a for each loop the changes to the elements is readable and reusable. But when getting on the outside it is clear that none of the changes got saved back to the list.

However, when using the traditional For Next loop, no changes can be seen to the list until you get to the outside. This is the opposite behaviour. Confused | :confused:

This just feels weird and forces me to copy the value when I want to do more advanced calculations and the write it back to the item after. And as far as I can see the Inumerable loop seems worthless when wanting to write data back..

Am I doing something wrong or is there a logic to this?

[Edited a typo..]

modified 9-Sep-18 7:09am.

Re: Could someone explain why For Each and For Next loops behave differently with lists?

Eddy Vluggen8-Sep-18 23:51

Eddy Vluggen

8-Sep-18 23:51

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.

Imagine a for-next to make a copy of the list; if you have reference-type objects in there (objects), then you can modify the properties of the object (only the pointer to object is readonly, not its properties). That doesn't work for value-types.

Use an object instead of a Rectangle, and things will work as you expected. If you want to keep using Rectangle (which is cheaper in terms of resource-usage) you'd limit yourself to For..Next loops.

Bastard Programmer from Hell Suspicious | :suss:

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.

Re: Could someone explain why For Each and For Next loops behave differently with lists?

MattiasW769-Sep-18 1:04

MattiasW76

9-Sep-18 1:04

Oh great..

I fell for the byval mistake... again. D'Oh! | :doh:

Of course that's why the elements was a copy. I was so sure this had worked before but obviously with reference objects.

Thank's for pointing this out, Eddy! Thumbs Up | :thumbsup:

I should have realised this but when it failed me I just switched to a For..Next loop and ran into the next problem.
Changes to the lists elements is not visible until you exit the loop.

Dare I ask why this is?

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