Translating fixed to VB

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Hello everyone, I'm translating a library from C# to vb.net, it's a complex job due to the many differences but it's almost done. The only point where I can't is the following:

var CurrentWord = new StringBuilder();
char[] Buff = Text.ToCharArray();
fixed (char* c = &Buff[0])

especially "fixed (char* c = &Buff[0])".

I understand that vb.net does not have compatible in-memory pointers but I hope there is a solution even if it is convoluted.

Thank you all

Excuse my English as always...

What I have tried:

I tried converting with "https://converter.telerik.com/" and others but without success, System.NotSupportedException: UnsafeKeyword is not supported!

Posted 15-Jan-24 4:54am

10071962

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Dave Kreskowiak 15-Jan-24 11:19am

The first question is why are you converting the C# library at all when you can just add a reference to it in VB.NET and use the existing library?

10071962 15-Jan-24 11:26am

Because having the source in VB I can modify it and integrate it into my project which is a cryptographic editor and I am interested in some functions of this library that you find here. https://code.google.com/archive/p/alsing/downloads

Dave Kreskowiak 15-Jan-24 12:27pm

OK, the problem is there is no Vb.NET equivalent. An idea would be to create a C# class library wrapping the functionality of allocating buffers and having "fixed" access to them, then reference that library in VB.NET.

No, I don't have examples of doing such. I just abandoned VB.NET entirely and went with C# for all my .NET development needs.

10071962 16-Jan-24 0:29am

Thanks, I tried all your suggestions but without success; the closest one is "https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/strings/how-to-access-characters-in-strings" , but this isn't functional either. Dave Kreskowiak, I don't quite understand what you mean. Thank you all.

Jo_vb.net 15-Jan-24 12:40pm

Perhaps this helps you
https://stackoverflow.com/questions/44976633/convert-fixed-and-byte-from-c-sharp-to-vb-net

10071962 16-Jan-24 0:29am

Thanks, I tried all your suggestions but without success; the closest one is "https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/strings/how-to-access-characters-in-strings" , but this isn't functional either. Dave Kreskowiak, I don't quite understand what you mean. Thank you all.

[no name] 15-Jan-24 18:25pm

https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/strings/how-to-access-characters-in-strings

10071962 16-Jan-24 0:29am

Thanks, I tried all your suggestions but without success; the closest one is "https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/strings/how-to-access-characters-in-strings" , but this isn't functional either. Dave Kreskowiak, I don't quite understand what you mean. Thank you all.

10071962 16-Jan-24 2:33am

What do you think of this solution? It might work? I can't really try it yet.

Dim Buff() As Char = Text.ToCharArray
Dim c() As Char
Dim obj As Object = Buff
Dim gh As Runtime.InteropServices.GCHandle = Runtime.InteropServices.GCHandle.Alloc(obj, Runtime.InteropServices.GCHandleType.Pinned)
Dim ip As IntPtr = gh.AddrOfPinnedObject()
Runtime.InteropServices.Marshal.Copy(Buff, 0, ip, 4)
c = Buff
gh.Free()

See: "https://www.c-sharpcorner.com/forums/c-sharp-to-vb-net-conversion-byte-pointers-etc"

Thank you

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Maciej Los · Answer 1 · 2024-01-16T09:25:00

Solution 2

I'd suggest to read this excellent article: How to do pointers in Visual Basic[^]
These can be helpful too:
Pointers in Visual Basic using Undocumented Functions[^]
Pointers and Unmanaged Memory Handling in VB.NET | BinaryIntellect Knowledge Base[^]

Posted 16-Jan-24 9:25am

Maciej Los

Updated 16-Jan-24 9:27am

v2

Graeme_Grant · Answer 2 · 2024-01-16T12:38:00

Quote:
I tried converting with "https://converter.telerik.com/" and others but without success, System.NotSupportedException: UnsafeKeyword is not supported!

Most of these are not well maintained or simply abandoned. What I find, as a better solution, not just for C# <-> VB, but any <-> any, is AOpen's ChatGPT[^]. When in a pinch, I find that it is very good at converting code.

Here is how to ask:

Convert the following C# to VB.NET:

var CurrentWord = new StringBuilder();
char[] Buff = Text.ToCharArray();
fixed (char* c = &Buff[0])

And it will give you an answer. But note: while it is very good at conversion, it's not the best at taking a statement and converting to code. Often, more than not, you will have to either ask it more questions, debug and modify the code that it gives you, or simply abandon and write it yourself.

Jens Eckervogt · Answer 3 · 2024-01-18T00:00:00

Solution 4

If I suggest you to fix like char* from string.

But I have already 2 different sbyte* and byte* formats from string. And I will release soon char* for Windows Users of WinAPI.

Check out my article!
If you use VB than you can use DeafMan1983.Conversion. But I am not sure for latest version of net 7.x or 8.x.

I hope you get my solution.

Posted 18-Jan-24 0:00am

Jens Eckervogt

Comments

10071962 18-Jan-24 8:24am

Thank you very much!

Jens Madsen, Højby · Answer 4 · 2024-04-24T06:55:00

Solution 5

Fixed: To get a pointer to the first char (or whatever), use
'Marshal.UnsafeAddrOfPinnedArrayElement(Buff, 0)'

I believe that using GCHandle to pin 'Buff' isn't needed on a local variable,
but you'd better check it!;)

Posted 2 days ago

Jens Madsen, Højby

Translating fixed to VB

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