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Visual Basic CopyMemory Problem


In my line of work, I have to deal with several file formats that contain fixed length records. Dim S As String, Buffer As String, ptr As Long Buffer = String(100, vbNullChar) ptr = StrPtr(Buffer) ' Copy string to Buffer S = "abcd" CopyMemory ByVal ptr, ByVal S, Len(S) Application Lifecycle> Running a Business Sales / Marketing Collaboration / Beta Testing Work Issues Design and Architecture ASP.NET JavaScript C / C++ / MFC> ATL / WTL / STL Managed C++/CLI In some cases, perhaps that's a good thing. http://simplecoverage.org/visual-basic/visual-basic-problem.php

This is often an indication that other memory is corrupt. #region API [DllImport("Kernel32.dll", EntryPoint = "RtlMoveMemory")] private static extern void CopyMemory(IntPtr Destination, IntPtr Source, [MarshalAs(UnmanagedType.U4)] uint Length); #endregionIntPtr ipSource = m_bmdLogo.Scan0; Right. Click the Open button. Registration on or use of this site constitutes acceptance of our Privacy Policy. click resources

Copymemory Vba

you may use strconv to convert string into byte array. I am not a C++ or C# programmer so reading the documentation is throwing me a little. Reply With Quote Sep 15th, 2007,09:05 PM #4 Milk View Profile View Forum Posts Cumbrian Join Date Jan 2007 Location 0xDEADBEEF Posts 2,448 Re: CopyMemory Problem (Simple) Whats wrong with Picture2.picture Reply With Quote June 19th, 2007,03:13 PM #3 sbhan View Profile View Forum Posts Junior Member Join Date Jun 2007 Posts 3 Re: CopyMemory Problem Hi WizBang, thanks for the reply!

Now, after some tweaks CopyMemory works, but there's another problem - I don't know why it works ;). Peterso#13 / 15 CopyMemory problem Hi Jerry -- Quote:> >Using that technique causes undo overhead in many cases, and the potential of > >corruption in others. VB 6 declaration is as follows:Private Declare Sub CopyMemory Lib "kernel32" Alias _ "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long) But in .NET, most usage of CopyMemory Copymemory C++ I'd suggest that you always type your arguments whenever possible.

To deal with this problem VB programmers uses function CopyMemory to copy memory like this: Dim a As Long Dim b() As Byte ReDim b(3) CopyMemory ByVal varptr(a), ByVal varptr(b), 4 Marshal.FreeHGlobal(p_objTarget) Catch ex As System.OutOfMemoryException ' An exception could occur if the system is out of ' memory and the block of heap memory could not be ' set aside for A.G Sign In·ViewThread·Permalink No need to use P/Invoke Richard Deeming10-Mar-03 0:20 Richard Deeming10-Mar-03 0:20 You don't need to use P/Invoke to call the CopyMemory API for this. AllocHGlobal returns a pointer ' to this memory, which is needed for the next call.

The Any keyword is not a data type, like Variant; rather, it's used to let virtually any data type into the function call (it's analogous to the void keyword in C). Vb6 Copymemory Byte Array If not, then using Len() instead of LenB() would make sense. I always make a determined effort to do this, but sometimes I do miss something, or misinterpret something, and I appreciate it when this is pointed out to me - politely. I try to avoid straying from the topic at hand, so when you get to the bolded sections of code, just copy and paste them into your program.

Copymemory C#

Posting Guidelines Promoting, selling, recruiting, coursework and thesis posting is forbidden.Tek-Tips Posting Policies Jobs Jobs from Indeed What: Where: jobs by HomeForumsProgrammersLanguagesVisual Basic (Microsoft) Versions 5/6 Forum Strange CopyMemory Problem thread222-236226 https://forums.techguy.org/threads/visual-basic-copymemory-problem.696937/ Some of programmers at the higher level of knowledge can modify pointers at objects as well. Copymemory Vba For more information, see WinBase.h and WinNT.h. Copymemory Vs Memcpy System.Buffer Manipulates arrays of primitive types such as Boolean, Char, SByte, Byte, Int16, UInt16, Int32, UInt32, Int64, UInt64, IntPtr, UIntPtr, Single, and Double, and does not apply to objects.

For overlapped blocks, use the MoveMemory function. this contact form Use StrPtr() -- = > >something like this -- instead: > > ' Copy text into buffer. > > Call CopyMemory(m_Buffer(m_Len), ByVal StrPtr(NewText), = > >LenNewText) > Use the System.Runtime.InteropServices.Marshal.PtrToStructure method to copy the data from the heap memory that is pointed to by p_objTarget into the Target object. Betting that'll happen in all languages around the earth is another thing entirely. Copymemory Vb6

You have characters left. Conveniently? Visual Basic CopyMemory Problem Discussion in 'Software Development' started by CptNeutral, Mar 25, 2008. have a peek here More problems with CopyMemory! 8.

The documentation for this function is word for word as above and is only information. Movememory In the Solution Explorer, right click on the CopyMemorySample Project. (Just under the Solution in bold.) Select the 'Add' menu. In the example I posted ( CVL() and MKL$() ) the 4 'characters' become the correct 4 bytes when written to disk - using StrPtr garbage would be written to disk.

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Not necessarily with the example you posted, but yours may be more exceptional than you realize. Quote:>Hi Jerry -- >> >Using that technique causes undo overhead in many cases, and the potential of >> >corruption in others. It may work, but I would never bet on it. Rtlmovememory If this is not done, it will result in a memory leak.

After learning that VB converts its BSTR to ANSI before passing it to the DLL, I did try hdl = GlobalAlloc(GHND, Len(outputStr) + 1) ptr = GlobalLock(hdl) Call CopyMemory(ptr, outputStr, Len(outputStr)) CoughUpCookies(e) End Try ' Free resources assigned to our instance of the WINAPI class API = Nothing ' send the results back for printing Return Target End Function 'CopyStringToClass '------------ ADD The memory could not be read.") on the CopyMemory call? Check This Out Also, you may have wondered why I arbitrarily buffered strDest with 1000 space characters.

Forum New Posts FAQ Calendar Forum Actions Mark Forums Read Quick Links Today's Posts View Site Leaders What's New? Data corruption. Select 'Add Class' from the Add menu. For effective using of API calls are important operators VarPtr which returns pointer at variable specified and AddressOf which is important for callback functions.

Never a good >idea to store binary data in VB Strings (since VB4, before which it was the *only* >documented method). >> Using StrPtr avoids the ANSII copy overhead, but it Subscribe to our newsletter below. In practice parameter type Long (4 bytes) will be called ByVal, but String or complex data types will be called ByRef. If you set the quality to 100%, its still pretty fast.

That works perfectly. > ** Evaluating commands: you copy the query ("//echo $server") into a > memory-mapped file, and then SendMessage WM_USER + 201, and then again, > CopyMemory the result Hope it fixes your problem. This is why I use Char Arrays in my Class and Structure examples History Initial Article Date: 02/26/2003 License This article has no explicit license attached to it but may contain This is likely because the managed PInvoke signature does not match the unmanaged target signature.

Marshal.FreeHGlobal(p_objTarget) Catch ex As System.OutOfMemoryException ' An exception could occur if the system is out of ' memory and the block of heap memory could not be ' set aside for If in doubt please contact the author via the discussion board below.A list of licenses authors might use can be found here Share email twitter facebook linkedin reddit google+ About the Later... Reason: Added [code] tags Reply With Quote June 19th, 2007,01:40 PM #2 WizBang View Profile View Forum Posts Visit Homepage Super Moderator Power Poster Join Date Dec 2001 Posts 6,332 Re:

chem Visual Studio 6, Visual Studio.NET 2005, MASM Reply With Quote Quick Navigation Visual Basic 6 and Earlier Top Site Areas Settings Private Messages Subscriptions Who's Online Search Forums Forums Home Declare a variable of type 'WINAPI' and initialize it using the New keyword. Reply With Quote Sep 15th, 2007,10:11 PM #6 chemicalNova View Profile View Forum Posts G&G Moderator Join Date Jun 2002 Location Victoria, Australia Posts 4,246 Re: CopyMemory Problem (Simple) Theres a If you're not already familiar with forums, watch our Welcome Guide to get started.

Tue, 24 Aug 2004 20:07:30 GMT Karl E. Much clearer way how to deal with such tasks is to move code of this kind into separated dll written in C++ and call this dll.