 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
.NET Forum / .NET Framework / Interop / September 2006Get length of IntPtr in bytes?
I am using Interop with a C++ function which returns a pointer to an array of bytes. I'm using an IntPtr and Marshal.Copy to populate a managed array of bytes in C#, however I don't know the size I need to allocate to the array. Is there any way of calculating the size of the memory IntPtr is pointing to in bytes? If not, is there an alternative way of accomplishing this? Should I be using IntPtr at all in this scenario? It's impossible to know without you providing us the function prototype getting called. It's *probably* a ptr to a null-terminated char array. An API that returns data without providing a size in some way is not usable, so I'm sure it's there somewhere. Post more info and we can help! Tom > I am using Interop with a C++ function which returns a pointer to an > array of bytes. I'm using an IntPtr and Marshal.Copy to populate a [quoted text clipped - 3 lines] > way of accomplishing this? Should I be using IntPtr at all in this > scenario? Hello, This post has an interesting connection to a problem I am dealing with currently. I send an unmanaged array (unsigned chars) från unmanaged C++ to C# using P/Invoke and a callback/delegate. I use Marshal.Copy to copy the data to a managed array. For performance reasons I would perfer not to copy the data (large images) at all. However as I have control of the allocation of the unmanaged array and would like to create a managed "wrapper" array (which is considered to be pinned by the GC) which points to the unmanaged data. I have not been able to do this and and am therefore wondering if there are reasons for not doing this at all? As the binary layout of the managed array is just like a normal unmanaged array it would not seem impossible to do this. A solution which does not require me to copy the data is to allocated a managed array, pin the data (using a GCHandle) and pass it to the unmanaged code. Is this the only "no-copy" transfer of arrays from unmanaged to managed code possible? /Fredrik > It's impossible to know without you providing us the function prototype > getting called. [quoted text clipped - 15 lines] > > way of accomplishing this? Should I be using IntPtr at all in this > > scenario? Hej! Seem like I find the answer when I review older post. In the post "Is Marshal.Copy() really necessary to pass an array to/from managed/unmanaged code?" Mattias Sjögren answers a similar question. So it appear I could try using the unsafe keyword to access to data directly. /Fredrik > Hello, > [quoted text clipped - 20 lines] > > /Fredrik
Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
|
Reply to this Message
|
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.