Is it a good idea to use intptr_t as a general-purpose storage (to hold pointers and integer values) instead of void*? No. intptr_t is not guaranteed to exist. First, as you note, it was introduced in C99. Second, implementations are not required to have an integer type big enough to hold converted pointer values without … Read more
As others have mentioned, there is no way you can store the data in a managed byte[] without copying (with the current structure you’ve provided*). However, if you don’t actually need it to be in a managed buffer, you can use unsafe operations to work directly with the unmanaged memory. It really depends what you … Read more
You can P/Invoke into the appropiate C function. That is probably the easiest way of doing that. Example: class Program { [DllImport(“kernel32.dll”, EntryPoint = “CopyMemory”, SetLastError = false)] public static extern void CopyMemory(IntPtr dest, IntPtr src, uint count); static void Main() { const int size = 200; IntPtr memorySource = Marshal.AllocHGlobal(size); IntPtr memoryTarget = Marshal.AllocHGlobal(size); … Read more
So if I want to pass a list to my callback function through WinApi I use GCHandle // object to IntPtr (before calling WinApi): List<string> list1 = new List<string>(); GCHandle handle1 = GCHandle.Alloc(list1); IntPtr parameter = (IntPtr) handle1; // call WinAPi and pass the parameter here // then free the handle when not needed: handle1.Free(); … Read more
If it’s a byte[] array: byte[] managedArray = new byte[size]; Marshal.Copy(pnt, managedArray, 0, size); If it’s not byte[], the size parameter in of Marshal.Copy is the number of elements in the array, not the byte size. So, if you had an int[] array rather than a byte[] array, you would have to divide by 4 … Read more
intptr_t is a new invention, created after 64-bit and even 128-bit memory addresses were imagined. If you ever need to cast a pointer into an integer type, always use intptr_t. Doing anything else will cause unnecessary problems for people who need to port your code in the future. It took a long time to iron … Read more
It’s a “native (platform-specific) size integer.” It’s internally represented as void* but exposed as an integer. You can use it whenever you need to store an unmanaged pointer and don’t want to use unsafe code. IntPtr.Zero is effectively NULL (a null pointer).