[英]Marshal.Copy, copying an array of IntPtr into an IntPtr
I can't figure out how does the Copy(IntPtr[], Int32, IntPtr, Int32)
method works. 我无法弄清楚
Copy(IntPtr[], Int32, IntPtr, Int32)
方法是如何工作的。 I though it could copy the data contained in multiple IntPtrs into a single IntPtr (as MSDN states) but apparently it doesn't work as I expected: 我虽然它可以将多个IntPtrs中包含的数据复制到一个IntPtr(作为MSDN状态),但显然它不能像我预期的那样工作:
IntPtr[] ptrArray = new IntPtr[]
{
Marshal.AllocHGlobal(1),
Marshal.AllocHGlobal(2)
};
Marshal.WriteByte(ptrArray[0], 0, 0xC1);
// Allocate the total size.
IntPtr ptr = Marshal.AllocHGlobal(3);
Marshal.Copy(ptrArray, 0, ptr, ptrArray.Length);
// I expect to read 0xC1 but Value is always random!!
byte value = Marshal.ReadByte(ptr, 0);
Does someone know if I'm using this method for something that it is not its purpose? 有人知道我是否正在使用这种方法而不是它的目的吗?
static void Main(string[] args)
{
IntPtr[] ptrArray = new IntPtr[]
{
Marshal.AllocHGlobal(1),
Marshal.AllocHGlobal(2)
};
Marshal.WriteByte(ptrArray[0], 0, 100);
int size = Marshal.SizeOf(typeof(IntPtr)) * ptrArray.Length;
IntPtr ptr = Marshal.AllocHGlobal(size);
Marshal.Copy(ptrArray, 0, ptr, ptrArray.Length);
// Now we have native pointer ptr, which points to two pointers,
// each of thme points to its own memory (size 1 and 2).
// Let's read first IntPtr from ptr:
IntPtr p = Marshal.ReadIntPtr(ptr);
// Now let's read byte from p:
byte b = Marshal.ReadByte(p);
Console.WriteLine((int)b); // prints 100
// To do: release all IntPtr
}
Read explanations in the comments. 阅读评论中的解释。
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