C#访问非托管内存

示例1：分配一个新的内存地址给新变量

Point p;
// Initialize unmanged memory to hold the struct.
IntPtr pnt = Marshal.AllocHGlobal(Marshal.SizeOf(p));
// Copy the struct to unmanaged memory.
Marshal.StructureToPtr(p, pnt, false);

// Create another point.
Point anotherP;

// Set this Point to the value of the 
// Point in unmanaged memory. 
anotherP = (Point)Marshal.PtrToStructure(pnt, typeof(Point));
Marshal.FreeHGlobal(pnt);

示例2：将一个字符串地址转换为字符串，以及获取字符串的地址：

IntPtr lpFileName;
string filename = Marshal.PtrToStringUni(lpFileName);
lpFileName = Marshal.StringToHGlobalUni(filename);

 示例3：字节数组到指针、指针到字节数组(来自微软官方的代码)

byte[] data = { 1, 2, 3, 4 };
            int size = Marshal.SizeOf(data[0]) * data.Length;
            var ptr = Marshal.AllocHGlobal(size);

            try
            {
                // Copy the array to unmanaged memory.
                Marshal.Copy(data, 0, ptr, data.Length);

                // Copy the unmanaged array back to another managed array.

                var data2 = new byte[data.Length];

                Marshal.Copy(ptr, data2, 0, data.Length);

                Console.WriteLine("The array was copied to unmanaged memory and back.");
            }
            finally
            {
                // Free the unmanaged memory.
                Marshal.FreeHGlobal(ptr);
            }