StructLayout 和 FieldOffset 的未定义行为

Question

我已经使用 PtrToStructure 函数(在 VB.NET 中(成功地从有效指针中提取了一个结构对象，但某些对象成员的结果不正确(与C++示例相比(：

代码是：

StructLayout(LayoutKind.Explicit, pack:=1, CharSet:=CharSet.Ansi)> _
Public Structure MyStruct
<FieldOffset(0)> _
Dim Width As UInt32 ' 350 correct
<FieldOffset(4)> _
Dim Height As UInt32 ' 466 correct
<FieldOffset(20)> _
Dim Buffer As IntPtr ' variable but correct
<FieldOffset(24)> _
Dim BufferPitch As Integer ' 1408 correct
<FieldOffset(16)> _
Dim SurfaceType As Integer ' -2147483645 correct
<FieldOffset(unknow)> _
Dim WindowWidth As UInt32 ' must be 356, tested from 0 to 230
<FieldOffset(unknow)> _
Dim WindowHeight As UInt32 ' must be 495, tested from 0 to 100
<FieldOffset(15)> _
Dim ScreenHeight As UInt32 ' 768 correct
<FieldOffset(36)> _
Dim ScreenWidth As UInt32 ' 1366 correct
<FieldOffset(44)> _
Dim ScreenDepth As UInt32 ' 32 correct
End Structure

我找不到 WindowWidth 和 WindowHeight 的 FieldOffset 参数的确切值。 问题是为什么以及如何修复它们？

struct myStruct 
{ 
U32 Width; // U32 = 32-bit unsigned integer 
U32 Height; 
VOID_PTR Buffer;
S32 BufferPitch; // 32-bit signed integer 
COPY_FLAGS SurfaceType; // integer 
U32 WindowWidth; 
U32 WindowHeight; 
U32 ScreenWidth; 
U32 ScreenHeight; 
U32 ScreenDepth; 
}

Answer 1

这个问题就解决了。 通过更改位于 8 和 12 中的偏移量并按另一个值修改指针参数。