C# 如何在从C到C的结构中获取非托管变长C数组?
如何返回C# 如何在从C到C的结构中获取非托管变长C数组?,c#,pinvoke,marshalling,unmanaged,managed,C#,Pinvoke,Marshalling,Unmanaged,Managed,如何返回MIB\u IPFORWARDROW数组 struct MIB_IPFORWARDTABLE { public uint Size; [MarshalAs(/* what goes here? */)] public IPFORWARDROW[] Table; }; [DllImport("iphlpapi", CharSet = CharSet.Auto)] private static extern int GetIpForwardTable( I
MIB\u IPFORWARDROW
数组
struct MIB_IPFORWARDTABLE
{
public uint Size;
[MarshalAs(/* what goes here? */)]
public IPFORWARDROW[] Table;
};
[DllImport("iphlpapi", CharSet = CharSet.Auto)]
private static extern int GetIpForwardTable(
IntPtr /* MIB_IPFORWARDTABLE* */ pIpForwardTable,
ref uint /* ULONG* */ pdwSize,
bool bOrder);
public static MIB_IPFORWARDROW[] Temp()
{
var fwdTable = IntPtr.Zero;
uint size = 0;
var result = GetIpForwardTable(fwdTable, ref size, true);
fwdTable = Marshal.AllocHGlobal((int) size);
result = GetIpForwardTable(fwdTable, ref size, true);
/*
what now ?
I tried:
var table = (MIB_IPFORWARDTABLE) Marshal.PtrToStructure(fwdTable, typeof(MIB_IPFORWARDTABLE));
but table.Table is always null
*/
}
(见附件)
我看到了:
但无论我做什么,fwdTable.Table总是null,IntPtr.Zero或0。当然,如果没有引发异常..此线程似乎正是您要寻找的: 他们的解决方案使用蛮力循环将原始数组复制到IPFORWARDROW的System.array中 最终的代码如下所示:
[ComVisible(false), StructLayout(LayoutKind.Sequential)]
internal struct IPForwardTable
{
public uint Size;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 1)]
public IPFORWARDROW[] Table;
};
[ComVisible(false), StructLayout(LayoutKind.Sequential)]
internal struct IPFORWARDROW
{
internal int /*DWORD*/ dwForwardDest;
internal int /*DWORD*/ dwForwardMask;
internal int /*DWORD*/ dwForwardPolicy;
internal int /*DWORD*/ dwForwardNextHop;
internal int /*DWORD*/ dwForwardIfIndex;
internal int /*DWORD*/ dwForwardType;
internal int /*DWORD*/ dwForwardProto;
internal int /*DWORD*/ dwForwardAge;
internal int /*DWORD*/ dwForwardNextHopAS;
internal int /*DWORD*/ dwForwardMetric1;
internal int /*DWORD*/ dwForwardMetric2;
internal int /*DWORD*/ dwForwardMetric3;
internal int /*DWORD*/ dwForwardMetric4;
internal int /*DWORD*/ dwForwardMetric5;
};
[DllImport("iphlpapi", CharSet = CharSet.Auto)]
private extern static int GetIpForwardTable(IntPtr /*PMIB_IPFORWARDTABLE*/ pIpForwardTable, ref int /*PULONG*/ pdwSize, bool bOrder);
[DllImport("iphlpapi", CharSet = CharSet.Auto)]
private extern static int CreateIpForwardEntry(IntPtr /*PMIB_IPFORWARDROW*/ pRoute);
static void Main(string[] args)
{
var fwdTable = IntPtr.Zero;
int size = 0;
var result = GetIpForwardTable(fwdTable, ref size, true);
fwdTable = Marshal.AllocHGlobal(size);
result = GetIpForwardTable(fwdTable, ref size, true);
var str = (IPForwardTable)Marshal.PtrToStructure(fwdTable, typeof(IPForwardTable));
IPFORWARDROW[] table = new IPFORWARDROW[str.Size];
IntPtr p = fwdTable + Marshal.SizeOf(str.Size);
for (int i = 0; i < str.Size; ++i)
{
table[i] = (IPFORWARDROW)Marshal.PtrToStructure(p, typeof(IPFORWARDROW));
p += Marshal.SizeOf(typeof(IPFORWARDROW));
}
Marshal.FreeHGlobal(fwdTable);
}
[ComVisible(false),StructLayout(LayoutKind.Sequential)]
内部结构IPForwardTable
{
公共单位面积;
[Marshallas(UnmanagedType.ByValArray,SizeConst=1)]
公共IPROW[]表;
};
[ComVisible(false)、StructLayout(LayoutKind.Sequential)]
内部结构IPFORWARDROW
{
内部int/*DWORD*/dwForwardDest;
内部int/*DWORD*/dwForwardMask;
内部int/*DWORD*/dwForwardPolicy;
内部int/*DWORD*/dwForwardNextHop;
内部int/*DWORD*/dwforwardiIndex;
内部int/*DWORD*/dwForwardType;
内部int/*DWORD*/dwForwardProto;
内部int/*DWORD*/dwForwardAge;
内部int/*DWORD*/dwForwardNextHopAS;
内部int/*DWORD*/dwForwardMetric1;
内部int/*DWORD*/dwForwardMetric2;
内部int/*DWORD*/dwForwardMetric3;
内部int/*DWORD*/dwForwardMetric4;
内部int/*DWORD*/dwForwardMetric5;
};
[DllImport(“iphlapi”,CharSet=CharSet.Auto)]
私有外部静态int GetIpForwardTable(IntPtr/*PMIB_IPFORWARDTABLE*/pipfrowardtable,ref int/*PULONG*/pdwSize,bool bOrder);
[DllImport(“iphlapi”,CharSet=CharSet.Auto)]
私有外部静态int CreateIpForwardEntry(IntPtr/*PMIB_IPFORWARDROW*/pRoute);
静态void Main(字符串[]参数)
{
变量fwdTable=IntPtr.Zero;
int size=0;
var结果=GetIpForwardTable(fwdTable,ref size,true);
fwdTable=Marshal.AllocHGlobal(大小);
结果=GetIpForwardTable(fwdTable,ref size,true);
var str=(IPForwardTable)Marshal.PtrToStructure(fwdTable,typeof(IPForwardTable));
IPFORWARDROW[]表=新IPFORWARDROW[str.Size];
IntPtr p=fwdTable+Marshal.SizeOf(str.Size);
对于(int i=0;i
检查一下:@MichaelKniffen-我看不出它是如何关联的var str=(IPForwardTable)Marshal.PtrToStructure(fwdTable,typeof(IPForwardTable))代码>抛出NullReferenceException
oops。清理代码后,我删除了几个重要的代码(比如分配存储结果所需的内存)。编辑。