I have a function in unmanaged C/C++ code (dll) that returns a structure containing a char array. I created C# struct to receive this return value uppon calling the function. And uppon calling this function i get 'System.Runtime.InteropServices.MarshalDirectiveException'
This is C declaration:
typedef struct T_SAMPLE_STRUCT {
int num;
char text[20];
} SAMPLE_STRUCT;
SAMPLE_STRUCT sampleFunction( SAMPLE_STRUCT ss );
This is C# declaration:
struct SAMPLE_STRUCT
{
public int num;
public string text;
}
class Dllwrapper
{
[DllImport("samplecdll.dll")]
public static extern SAMPLE_STRUCT sampleFunction(SAMPLE_STRUCT ss);
}
I am using 1-byte ASCII.
Does anyone has a hint or a solution on how to do this?
The trick to converting a C array member is to use the MarshalAs(UnmanagedType.ByValTStr). This can be used to tell the CLR to marshal the array as an inlined member vs. a normal non-inlined array. Try the following signature.
[System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential, CharSet=System.Runtime.InteropServices.CharSet.Ansi)]
public struct T_SAMPLE_STRUCT {
/// int
public int num;
/// char[20]
[System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=20)]
public string text;
}
public partial class NativeMethods {
/// Return Type: SAMPLE_STRUCT->T_SAMPLE_STRUCT
///ss: SAMPLE_STRUCT->T_SAMPLE_STRUCT
[System.Runtime.InteropServices.DllImportAttribute("<Unknown>", EntryPoint="sampleFunction")]
public static extern T_SAMPLE_STRUCT sampleFunction(T_SAMPLE_STRUCT ss) ;
}
This signature is brought to you by the PInovke Interop Assistant (link) available on CodePlex. It can automatically translate most PInvoke signatures from native code to C# or VB.Net.
This is not an easy structure for P/Invoke to marshal: it's easier to marshal structures that contain char* instead of char[] (although you're then left with the problem of allocating the char* from unmanaged code and later freeing it from managed code).
Assuming you're sticking with the current design, one option is to declare the string array as:
public fixed char text[20];
Unfortunately you must then add the unsafe keyword to any code that accesses this array.
Struct definition in C:
#pragma pack(push, 1)
typedef struct T_SAMPLE_STRUCT {
int num;
char text[20];
};
#pragma pack(pop)
Definition in C#:
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)]
public struct T_SAMPLE_STRUCT
{
[MarshalAs(UnmanagedType.I4)]
public int num;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 20)]
public string text;
}
I have managed to do this by separating function to:
void receiveStruct( SAMPLE_STRUCT ss )
void returnStruct(SAMPLE_STRUCT &ss)
I have changed struct definition as JaredPar told me:
[StructLayoutAttribute(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct T_SAMPLE_STRUCT
{
/// int
public int num;
/// char[20]
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 20)]
public string text;
}
And now it works.
Thanks!
As an interesting aside, since you already have the answer, the basic issue here is that the struct just needs to be the right size. Since managed types don't have inline arrays, you just have to make up the space that it would otherwise need. When you write in C++/CLI, you'll often see the StructLayoutAttribute with an explicit Size parameter. This makes the runtime allocate the right amount of memory for the type, which allows it to be blittable to the native side. It follows that these should work, as well:
[StructLayout(LayoutKind.Sequential, Size=24)]
public struct T_SAMPLE_STRUCT
{
public int num;
// to get the string here, you'd need to get a pointer
public char firstChar;
}
// or
[StructLayout(LayoutKind.Sequential)]
public struct T_SAMPLE_STRUCT
{
public int num;
public byte c0;
public byte c1;
public byte c2;
public byte c3;
public byte c4;
public byte c5;
public byte c6;
public byte c7;
public byte c8;
public byte c9;
public byte c10;
public byte c11;
public byte c12;
public byte c13;
public byte c14;
public byte c15;
public byte c16;
public byte c17;
public byte c18;
public byte c19;
}
Of course, these are much harder to use from managed code (you'd need to copy memory or use pointers), but they illustrate the concept of a blittable type, which is primarily how types are passed between native and managed code.
First you have to put
StructLayout[Sequential] attribute on your struct and I think it will work
[ StructLayout( LayoutKind.Sequential, CharSet=CharSet.Ansi )]
struct SAMPLE_STRUCT
{
public int num;
[ MarshalAs( UnmanagedType.ByValArray, SizeConst=20 )]
public char[] text;
}
Related
I'm write a plugin with c# . the program with c# will use a dll which writes by c ,so I have to call c function in my c# program ,but unfortunately the c function's parameter is a struct and it is so complex that I never find any
help information about how to convert it to c# parameter.
the struct has an embedded function and void* parameter ,I didn't find anyway to convert them to c#.
the struct is mostly like this
struct first_struct{
char* parameter1;
int parameter2;
unsigned long parameter3;
unsigned short parameter4;
void* parameter5;
int (*parameter6)(int,void *);
second_struct parameter7;
};
struct second_struct{
char parameter8[64] ;
char parameter9[256];
};
I want change this c struct to c# struct but I have no idea how to do it
thanks #Biesi Grr and #Ian Abbott ‘s help it sames that I can change the c struct to c# like that.
public delegate int parameter6(int volcnt, System.IntPtr vod);
[StructLayout(LayoutKind.Sequential)]
public struct csharp_firstSturct
{
[MarshalAs(UnmanagedType.LPStr)]
public string parameter1;
public int parameter2;
public ulong parameter3;
public ushort parameter4;
public System.IntPtr parameter5;
public parameter6 m_parameter6;
}
but I still has no idea about how to convert parameter7 from C to C#,what should I do to convert parameter7 form c to c#.
Assuming your char arrays are null terminated strings you can do it the following way
public delegate int parameter6(int volcnt, System.IntPtr vod);
[StructLayout(LayoutKind.Sequential)]
public struct csharp_firstSturct
{
[MarshalAs(UnmanagedType.LPStr)]
public string parameter1;
public int parameter2;
public ulong parameter3;
public ushort parameter4;
public System.IntPtr parameter5;
public parameter6 m_parameter6;
[MarshalAs(UnmanagedType.Struct)]
public second_struct parameter7;
}
[StructLayout(LayoutKind.Sequential)]
public struct second_struct
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 64)]
public string parameter8;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
public string parameter9;
}
Hi i got problems to handle information between an unmanaged dll and my C# code.
The function in my C dll is:
int import_large_string(struct sha_struct *sha_s,
const char *large_string);
That import the large_string and transform into sha_s, the struct sha_struct is the following:
struct sha_struct
{
struct information *info;
struct info_cfg cfg;
};
And the information struct is something like
struct information
{
int version;
char serial_number[16];
uint16_t exp_date;
};
In C# i imported the function import_large_string like this:
[DllImport("functionalDLL.dll", EntryPoint = "import_large_string", CharSet = CharSet.Ansi)]
public static int import_large_string(ref sha_struct sha_s, string large_string);
When i called the function, it suppose to store information in sha_struct sha_s, but i only have a random 8 digit number in sha_s.information.version not in the whole struct, what am I doing wrong?
Edited
My structs in C# are:
[StructLayout(LayoutKind.Sequential)]
public struct sha_struct
{
public information t;
public info_cfg cfg;
};
[StructLayout(LayoutKind.Sequential)]
public struct information
{
public int version;
public string serial_number;
public ushort exp_date;
};
[StructLayout(LayoutKind.Sequential)]
public struct info_cfg
{
public string release_version;
public string release_string;
public string release_password;
};
As pointed out by #DavidHeffernan, you want to use the MarshalAs attribute on your string field:
[StructLayout(LayoutKind.Sequential)]
public struct information
{
public int version;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst=16)]
public string serial_number;
public ushort exp_date;
};
As illustrated on this documentation link.
I am trying to call a function from C# to a .DLL written in Borland C++ whose signature is:
extern "C" __declspec(dllexport) ls50errortype __stdcall Ls50P2Open(ls50p2apiconfiginfostruct &configinfo);
The corresponding call in C#:
[DllImport("C:\\Lumistar\\LDPS_8x\\Ls50P2_Dll.dll", EntryPoint = "Ls50P2Open", CallingConvention = System.Runtime.InteropServices.CallingConvention.StdCall, CharSet = CharSet.Ansi, SetLastError = true)]
public static extern void Ls50P2Open(ref ls50p2apiconfiginfostruct configinfo);
The structure of interest (ls50p2apiconfiginfostruct) is composed of nested structures and enums (copied from the C++ header):
typedef enum
{
MFMODEL_LS50P1,
MFMODEL_4422PCI,
MFMODEL_LS50P2,
MFMODEL_LS70P2,
MFMODEL_LS5070,
MFMODEL_LAST
}ecardmodel;
typedef enum
{
CHANNELDEVICE_NONE,
CHANNELDEVICE_50,
CHANNELDEVICE_70,
CHANNELDEVICE_LAST
}ls50p2channeldevicetype;
typedef enum
{
LS50V2DCARD_NONE,
LS50V2DCARD_40V1_10,
LS50V2DCARD_40V1_20,
LS50V2DCARD_40V2_10,
LS50V2DCARD_40V2_20,
LS50V2DCARD_38,
LS50V2DCARD_LAST
}ls50p2daughtercardtype;
typedef struct
{
bool HasDaughterCard;
ls50p2daughtercardtype DCardType;
bool SpecialStatusCapable;
int MaxBitsyncInputs;
bool HasBitsyncConfidenceLevel;
bool HasBitsync2ndCh;
bool SpecialStatusCapable2ndCh;
bool HasBitsyncConfidenceLevel2ndCh;
ls50p2daughtercardtype DCardType2ndCh;
int MaxBitsyncInputs2ndCh;
}ls50p2daughtercardinfostruct;
typedef struct
{
ecardmodel DeviceModel;
ls50p2channeldevicetype ChannelDataTypeAry[2];
ls50p2daughtercardinfostruct DaughterCardInfo;
bool HasExtendedBertPatterns;
int FirmwareVersionAry[2];
int NumPremodFiltersAry[2];
double Ls50SimPreModFilterKhzAry[2][LS50V2_MAX50SIMPREMODFILTERS];
double Ls50SimMinFmDeviationKhzAry[2];
double Ls50SimMaxFmDeviationKhzAry[2];
}ls50p2cardconfigstruct;
typedef struct
{
unsigned char *DataBuf;
HANDLE hNewDataRdy;
DWORD MaxBufLength;
DWORD CurrentBufLength;
int NumHeaderBytes;
}ls50p2carddatastruct;
typedef struct
{
ls50p2cardconfigstruct CardConfigInfo[MAXMFCARDS];
int Ls50P2CardCount;
ls50p2carddatastruct DataInfo[MAXMFCARDS][2];
}ls50p2apiconfiginfostruct;
Here's the corresponding struct in C#:
public enum ecardmodel
{
MFMODEL_LS50P1,
MFMODEL_4422PCI,
MFMODEL_LS50P2,
MFMODEL_LS70P2,
MFMODEL_LS5070,
MFMODEL_LAST
}
public enum ls50p2channeldevicetype
{
CHANNELDEVICE_NONE,
CHANNELDEVICE_50,
CHANNELDEVICE_70,
CHANNELDEVICE_LAST
};
public enum ls50p2daughtercardtype
{
LS50V2DCARD_NONE,
LS50V2DCARD_40V1_10,
LS50V2DCARD_40V1_20,
LS50V2DCARD_40V2_10,
LS50V2DCARD_40V2_20,
LS50V2DCARD_38,
LS50V2DCARD_LAST
}
[StructLayout(LayoutKind.Sequential)]
public struct ls50p2daughtercardinfostruct
{
public bool HasDaughterCard;
public ls50p2daughtercardtype DCardType;
public bool SpecialStatusCapable;
public int MaxBitsyncInputs;
public bool HasBitsyncConfidenceLevel;
public bool HasBitsync2ndCh;
public bool SpecialStatusCapable2ndCh;
public bool HasBitsyncConfidenceLevel2ndCh;
public ls50p2daughtercardtype DCardType2ndCh;
public int MaxBitsyncInputs2ndCh;
}
[StructLayout(LayoutKind.Sequential)]
public struct ls50p2cardconfigstruct
{
public ecardmodel DeviceModel;
public ls50p2daughtercardtype[] ChannelDataTypeAry;
public ls50p2daughtercardinfostruct DaughterCardInfo;
public bool HasExtendedBertPatterns;
public int[] FirmwareVersionAry;
public int[] NumPremodFiltersAry;
public double[] Ls50SimPreModFilterKhzAry;
public double[] Ls50SimMinFmDeviationKhzAry;
public double[] Ls50SimMaxFmDeviationKhzAry;
}
[StructLayout(LayoutKind.Sequential)]
public struct ls50p2carddatastruct
{
public StringBuilder DataBuf;
public IntPtr hNewDataRdy;
public uint MaxBufLength;
public uint CurrentBufLength;
public int NumHeaderBytes;
}
[StructLayout(LayoutKind.Sequential)]
public struct ls50p2apiconfiginfostruct
{
public ls50p2cardconfigstruct[] CardConfigInfo;
public int Ls50P2CardCount;
public ls50p2carddatastruct[,] DataInfo;
}
Here's the code in C# that I use to call the function:
ls50p2apiconfiginfostruct lscfg = new ls50p2apiconfiginfostruct();
lscfg.CardConfigInfo = new ls50p2cardconfigstruct[8];
for (int i = 0; i < 8; i++)
{
lscfg.CardConfigInfo[i].ChannelDataTypeAry = new ls50p2daughtercardtype[2];
}
lscfg.DataInfo = new ls50p2carddatastruct[8, 2];
Ls50P2Open(ref lscfg);
I have tried making this struct in C# but I haven't had much success (problems with enums, 2D arrays, fixed sized buffers). What is the correct way to create this structure in C#? Would this need to be done in an unsafe context?
Now for some reason I get the following error when running the code:
An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in Library.dll
Additional information: Old format or invalid type library. (Exception from HRESULT: 0x80028019 (TYPE_E_UNSUPFORMAT))
What does your C# structure looks like. Are you using the StructLayoutAttribute?
http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.structlayoutattribute.aspx
You can use it with the option sequential so you just would have to fill your c# structure with fields in the right order.
I believe the array problem is more or less answered here; Improper marshaling: C# array to a C++ unmanaged array
The accepted answer shows how to safely marshal a dynamically allocated array.
As for the enums, they shouldn't pose any problems, there is a clean 1:1 mapping. In fact, I would do it as described in this msdn post; http://blogs.msdn.com/b/abhinaba/archive/2007/08/27/sharing-enums-across-c-and-c.aspx
You can simply define all your enums in a .cs file then include it in both projects and everything will work fine.
I try to Marshal a unmanaged c++ dll in c#, but the marshaller fails when creating my union.
Why does this code fail?
[StructLayout(LayoutKind.Sequential)]
public struct StructWithArray
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
public int[] MySimpleArray;
//More Stuff
}
[StructLayout(LayoutKind.Explicit)]
public struct Union
{
[FieldOffset(0)]
public int Int; //Or anything else
[FieldOffset(0), MarshalAs(UnmanagedType.Struct)]
public StructWithArray MyStructWithArray;
//More Structs
}
And then constructing the Union:
Union MyUnion = new Union();
It fails if I run the code with the following Message: (Translated)
{"The Type "Union" of the Assembly [...] could not be loaded because it contained an Objectfield at Offset 0, which is not aligned correctly or got overlapped by a field which isnt a ObjectField":"Union"}
Any Suggestions?
Ps: The original code is heavily simplified to show only the Problem. There are much more Structs, and the Union is also contained by another Struct.
Declare MySimpleArray as a fixed unsafe array:
[StructLayout(LayoutKind.Sequential)]
public unsafe struct StructWithArray
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
public fixed int MySimpleArray[2];
//More Stuff
}
[StructLayout(LayoutKind.Explicit)]
public struct Union
{
[FieldOffset(0)]
public int Int; //Or anything else
[FieldOffset(0), MarshalAs(UnmanagedType.Struct)]
public StructWithArray MyStructWithArray;
//More Structs
}
I have the following struct in C++:
#define MAXCHARS 15
typedef struct
{
char data[MAXCHARS];
int prob[MAXCHARS];
} LPRData;
And a function that I'm p/invoking into to get an array of 3 of these structures:
void GetData(LPRData *data);
In C++ I would just do something like this:
LPRData *Results;
Results = (LPRData *)malloc(MAXRESULTS*sizeof(LPRData));
GetData( Results );
And it would work just fine, but in C# I can't seem to get it to work.
I've created a C# struct like this:
public struct LPRData
{
/// char[15]
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 15)]
public string data;
/// int[15]
[MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 15)]
public int[] prob;
}
And if I initialize an array of 3 of those (and all their sub-arrays) and pass it into this:
GetData(LPRData[] data);
It returns with success, but the data in the LPRData array has not changed.
I've even tried to create a raw byte array the size of 3 LPRData's and pass that into a function prototype like this:
GetData(byte[] data);
But in that case I will get the "data" string from the very first LPRData structure, but nothing after it, including the "prob" array from the same LPRData.
Any ideas of how to properly handle this?
I would try adding some attributes to your struct decloration
[StructLayout(LayoutKind.Sequential, Size=TotalBytesInStruct),Serializable]
public struct LPRData
{
/// char[15]
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 15)]
public string data;
/// int[15]
[MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 15)]
public int[] prob;
}
*Note TotalBytesInStruct is not intended to represent a variable
JaredPar is also correct that using the IntPtr class could be helpful, but it has been quite awhile since I have used PInvoke so I'm rusty.
One trick when dealing with pointers is to just use an IntPtr. You can then use Marshal.PtrToStructure on the pointer and increment based on the size of the structure to get your results.
static extern void GetData([Out] out IntPtr ptr);
LPRData[] GetData()
{
IntPtr value;
LPRData[] array = new LPRData[3];
GetData(out value);
for (int i = 0; i < array.Length; i++)
{
array[i] = Marshal.PtrToStructure(value, typeof(LPRData));
value += Marshal.SizeOf(typeof(LPRData));
}
return array;
}
A similar topic was discussed on this question, and the one of the conclusions was that the CharSet named parameter must be set to CharSet.Ansi. Otherwise, we would be making a wchar_t array instead of a char array. Thus, the correct code would be as follows:
[Serializable]
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct LPRData
{
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 15)]
public string data;
[MarshalAsAttribute(UnmanagedType.ByValArray, SizeConst = 15)]
public int[] prob;
}
The PInvoke Interop Assistant may help. http://clrinterop.codeplex.com/releases/view/14120
Did you mark GetData parameter with OutAttribute?
Combining the InAttribute and
OutAttribute is particularly useful
when applied to arrays and formatted,
non-blittable types. Callers see the
changes a callee makes to these types
only when you apply both attributes.