C# to unmanaged C++

**MottetCCSF** · Jul 17 '09, 06:38 AM

I have created 2 structures in my C# code :

Code:

        [StructLayoutAttribute(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        public class RollInformationCSharp
        {
            [MarshalAs(UnmanagedType.R8)]
            public double rollDiameter;

            [MarshalAs(UnmanagedType.R8)]
            public double initialRoughness;

            [MarshalAs(UnmanagedType.R8)]
            public double finalRoughness;

            [MarshalAs(UnmanagedType.R8)]
            public double accumulateCombination;

            [MarshalAs(UnmanagedType.R8)]
            public double critialRollLength;

            [MarshalAs(UnmanagedType.R8)]
            public double rolledLength;

            [MarshalAs(UnmanagedType.R8)]
            public double percentageLifeRoll;

            [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 256)]
            public string rollName;
         };

and :

Code:

      [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        public class MultiRollCSharp
        {
            [MarshalAs(UnmanagedType.I4)]
            public int nbRoll;

            public RollInformationCSharp[] tabRoll;
        }

In the C# code, i invoke a function of C++ dll :

Code:

        [DllImport("DLL_RaFTmodel.dll", CharSet = CharSet.Ansi)]
        public static extern IntPtr DLL_FlesCalculation(MultiRollCSharp multiRollInfo,
                                              CoilInformationCSharp coilInfo,
                                              RollInformationCSharp rollInfo,
                                              LimitsTypeCSharp LimitsSteel,
                                              LimitsTypeCSharp LimitsRegulation,
                                              LimitsTypeCSharp LimitsMachine,
                                              FTInputsCsharp forceTensionInfo,
                                              RaConstantsCSharp RaModelIn,
                                              FTWeightCsharp FTmodelIn,
                                              [In, MarshalAs(UnmanagedType.I4)] int strategy,
                                              [In, MarshalAs(UnmanagedType.I4)] int rollLifeMaximization,
                                              RaInputsCsharp RaDataIn,
                                              char Version,
                                              [In, MarshalAs(UnmanagedType.R4)] float errMax,
                                              [Out, MarshalAs(UnmanagedType.I4)] out int error);

In C++, I have also 2 structures :

Code:

struct RollInformation
{
	double rollDiameter;
	double initialRoughnessRoll;
	double finalRoughnessRoll;
	double accumulateCombination;
	double percentageLifeRoll;
	double criticalRollLength;
	double rolledLength;
	char rollName[256];
};

and

Code:

struct MultiRollInformation
{
	int nbRoll;
	RollInformation* tabRoll;
};

The function is also declared as follow :

Code:

extern EXPORTTOTEM_API 
MULTICURVETYPE* DLL_FlesCalculation( struct MultiRollInformation *multiRollInfo,									 struct CoilInformation *coilInfo, 
			 struct RollInformation *rollInfo,
			 struct LimitsType *LimitsSteel,
			 struct LimitsType *LimitsRegulation,
			 struct LimitsType *LimitsMachine,
			 struct FTInputs *forceTensionInfo,
			 struct RaConstants *constRaIn,
			 struct FTWeight *modelFTIn,
			 int strategy,
			 int rollLifeMaximization,
			 struct RaInputs *dataRaIn,
		                 char Version,
			 float errMax,
			 int &error);

Example to fill the structure in C# :

Code:

            MultiRollCSharp multiRollInfo = new MultiRollCSharp();
            for(int i = 0; i < 5; i++)
            {
                RollInformationCSharp rollInfo1 = GetRollInformation();
                int taille = 0;
                if (multiRollInfo.tabRoll != null)
                    taille = multiRollInfo.tabRoll.Length;

                RollInformationCSharp[] tab = new RollInformationCSharp[taille +1];
                if (taille > 0)
                {
                    multiRollInfo.tabRoll.CopyTo(tab, 0);
                }
                tab[tab.Length-1] = rollInfo1;
                multiRollInfo.tabRoll = tab;

                multiRollInfo.nbRoll += 1;
            }

In debug mode, just before the call to the DLL, the both structures in C# are right (multiRollInfo and rollInfo)
.
In C++, the rollInfo is good. But the the multiroll info has 5 elements but there values are wrong .

What is wrong?
How can I correct this?

thank you very much for your help