DLL call sometimes works, sometimes crashes

[EDN Admin]

Hi, I have a question about a dynamically loaded library I am using. I have called it SqlWrite, it is for connecting and writing to a Microsoft SQL server DB. I have a function in it that is defined as:extern "C" {
__declspec(dllexport) RETCODE __cdecl SqlExecS(SQLHANDLESTR* h, std::string cmd)
{
RETCODE RetCode;

std::string input = cmd;
std::wostringstream conv;
conv << input.c_str();
std::wstring wCmd(conv.str());
WCHAR* wCCmd = const_cast<WCHAR*>(wCmd.c_str());


_setmode(_fileno(stdout), _O_WTEXT); // MSVCs special needs


std::wcout << "exec " << wCCmd;
RetCode = SQLExecDirect(h->hStmt,wCCmd, SQL_NTS);
std::wcout << " retcode " << RetCode << std::endl;
std::wcout << std::endl << "RETURNING FROM EXECSP NOW!!! " << std::endl;
return RetCode;
}
}
I then load it in another MSVC project as:
#ifdef WIN32// C:\Users\a\Documents\Visual Studio 2012\Projects\GetPageSource\Debug\GetPageSource.dll
#pragma message("WIN32 is defined")
#ifdef _DEBUG
SetErrorMode(0);
HINSTANCE hGetProcIDDLLGSP = LoadLibrary(L"C:\Users\a\Documents\Visual Studio 2012\Projects\GetPageSource\Debug\GetPageSource.dll");
HINSTANCE hGetProcIDDLLREGEX = LoadLibrary(L"C:\Users\a\Documents\Visual Studio 2012\Projects\regex\Debug\regex.dll");
HINSTANCE hGetProcIDDLLSQLWRITE = LoadLibrary(L"C:\Users\a\Documents\visual studio 2012\Projects\SQLWrite\Debug\SQLWrite.dll");
#else
#ifdef NDEBUG
SetErrorMode(0);
HINSTANCE hGetProcIDDLLGSP = LoadLibrary(L"C:\Users\a\Documents\Visual Studio 2012\Projects\GetPageSource\Release\GetPageSource.dll");
HINSTANCE hGetProcIDDLLREGEX = LoadLibrary(L"C:\Users\a\Documents\Visual Studio 2012\Projects\regex\Release\regex.dll");
HINSTANCE hGetProcIDDLLSQLWRITE = LoadLibrary(L"C:\Users\a\Documents\visual studio 2012\Projects\SQLWrite\Release\SQLWrite.dll");
#endif
#endif
#endif
#endif
. then I prototype it as:FARPROC lpfnGetProcessID = GetProcAddress(HMODULE (hGetProcIDDLLSQLWRITE),"SqlExecS");
std::cout << GetLastError() << std::endl;
/*
Define the Function in the DLL for reuse. This is just prototyping the dlls function.
*/
typedef RETCODE (__cdecl * pICFUNCSqlExecS)(SQLHANDLESTR* h, std::string cmd);

pICFUNCSqlExecS SqlExecSP;
SqlExecSP = pICFUNCSqlExecS(lpfnGetProcessID);


And, finally, I use it as, for example:SQLHANDLESTR * h = SqlConnectDBP();

if(h)
{

std::string comGP = std::string("SELECT [PlayerID], [FirstName], [LastName], [TeamID] FROM [soccer].[dbo].[Players] WHERE LastName = ");
comGP.append(plaDa->at(i).plName);
comGP.append(" AND FirstName = ");
comGP.append(plaDa->at(i).pfName);
comGP.append("");


SqlExecSP(h,comGP);
wcout << endl << " got player again " << endl;

}

As you can see, inside the prototyped function "SqlExecSP", I cout (or, rather, wcout for wide characters) the sql statement i am running, and the return code of the sql statement. a sql return code of "0" is equivalent to "SQL_SUCCESS". Then, I cout " got player again " after executon of SqlExecSP alias SqlExecS.
This usually works, and gives me following sample output:exec SELECT [PlayerID], [FirstName], [LastName], [TeamID] FROM [soccer].[dbo].[Players] WHERE LastName = Abdellaoue AND FirstName = Mohammed retcode 0

RETURNING FROM EXECSP NOW!!!

got player again
However, sometimes, the program, for some reason that I have no idea why, crashes somewhere between outputting "RETURNING FROM EXECSP NOW!!!" and outputting " got player again ", i.e. the output is then:exec SELECT [PlayerID], [FirstName], [LastName], [TeamID] FROM [soccer].[dbo].[Players] WHERE LastName = Abdellaoue AND FirstName = Mohammed retcode 0

RETURNING FROM EXECSP NOW!!!
As you can see, it doesnt output the next line " got player again ", because it somehow crashes in between.
However,t he only line that should be executed between this, as far as I can understand, is the actual return of the DLL function SqlExecS, prototyped as SqlExecSP in my calling code, i.e. the only line that should be executed in between is:return RetCode;
However, somehow, this fails, even though RetCode is "0", as I can see at the end of the outputexec SELECT [PlayerID], [FirstName], [LastName], [TeamID] FROM [soccer].[dbo].[Players] WHERE LastName = Abdellaoue AND FirstName = Mohammed retcode 0
Now, I have no idea why sometimes this crashes, and sometimes this works. I.e, I can sometimes call this function x times, and it doesnt fail, outputting " got player again " right after the calls, and sometimes, it fails somewhere in between, at call x, y, or z, i.e. sometimes i can execute it ten times successfully and sometimes i cant, even though the return code is still 0, and it just fails somewhere in between, and I have no idea why. I am not sure if it has to do with the call being a call to a dynamically loaded DLL function, but I cant see where else the error is.
Does anyone have ANY idea why this can be failing, and at different, seemingly random times?
Thanks for any input and help!!!
C

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