C++ :: Dynamically Loaded Library - DLL Call Sometimes Works

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, LPCSTR Statement) {
RETCODE RetCode;

std::string input = Statement;
std::wostringstream conv;
conv << input.c_str();
std::wstring wCmd(conv.str());

[Code] ....

I then load it in another MSVC project as:

#ifdef WIN32//C:UsersaDocumentsVisual Studio 2012ProjectsGetPageSourceDebugGetPageSource.dll
#pragma message("WIN32 is defined")
#ifdef _DEBUG
SetErrorMode(0);

[Code] ....

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 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 doesn't 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 output

exec SELECT [PlayerID], [FirstName], [LastName], [TeamID] FROM [soccer].[dbo].[Players] WHERE LastName = 'Abdellaoue' AND FirstName = 'Mohammed' retcode 0

Now, 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 can't, even though the return code is still 0, and it just fails somewhere in between. I am not sure if it has to do with the call being a call to a dynamically loaded DLL function, but I can't see where else the error is.

Why this can be failing, and at different, seemingly random times?