Access violation in my DLL after createparameter()

Question

1.00/5 (1 vote)

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C++

CommandPtr pCmd = NULL;
_ParameterPtr Var1;
Var1 = pCmd->CreateParameter(_bstr_t("@T"), adInteger, adParamOutput, 0, codRet);

Why do I get Access violation writing... error in my dll on this string? How do I fix it?
Thx. I'm using VS 2015.

This is the full code:

C++

 CommandPtr pCmd = NULL;
_ConnectionPtr pConnection = NULL;
_bstr_t strMessage, strAuthorID;

::CoInitialize(NULL);

long codRet = -1;

try {

    _ParameterPtr Var1;


    TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
    hr = pConnection->Open("Driver={SQL Server};Server=conn_string", "", "", adConnectUnspecified);

    pConnection->CursorLocation = adUseClient;
    TESTHR(pCmd.CreateInstance(__uuidof(Command)));
    pCmd->CommandText = PrcName;
    pCmd->CommandType = adCmdStoredProc;

    Var1 = pCmd->CreateParameter(_bstr_t("@T"), adInteger, adParamOutput, 0, codRet);

What I have tried:

Trying to use my dll in 3d party application. DLL compiled successfully.

Posted 27-Jun-17 9:19am

Member 13277231

Updated 27-Jun-17 10:22am

v2

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Comments

Richard Deeming 27-Jun-17 15:34pm

Just because it compiles, that doesn't necessarily mean it's correct! :)

Member 13277231 27-Jun-17 15:40pm

of course... So what might be a error?

Richard Deeming 27-Jun-17 15:45pm

There are all sorts of possibilities. But without seeing the relevant parts of your code, there's very little chance that anyone will be able to tell you what the problem is.

Click the green "Improve question" link, and add the relevant parts of your DLL code to the question.

Then you'll just need to wait for someone who "does" C++ (I don't) to see if they can spot the problem.

Member 13277231 27-Jun-17 16:08pm

I did. Thank you.

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Member 13277231 · Answer 1 · 2017-06-27T10:22:00

Solution 1

CreateParameter(_bstr_t("@T"), adInteger, adParamOutput, 0, codRet);

The error seems to be was in 4th parameter which is size. I put 1 instead 0 and no error :)

CreateParameter Method (ADO) | Microsoft Docs[^]

Posted 27-Jun-17 10:22am

Member 13277231