Re: Invalid pointer

=?Utf-8?B?dGhlamFja29mYWxs?= <>
Fri, 4 Jan 2008 14:18:03 -0800
I think I see something funny. Looking at my log file, I noticed
oInsertDependencies.push_back(pInsertDependency) is ok the first time. On
the second execution of the line, it says Invalid pointer. Please take a
look at the code below.

fDebug << "Insert Dependency" << endl;

for (long nn = 0; pNodeList1->length; nn++)
     pNode1 = NULL;
     pNodeList1->get_item(nn, &pNode1);
     pNamedNodeMap = pNode1->Getattributes();
     pNode2 = pNamedNodeMap->getNamedItem(L"Id");
     _bstr_t ID = pNode2->Gettext();

     _bstr_t MustBeforeLink = "false";
     pNode2 = pNamedNodeMap->getNamedItem(L"MustBeforeLink");

     if (pNode2 != NULL)
          MustBeforeLink = pNode2->Gettext();

     fDebug << "ID: " << ID << " MustBeforeLink: " << MustBeforeLink << endl;

     InsertDependency* pInsertDependency = new InsertDependency((LPCTSTR)
ID, (LPCTSTR) MustBeforeLink);

     if (pInsertDependency == NULL)
          fDebug << "NULL" << endl;
          fDebug << "NOT NULL" << endl;

     // when nn == 0, it's ok
     // when nn == 1, it's invalid pointer

Appreciate your help.
Be Cool!

"Victor Bazarov" wrote:

thejackofall wrote:

thejackofall wrote:

I am doing the following:

InsertDependencies oInsertDependencies =

Are you copying the list here? Does 'pLink' survive untile the
point where you're using 'oInsertDependencies'? Are the contents
of 'oInsertDependencies' OK?

I am not copying the list, but get the reference to the list which

Yes, you *are* copying it. To get the reference you'd write

    InsertDependencies & oInsertDependencies = ...

would contain the InsertDependency*. I specified typedef
std::list<InsertDependency*> InsertDependencies. pLink does survive
to the end.

That would mean that the pointers that exist in the list and are
copied here do not interfere, most likely, with the rest of the

// ID and MustBeforeLink is _bstr_t with correct data
InsertDependency* pInsertDependency = new InsertDependency((LPCTSTR)
ID, (LPCTSTR) MustBeforeLink);

When this allocation happens, does 'pInsertDependency' look OK?
Have you tried putting a breakpoint on the next statement and look
at 'pInsertDependency' value?

pInsertDependency looks ok. I put the following code and it's fine.

if (pInsertDependency == NULL)
 fDebug << "NULL << endl;
 fDebug << "NOT NULL" << endl;

It writes NOT NULL as a result.

The pointer doesn't have to be NULL to be invalid. Try dereferencing
the pointer.

fDebug << "Test" << endl;

oInsertDependencies.push_back(pInsertDependency); // Invalid pointer

Have you tried running under a debugger? Which pointer is invalid?

Unfortunately, I can't run under a debugger because it's a server

Yes, you should be able to. It's not impossible. People debug server
components every day. You just need to learn how to do it.

I recall putting a MessageBox in my server component to hold its
execution and then attaching the debugger to the running process to
see what's going on there. Once the debugger has attached itself
to the process, let the process continue by pressing 'OK' on the
message box, and it will stop at the breakpoints, and show you the
values, and the code and all that.

The pointer is valid, but the list isn't accepting it.

How can the list not accept it? The list doesn't care what value
you put there. It only copies it into its storage. Even an invalid
pointer value is copiable. 'std::list' will not verify what pointer
you give it.

On the last line, it generates the "Invalid pointer" error. The
word "Test" writes out fine. InsertDependencies had the following

typedef std::list<InsertDependency*> InsertDependencies;

Appreciate your help.

Can't really help you much, you didn't post nearly enough code to
suggest anything meaningful.

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Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

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