Re: An STL string leak

dushkin <>
Tue, 6 Jul 2010 00:04:37 -0700 (PDT)
Thanks Joe, please see below comments...

On Jul 5, 8:49 pm, Joseph M. Newcomer <> wrote:

See below...

On Mon, 5 Jul 2010 08:13:29 -0700 (PDT), dushkin <> wrot=


More important information...

The original string is created as:

                           COleDateTime now=

 = COleDateTime::GetCurrentTime();

                           CString sFormat;


                           CString sNow ==


and I cast it to string as (LPCTSTR)sNow.

When do you cast it, and why?

I cast the CString sNow to a string object. This is in order to pass
it to an object member which requires a string object in its
But I also tried to initiate this string member with the current time
inside the constructor - without passing it to the ctor and without
casting, and the same leak occurred.

Note that this will not affect the "leak" issue. The leak issue is bec=

ause the object is

not being deleted.

Are you sure the delete operator is actually being called?

I am sure the I call the delete of this object, but I am afraid that I
miss something..
The pointer address that we see in the leak message is of an inner
pointer of the string object which is a member of the object which I
As I tried to explain in my first post, the object that I delete is of
type CB and it has the string member.
When it is deleted, the string leaks. And in more detail: there is
some _Bx->_Ptr of this string which leaks (according to the address in
the leak message)

By the way, I also tried

time_t tm;
string sNow = FormatTime(tm);

string FormatTime( const time_t time )
    struct tm ts;
    char szBuffer[80] = "DD-MM-YY HH:MM:SS";

    errno_t err = localtime_s(&ts,&time);

    if (err)
        // Format the time
        strftime(szBuffer, sizeof(szBuffer), "%d-%b-%Y %X%p", &ts);
    return szBuffer;

which spared me from using casting and the same result occurred. This
is the code that I use now inside CB ctor to initialize the string

If I wanted to track this down, I'd put a breakpoint where the delete is =

invoked, then I'd

do a lot of instruction-level single stepping to make sure that the objec=

t was actually

being deleted.

I'm curious why you titled this an "STL" string leak, since I do not see =

a single instance

of std::string anywhere in the code.

I hope it is clearer now...

In addition, it may be a leak (odd though it may be) in the COleDateTime:=

:Format handler;

so you need to check the CString that is returned, and look at its data p=

ointer. Then

compare that data pointer to the one that is claimed as a leak. If the=

y are not the same,

then it is not that string. Now the mystery is: where did that string =

come from.

Note that in the leak message, there is a {count} given. If, when runn=

ing this program,

you can exactly replicate this message with the same {count} (which ideal=

ly should happen

if you do exactly thesame things in exactly the same order), then you can=

 tell the

storage allocator to break on that allocation sequence number, and find o=

ut who really

allocated that string.

I note that the location of the allocation is not given as strcore.cpp, w=

hich would be

true if this really were the CString. So it looks like it is being all=

ocated from

somewhere else.

So it is probably really not the CString...

If you write a file which does not come from the MFC wizards, make sure y=

ou find the

#define new DEBUG_NEW

line in some other file and copy it, along with all its conditionals, to =

your own file;

this will allow allocation tracking to be more effective. You may also=

 need to copy the

this_file definition.

I added

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW

to all of my files now. But how should it help me? because at least at
the leak message I don't see any extra information.


If instead all the above I will put

   CString sNow = "a"

and then I'll cast - there is no leak!


Joseph M. Newcomer [MVP]
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