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buffer overrun?

Posted on 2011-09-21
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Last Modified: 2012-05-12
Hi Experts,

I have a class that contains this member:

vector<CSomeClass> m_Member;

When I look at the address of m_Member before some work is done, and then after, the address is different.  Is there a way to stop execution of whatever thread is currently running as soon as the contents of the address of this member changes?  I noticed there's a new data breakpoint that can be added in VS2010, but it doesn't stop execution when the variable changes - and I don't want control to have to flow over a line that contains that breakpoint- I want that breakpoint to be program-wide.

Thanks for any help!
Mike
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Question by:thready
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3 Comments
 
LVL 40

Accepted Solution

by:
evilrix earned 250 total points
ID: 36578700
You can set conditional break points in Visual Studio's debugger.
http://msdn.microsoft.com/en-us/library/7sye83ce.aspx

When you say the address has changed -- are you sure you're not looking at the internal pointer that the vector is likely to be using to address its internal buffer? This, of course, may change if the internal buffer is re-allocated.
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LVL 34

Assisted Solution

by:sarabande
sarabande earned 250 total points
ID: 36581491
to add to above comment:

the address of a member cannot change beside the class object which the member belongs to changes.

class A
{
public:
    std::vector<B> v;
};

void C::f()
{
     // create A object on the heap
     A * pa = new A;   
     // get pointer to vector member of A object pA is pointing to
     std::vector<B> * pabv = &pa->v;
     // the value of pabv pointer now is address of vector member
     pa->v.push_back(B());   
     pabv->resize(10, B());
     // the address of pa->v will not change by operations you do on the vector
     if (&pa->v != pabv)
     {
          // never comes here
     }
     pa = new A;  // create new A 
     // now pa->v has new address cause the A object is not the same as before
}

Open in new window


all other possibilities would mean that memory was corrupted somehow.

Sara
0
 
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Author Closing Comment

by:thready
ID: 36926570
Thank you!
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