Boost shared_ptr question

[ekhule]

Hello all,

I have a class called Wheel, and I created a boost shared_ptr to this class in the following way:

typedef boost::shared_ptr<Wheel> WheelPtr;

I also have a vector of these shared_ptr's to Wheels as so:

vector<WheelPtr> wheels;

In the wheel class I have a variable called "flat" which is initialized to true.

I have one thread that keeps iterating through the list looking for flat wheels like so:

vector<WheelPtr>::iterator it;
for(it=wheels.begin(); it!=wheels.end();)
{
     if(!(*it)->Flat())
     {
       (*it) = WheelPtr(); // set to NULL here
        it=wheels.erase(it);
     }
     else
          it++;
}

In another thread I am constantly doing something else to the wheels. What I have noticed is that when I execute the line:

       (*it) = WheelPtr(); // set to NULL here

in the debugger the handle is 0x00000000. But in my other thread the handle is something else like 0x00104f08.

Why is the shared_ptr not NULL in the other thread?

Regards,
Ellay K.