couple of questions concerning Boost::scoped_ptr

hello all , today i was reading a boost tutorial and there i faced scoped_ptr and the likes . i faced some issues which i would like to discuss with you .
first of all consider this little bit of code:

Code:

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#include <boost/scoped_ptr.hpp>

int main()
{
    boost::scoped_ptr<int> i(new int);
    *i = 1;
    *i.get() = 2;
    std::cout<<"?= "<<i<<" The Address= "<< i.get() <<"\t The Value= "<<*i.get();
    i.reset(new int);
}

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and the output is (e.g):

Code:

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?=        The Address=0x311018  The Value=2

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First question:
Why is the out of i empty? is it not supposed to print out the address of the object which i is referring to ?
Second question :
What exactly get() method do ? is it s getter? or a setter ?
if it gets sth where does it put it ?
i tried the following code :

Code:

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std::cout<<"\t OutPut5= "<<(*i.get()=5) <<"\t OutPut2= "<<*i.get();

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output:

Code:

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OutPut5= 5    OutPut2= 2

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what is happening here? :confused: what happened to that 5?
Third question :
Why is it said that we can not use scoped_ptr with arrays ?
why exactly did they divided this pointer class into two separate classes ?
well couldn't they just use an if statement to find out what we are dealing with at runtime ? and if it were an array use that delete[] operator ?
aside form that what is the crucial difference between delete and delete[] ?

and my forth question :
what is the operator bool() ? concerning these pointers ? whats the use of it ? and how to use it ?

Quote:

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Originally Posted by Masterx

Why is the out of i empty? is it not supposed to print out the address of the object which i is referring to ?

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Looking at the documentation, operator<< is not overloaded, so what you are getting is the result of using the smart pointer in an unintended fashion. Effectively, it is "undefined behaviour" with respect to the library.

Quote:

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Originally Posted by Masterx

What exactly get() method do ?

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It returns the internal pointer.

Quote:

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Originally Posted by Masterx

is it s getter? or a setter ?

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It is a getter.

Quote:

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Originally Posted by Masterx

if it gets sth where does it put it ?

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What do you mean? It just returns a value.

Quote:

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Originally Posted by Masterx

what is happening here? what happened to that 5?

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The order of evaluation of function arguments is unspecified, so you should not be doing this in the first place.

Quote:

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Originally Posted by Masterx

Why is it said that we can not use scoped_ptr with arrays ?

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Because the deleter is not for arrays.

Quote:

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Originally Posted by Masterx

well couldn't they just use an if statement to find out what we are dealing with at runtime ? and if it were an array use that delete[] operator ?

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No, though the approach used by std::unique_ptr is to allow for a custom deleter to be specified, and then specialise this for array types.

Quote:

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Originally Posted by Masterx

aside form that what is the crucial difference between delete and delete[] ?

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One is for lone objects and the other for arrays.

Thanks laiserlight .
would you answer my forth question ?

Quote:

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and my forth question :
what is the operator bool() ? concerning these pointers ? whats the use of it ? and how to use it ?

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It is so that you can use it like:

Code:

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if (p)

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can somepne expalin to me , what this notation is for ? and what it does? and what is its other equivalents?

Code:

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boost::shared_ptr<int> *sh = static_cast<boost::shared_ptr<int>*>(p);

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it really looks weird to me , never seen it anywhere

What notation? The static_cast?

Anyway, it seems rather unnecessary to have a pointer to a shared_ptr.