Iterator Problem (Printing the address problem)... Help

[shong9]

Hello,

I am newbie to the topic of iterators. I need to know how many iterations the following "for loop" will execute. Iterators are used.

aend = m_SampleA.end();
for (aiter=m_SampleA.begin(), aiter!=aend, ++aiter)
{
...
}

The compile error comes up when I tried to print the address,
printf("address = %p\n", m_SampleA.begin())

Also, I have no idea what is the memory separation between iterator increments.. so I have difficulty finding the number of iterations...

Is there any special function that returns the address ?

Thank you

 

[cpjust]

printf("address = %p\n", m_SampleA.begin())

What makes you think an iterator is a pointer?

Assuming no objects are inserted or deleted in the for loop, I would guess it would run m_SampleA.size() iterations.

 

[uolj]

As cpjust alluded to, a pointer and an iterator are different. To get a pointer from an iterator, use:

&(*aiter)

although I don't see the need for doing that.

 

[ArkM]

An iterator is an object (or a type, if you wish which has its own operator* return an object of type T for which operator& is defined and returns a pointer to T. It looks like a pointer in this aspect (and has incr/decr and -> ops too) but it's not a pointer.

So (by definition if aiter is an iterator (of any kind) then *aiter returns an object and &*aiter returns a pointer to this object.

 

[jstreich]

[quote[
I am newbie to the topic of iterators. I need to know how many iterations the following "for loop" will execute. Iterators are used.

aend = m_SampleA.end();
for (aiter=m_SampleA.begin(), aiter!=aend, ++aiter)
{
...
}
[/quote]

int i = 0;
aend = m_SampleA.end();
for (aiter=m_SampleA.begin(), aiter!=aend, ++aiter)
{
  std::cout << i++ <<end;
}

The compile error comes up when I tried to print the address,
printf("address = %p\n", m_SampleA.begin())

This has already been answered. BTW, why printf and not cout.

std:cout << "address = " << m_SampleA.begin() <<endl;
_should_ (IIRC) print the address of m_SampleA.begin() which will be the same address &m_SampleA which will always be the same while m_SampleA is in scope.

Also, I have no idea what is the memory separation between iterator increments.. so I have difficulty finding the number of iterations...

Why not just count them, or get the size of the m_SampleA using m_SampleA.size() if m_SampleA is a STL container like vector, map, list, etc.

Is there any special function that returns the address ?

uolj had the answer to this one. But are you looking for the address of the iterator or the address of the object to which it points?

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