Re: In map iterator is there a difference between (*iter).second and iter->second?

"Jim Langston" <>
Wed, 20 Aug 2008 00:13:14 -0700

Re: In map iterator is there a difference between (*iter).second and

"puzzlecracker" <> wrote in message

I see that a lot of former in the code, and wonder if there is a
technical reason for that

Most people suggest the second form, iter->second, which I initially used.
But then I ran across this from some class I was developing:


#include "Observer.h"
#include <set>

class Observable {
    std::set<Observer*> observers;
    virtual void addObserver(Observer& o) {
    virtual void deleteObserver(Observer& o) {
    virtual void deleteObservers() {
    virtual size_t countObservers() {
        return observers.size();
    virtual void notifyObservers(Argument* arg = NULL)
        std::set<Observer*>::iterator it;
        for(it = observers.begin(); it != observers.end(); it++)
           (*it)->update(this, arg);


Look at the function virtual void notifyObservers(Argument* arg = NULL)
specifically at the line:
        (*it)->update(this, arg);

When I first tried to code that I was trying to do:
it->->update(this, arg);
which, obviously, wouldn't compile. So I wound up with that format,
derefernce the iterator, then use the arrow operator. And I thought about
it, and dereferenceing the iterator would always work, where using the arrow
operator would usually work, but not always. So I determined that all code
working with iterators would be dereferecned instead of using the arrow
operator for consistancy. So a map would be

I know seeing (*it) in my code that I am dereferncing an iterator. In fact,
I reserve the variable it for a local iterator.

Other than that, there is no real difference, it comes down to personal
prefernce and whatever your workplace standards are. I figured on (*it)
because I could be consistant with it. Although it is said that consistancy
is the hobgoblin of little minds I still like being consistant if I can. If
that means I have a little mind, so be it.


Little Minded Jim Langston

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