Re: random access iterator

"Alexander Nickolov" <>
Mon, 3 Mar 2008 14:39:15 -0800
Well, it can be useful for example when writing bubble-sort
by hand (not that I'd actually advocate doing that...):

bool bSwap = false;
while (did_swap) {
    bSwap = false;
    for (range_type::iterator it = range.begin(); it != range.end() && it+1
!= range.end(); ++it) {
        if (*it > it[1]) {
            std::swap(*it, it[1]);
            bSwap = true;

The important point is about accessing elements relative to the current
position of the iterator, not the bubble-sort algorithm of course... :)

Alexander Nickolov
Microsoft MVP [VC], MCSD

"Abhishek Padmanabh" <> wrote in message

"George" <> wrote in message

For random access iterator, operator[] is supported. Mentioned in
book, Chapter 19 (Iterators and Allocators).

I have not used operator[] on random access iterator before and I have
found a good and simple sample either. :-)

That is because it is not very intuitive to use as compared to using the
operator[] overloaded for the container itself. Also, as far as VC++ 2005
is concerned, it causes two dereferences. You can use the iterator's
operator[] as below:

using std::vector;
int main()
 vector<int> vec(10);
 vector<int>::iterator it = vec.begin();
 int fifth_element = it[4]; //equivalent to advance it by 4 and
dererefence the resulting iterator
 int fifth_element = vec[4]; //preferred and more intuitive

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