simple question - another way

[l2u]

Hello

I have:

std::list<std::string> _list;
std::list<std::string>::iterator it = _list.begin();

How can I write this in one line:

++it;
if (it == list.end()) { it = list.begin(); }

something like:

it = (it == list.end()) ? list.begin() : ++it;

will make it crash when it comes to the end of list..

Thanks for help

[AverageSoftware]

something like:

it = (it == list.end()) ? list.begin() : ++it;

will make it crash when it comes to the end of list..

If I'm understanding your problem correctly...

if (++it == list.end()) it = list.begin();

Incidentally, you shouldn't start identifier names with underscores. Those are generally reserved for the compiler's internal use.

[Desolation]

Why try to make it shorter ? Shorter code, in this situation, yields only more errors. The problem occurs because pre-increment and post-increment have a higher operator precedence than the if-else ternary operator ? : . You want to use it += 1. I advise you to use the longer version though. It is much easier to read. Also try indenting your code more (2 braces on a single line.. *sigh*) and try not to use underscores before a variable name, as they are reserved for the implementor, if I remember.

[CrazyNorman]

Not to start a flamewar or anything, but I'd argue that it++ is easier to read, and to any experienced C/C++ programmer, makes it clear that it is an increment, as opposed to a simple multiple of 1 that might be changed to 2 or 3 at another time. As for putting it all in one line, perhaps that is not the best idea.

[swoopy]

if (++it == list.end()) it = list.begin();
Seems readable.

[CornedBee]

+= 1 doesn't work for std::list iterators anyway.

What is the exact problem you want to solve? I find none of the snippets posted so far readable.

[Daved]

++it;
if (it == list.end()) { it = list.begin(); }

and

it = (it == list.end()) ? list.begin() : ++it;

do two different things. One increments before the check against end(), the other increments after.

I prefer:

if (++it == list.end())
    it = list.begin();

or

if (it == list.end())
    it = list.begin();
++it;

depending on which you meant to do.

[l2u]

Is there any way to check if interator has higher operator precedence (if it is bad)?

[CornedBee]

iterators aren't operators, therefore they have no precedence.

You can look up the iterator precedences in your favourite C++ reference. They cannot be changed, and new iterators cannot be defined.