Detecting a container's end

[greve]

I'm used to scan through a container in a fashion like this:

vector<int> Data;
...
for (
  vector<int>::iterator Val= Data.begin();
  Val != Data.end();
  ++Val
  )
  {...}

I now saw in some other guy's code something similar but using operator< instead of !=. The code is working as expected but I doubt whether this is a safe alternative (because it's unlikely that all elements of the container will be in successive order).
Thanks for any comments!

[laserlight]

I now saw in some other guy's code something similar but using operator< instead of !=. The code is working as expected but I doubt whether this is a safe alternative (because it's unlikely that all elements of the container will be in successive order).

It is a safe alternative for std::vector because the iterators of a std::vector are random access iterators, and operator< is available for random access iterators. However, it also means that the code will not work for say, forward iterators, which would be a shame if forward iterators will do.

[monarch_dodra]

!= Works for ALL flavors of iterators, no exceptions. [EDIT: Higher than output iterator]

< Works ONLY for RA iterators. At best, it < is no faster than !=, but can be slower....

Just like the i++ vs ++i debate, You are better of just using the more efficient !=, unless you have a very specific reason not to.

[laserlight]

!= Works for ALL flavors of iterators, no exceptions.

Output iterators are an exception.

[monarch_dodra]

..Forgot about those output iterators....

[nuzzle]

I'm used to scan through a container in a fashion like this:

A simple scan over just about anything can be done in a highlevel way using "foreach". It's coming in the new C++ standard but in the meantime one can use BOOST_FOREACH,

http://www.boost.org/doc/libs/1_47_0...l/foreach.html

[monarch_dodra]

A simple scan over just about anything can be done in a highlevel way using "foreach". It's coming in the new C++ standard but in the meantime one can use BOOST_FOREACH,

http://www.boost.org/doc/libs/1_47_0...l/foreach.html

I personally avoid boost's for each: It doesn't actually bring any functionality, apart from prettier syntax, via some very hackish macro/template. Have you ever looked at the output of the processor after a FOREACH? It is a legit 30 solid lines of templates. Sure, the compiler inlines it all away, but still...

I've found that the good old fashion std::for_each works just as well, and can actually improve your program by more than just pretty syntax.

[nuzzle]

I personally avoid boost's for each: It doesn't actually bring any functionality, apart from prettier syntax, via some very hackish macro/template. Have you ever looked at the output of the processor after a FOREACH? It is a legit 30 solid lines of templates. Sure, the compiler inlines it all away, but still...

I've found that the good old fashion std::for_each works just as well, and can actually improve your program by more than just pretty syntax.

Most modern languages have a built-in foreach statement and so does C++11.

http://en.wikipedia.org/wiki/Foreach_loop

This means the Boost foreach will be somewhat sidestepped in the future. In think the Boost foreach has been a good substitute for a native foreach though. Template code has a tendency to be ugly and especially when automatically generated but who cares really. You don't have to torture yourself by looking at it. Boost foreach is efficient and offers a higher abstraction level and that's what counts to me. I leave the peeking into implementations behind the curtain to pervert masochists.

Should you use the C++11 foreach? I certainly will. In my view one should seek the highest abstraction level that's readily available. It's a sure way to improve a program. For the same reason I'm also going to use for example C++11 lambdas.

[laserlight]

I've found that the good old fashion std::for_each works just as well, and can actually improve your program by more than just pretty syntax.

I prefer to use more specific algorithms where applicable. I think std::for_each would be more useful with lambda functions. The thing is, although lambda functions have been introduced with C++11, the range based for loop makes this std::for_each + lambda function combination rather redundant for typical usage.