Performance of pIter != cont.end() in for loop

Question

I was getting through \"Exceptional C++\" by Herb Sutter lately, and I have serious doubts about a particular recommendation he gives in Item 6 - Temporary Objects.

Answer 1

If you really need the performance, you let your shiny new C++11 compiler write it for you:

for (const auto &i : emps) {
    /* ... */
}

Yes, this is tongue-in-cheek (sort of). Herb's example here is now out of date. But since your compiler doesn't support it yet, let's get to the real question:

Is this a kind of construction I could rely on a compiler to optimize?

My rule of thumb is that the compiler writers are way smarter than I am. I can't rely on a compiler to optimize any one piece of code, because it might choose to optimize something else that has a bigger impact. The only way to know for sure is to try out both approaches on your compiler on your system and see what happens. Check your profiler results. If the call to .end() sticks out, save it in a separate variable. Otherwise, don't worry about it.