C++ iterators & loop optimization

Question

I see a lot of c++ code that looks like this:

for( const_iterator it = list.begin(),
     const_iterator ite = list.end();
     it != ite; ++it)

<

Answer 1

I would choose the option that is most concise and readable. Don't try to second guess the compiler and the optimisations it might perform. Remember that the vast majority of your code will have absolutely no effect on overall performance, so only if this is in a performance critical section of code should you spend the time to profile it and choose an appropriately efficient source representation.

With specific reference to your example, the first version makes a copy of the end() iterator, invoking whatever code runs for the copy constructor of the iterator object. STL containers generally contain inline end() functions, so the compiler has plenty of opportunity to optimise the second version even if you're not trying to help it out. Which one is best? Measure them.