Should a range for loop be used instead of iterators on a vector?

Question

Given a vector, vc, one can iterate through the vector with a range for:

for (auto c : vc)
    std::cout << c;

Or with an iterator:

for (auto it = vc.cbegin(); it != vc.cend(); ++it)
    std::cout << *it;

Is there a functional reason to use one method over the other, or is this merely a matter of style?

Answer 1

From the performance point of view there isn't really a difference. As Bjarne Stroustrup writes in his book the C++ Programming language 4th edition:

The simplest loop is a range- for -statement; it simply gives the programmer access to each element of a range.

As a fan of the KISS principle I tend to prefer simpler constructs over more complex ones. However, it really boils down to what you want to achieve. From the same book Bjarne reveals why a range-for loop is designed to be simple:

Note that a range- for loop is a deliberately simple construct. For example, using it you can’t touch two elements at the same time and can’t effectively traverse two ranges simultaneously. For that we need a general for-statement.

Consequently, there are contexts that you can't use a range-for loop and you have to reside to the classical for-statement.

Bottom line use range-for loop when ever possible because is simpler and more readable.

Answer 2

It is more or less a matter of style, but consider it this way; range-for loops are more concise than explicit iterator usage. The less code you write, the less places where things can go wrong.