Printing lists with commas C++

Question

I know how to do this in other languages, but not C++, which I am forced to use here.

I have a Set of Strings that I\'m printing to out in a list, and they need a co

Answer 1

There are lots of clever solutions, and too many that mangle the code beyond hope of salvation without letting the compiler do its job.

The obvious solution, is to special-case the first iteration:

bool first = true;
for (auto const& e: sequence) {
   if (first) { first = false; } else { out << ", "; }
   out << e;
}

It's a dead simple pattern which:

1. Does not mangle the loop: it's still obvious at a glance that each element will be iterated on.
2. Allows more than just putting a separator, or actually printing a list, as the else block and the loop body can contain arbitrary statements.

It may not be the absolutely most efficient code, but the potential performance loss of a single well-predicted branch is very likely to be overshadowed by the massive behemoth that is std::ostream::operator<<.