How about this:
#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <string>
#include <sstream>
int main()
{
std::vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
v.push_back(5);
std::ostringstream ss;
if(!v.empty()) {
std::copy(v.begin(), std::prev(v.end()), std::ostream_iterator<int>(ss, ", "));
ss << v.back();
}
std::cout << ss.str() << "\n";
}
No need to add extra variables and doesn’t even depend on boost! Actually, in addition to the “no additional variable in the loop” requirement, one could say that there is not even a loop 🙂