multiple numbers input on one line

Question

I want to know how I can accept multiple numbers on one line without exactly knowing in advance how many.

So for example if I have 1 2 3 4 as input I could

Answer 1

main.cc

#include 
#include 
#include 
#include 
#include 

int main() {
    std::vector vec;

    std::string line;
    if(!std::getline(std::cin, line)) return 1;
    std::istringstream iss(line);

    std::copy(std::istream_iterator(iss),
        std::istream_iterator(),
        std::back_inserter(vec));

    std::copy(vec.begin(), vec.end(), std::ostream_iterator(std::cout, ", "));

    return 0;
}

stdin

1 2 3 4 5

stdout

1, 2, 3, 4, 5,

https://ideone.com/FHq4zi