your
text
would
be
entered
like
this

youway exttay ouldway ebay enteredway ikelay histay

your text would be entered like this

std::string in;
while (std::cin >> in)
  std::cout << piglatin(in) << char(std::cin.get());

#include <cctype>
char look_for_nl(std::istream& is) {
  for (char d = is.get(); is; d = is.get()) {
    if (d == 'n') return d;
    if (!isspace(d)) {
      is.putback(d);
      return ' ';
    }
  }
  // We got an eof and there was no NL character. We'll pretend we saw one
  return 'n';
}

std::string in;
while (std::cin >> in)
  std::cout << piglatin(in) << look_for_nl(std::cin);