c++ - C++11 cin input validation -

what best way in c++11 (ie. using c++11 techniques) validate cin input? i've read lots of other answers (all involving cin.ignore, cin.clear, etc.), methods seem clumsy , result in lots of duplicated code.

edit: 'validation', mean both well-formed input provided, , satisfies context-specific predicate.

i'm posting attempt @ solution answer in hopes useful else. not necessary specify predicate, in case function check well-formed input. am, of course, open suggestions.

//could use boost's lexical_cast, throws exception on error, //rather taking reference , returning false. template<class t> bool lexical_cast(t& result, const std::string &str) {     std::stringstream s(str);     return (s >> result && s.rdbuf()->in_avail() == 0); }  template<class t, class u> t promptvalidated(const std::string &message, std::function<bool(u)> condition = [](...) { return true; }) {     t input;     std::string buf;     while (!(std::cout << message, std::getline(std::cin, buf) && lexical_cast<t>(input, buf) && condition(input))) {         if(std::cin.eof())             throw std::runtime_error("end of file reached!");     }     return input; } 

here's example of usage:

int main(int argc, char *argv[]) {     double num = promptvalidated<double, double>("enter number: ");     cout << "the number " << num << endl << endl;      int odd = promptvalidated<int, int>("enter odd number: ", [](int i) { return % 2 == 1; });     cout << "the odd number " << odd << endl << endl;     return 0; } 

if there's better approach, i'm open suggestions!