std::basic_ios::good

// error state flags
#include <iostream>     // std::cout, std::ios
#include <sstream>      // std::stringstream
void print_state (const std::ios& stream) {
  std::cout << " good()=" << stream.good();
  std::cout << " eof()=" << stream.eof();
  std::cout << " fail()=" << stream.fail();
  std::cout << " bad()=" << stream.bad();
}
int main () {
  std::stringstream stream;
  stream.clear (stream.goodbit);
  std::cout << "goodbit:"; print_state(stream); std::cout << '\n';
  stream.clear (stream.eofbit);
  std::cout << " eofbit:"; print_state(stream); std::cout << '\n';
  stream.clear (stream.failbit);
  std::cout << "failbit:"; print_state(stream); std::cout << '\n';
  stream.clear (stream.badbit);
  std::cout << " badbit:"; print_state(stream); std::cout << '\n';
  return 0;
}