eof(), bad(), good() functions aren't detected by autocomplete

问题

This code block:

#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main () {
  string line;
  ifstream myfile ("example.txt");
  if (myfile.is_open())
  {
    while ( myfile.good() )
    {
      getline (myfile,line);
      cout << line << endl;
    }
    myfile.close();
  }

  else cout << "Unable to open file"; 

  return 0;
}

taken from here, compiles and runs well, but the good() function isn't recognized by my IDE (Qt) when I try to write it by hand and use autocomplete. Can anyone tell me why?

Thank you

P.S. I use the mingw compiler, if that helps.

来源：https://stackoverflow.com/questions/16569651/eof-bad-good-functions-arent-detected-by-autocomplete