how to read command output line by line in gcc in windows just as with the standard input?

This is what I tried:

#include <iostream>
#include <string>

int main(int argc, char const *argv[]) {
  using namespace std;
  for (string cin_line; getline(cin, cin_line);) {
    cout << cin_line << endl;
  }
  FILE* pipe = popen("app.exe", "r");
  for (string result_line; getline(pipe, result_line);) {
    cout << result_line << endl;
  }
  pclose(pipe);
  return 0;
}

It doesn't compile, the result is:

no matching function for call to 'getline(FILE*&, std::__cxx11::string&)'

Second example I've found here: http://ift.tt/1C7QKcz But it seems mingw doesn't have pstream included: fatal error: pstream.h: No such file or directory

I know how to do it using buffer and get whole output on single line (like here: http://ift.tt/1OZ1l3q ) then explode the line by \n and get my array, but the point here is that I must provide the output as soon as the input comes in.

Also I tried example from here: http://ift.tt/1C7QKsQ - I've added main function to that:

#include <cstdio>
#include <iostream>
#include <string>

int main(int argc, char const *argv[]) {
  using namespace std;
  FILE * fp ;

  if((fp= popen("/bin/df","r")) == NULL) {
      // error processing and exit
  }
  ifstream ins(fileno(fp)); // ifstream ctor using a file descriptor

  string s;
  while (! ins.eof()){
      getline(ins,s);
      // do something
  }  
  return 0;
}

This also doesn't compile:

error: variable 'std::ifstream ins' has initializer but incomplete type ifstream ins(fileno(fp)); // ifstream ctor using a file descriptor