Range-based loop over an input stream

Question

To iterate over an input stream, we would usually use a std::istream_iterator like so:

typedef std::istream_iterator input_iterato         


        

Answer 1

Here is one possible solution. Sadly, it does require an extra structure:

#include 
#include 
#include 
#include 
#include 

struct S {
  std::istream& is;
  typedef std::istream_iterator It;
  S(std::istream& is) : is(is) {}
  It begin() { return It(is); }
  It end() { return It(); }
};

int main () {
  std::ifstream file("myfile");
  for(auto& string : S(file)) {
    std::cout << string << "\n";
  }
}

Another solution is to derive from std::ifstream:

#include 
#include 
#include 
#include 
#include 


struct ifstream : std::ifstream {
  // using std::ifstream::ifstream; I wish g++4.7 supported inheriting constructors!
  ifstream(const char* fn) : std::ifstream(fn) {}
  typedef std::istream_iterator It;
  It begin() { return It(*this); }
  It end() { return It(); }
};

int main () {
  ifstream file("myfile");
  for(auto& string : file) {
    std::cout << string << "\n";
  }
}