//
// This is example code from Chapter 10.10 "A standard input loop" of
// "Programming -- Principles and Practice Using C++" by Bjarne Stroustrup
//

#include "std_lib_facilities.h"

//------------------------------------------------------------------------------

typedef int My_type;

//------------------------------------------------------------------------------

void input_loop_1(istream& ist)
{  
   for (My_type var; ist>>var; ) { // read until end of file
      // maybe check that var is valid
      // do something with var
   }
   // we can rarely recover from bad; don't try unless you really have to:
   if (ist.bad()) error("bad input stream");
   if (ist.fail()) {
      // was it an acceptable terminator?
   }
   // carry on: we found end of file
}

//------------------------------------------------------------------------------

void input_loop_2(istream& ist)
{  
   for (My_type var; ist>>var; ) { // read until end of file
      // maybe check that var is valid
      // do something with var
   }
   if (ist.fail()) { // use '|' as terminator and/or separator
      ist.clear();
      char ch;
      if (!(ist>>ch && ch=='|')) error("bad termination of input");
   }
   // carry on: we found end of file or a terminator
}

//------------------------------------------------------------------------------

void end_of_loop(istream& ist, char term, const string& message)
{
   if (ist.fail()) { // use term as terminator and/or separator
      ist.clear();
      char ch;
      if (ist>>ch && ch==term) return;    // all is fine
      error(message);
   }
}

//------------------------------------------------------------------------------

void input_loop_3(istream& ist)
{  
   for (My_type var; ist>>var; ) { // read until end of file
      // maybe check that var is valid
      // do something with var
   }
   end_of_loop(ist,'|',"bad termination of file");    // test if we can continue
   // carry on: we found end of file or a terminator
}

//------------------------------------------------------------------------------

int main()
   try
      {
         input_loop_3(cin);
         input_loop_2(cin);
         input_loop_1(cin);
         // Somewhere: make ist throw an exception if it goes bad:
         cin.exceptions(cin.exceptions()|ios_base::badbit);
      }
   catch (exception& e) {
      cerr << "error: " << e.what() << '\n'; 
      return 1;
   }
   catch (...) {
      cerr << "Oops: unknown exception!\n"; 
      return 2;
   }

//------------------------------------------------------------------------------