/*
   testfile3.cpp
   CIS 150
   6/2/2005
   David Klick
   
   This program demonstrates the use of a repetition
   construct to read a file of unknown length.
*/

#include <iostream>
#include <fstream>
using std::cout;
using std::ofstream;
using std::ifstream;

int main(void) {
   int n;

   // open a file for writing
   cout << "Opening output file\n";
   ofstream outfile("datafile3.txt");
   
   // display error and exit if file didn't open
   if (!outfile) {
      cout << "Error: could not open output file.\n";
      return 1;
   }
   
   // write some data out to file
   cout << "Writing data to file\n";
   for (n=11; n<40; n=n+2) {
      outfile << n << '\n';
   }
   
   // done processing - close file
   outfile.close();
   cout << "File created\n";

   // open the file we created for reading
   cout << "Opening input file\n";
   ifstream infile("datafile3.txt");
   
   // display error and exit if file didn't open
   if (!infile) {
      cout << "Error: could not open input file.\n";
      return 2;
   }
   
   // read all data from the file and display it
   //   - a loop is used here because the number of
   //     records to be read is unknown
   //   - notice the use of a priming read
   cout << "Reading data from file\n";
   infile >> n;
   while (!infile.eof()) {
      cout << n << '\n';
      infile >> n;
   }
   
   // done processing - close file
   infile.close();
   cout << "Program done\n";
   
   return 0;
}