// FILE: CopyFile.cpp
// COPIES FILE IN_DATA.DAT TO FILE OUT_DATA.DAT

#include <stdlib.h>	// for the definition of EXIT_FAILURE
				//    and EXIT_SUCCESS
#include <fstream.h>	// required for external file streams

// ASSOCIATE PROGRAM IDENTIFIERS WITH EXTERNAL FILE NAMES
#define in_file "in_data.dat"
#define out_file "out_data.dat"

// Functions used ...
// COPIES ONE LINE OF TEXT
int copy_line
      (ifstream&,		// IN: infile stream
       ofstream&);		// OUT: outfile stream

int main()
{
   // Local data ...
   int line_count;		// output: number of lines processed
   ifstream ins;		// associates ins as an input stream
   ofstream outs;		// associates outs as an output stream

   // Open input and output file, exit on any error.
   ins.open (in_file);	// ins connects to file in_file
   if (ins.fail ())
   {
      cerr << "*** ERROR: Cannot open " << in_file
           << " for input." << endl;
      return EXIT_FAILURE;	// failure return
   }  // end if

   outs.open (out_file);		// outs connects to file out_file
   if (outs.fail ())
   {
      cerr << "*** ERROR: Cannot open " << out_file
           << " for output." << endl;
      ins.close ();
      return EXIT_FAILURE;	// failure return
   }  // end if

   // Copy each character from in_data to out_data.
   line_count = 0;
   if (copy_line (ins, outs) != 0) line_count++;

   while (!ins.eof ())
      if (copy_line (ins, outs) != 0) line_count++;

   // Display a message on the screen.
   cout << "Input file copied to output file." << endl;
   cout << line_count << " lines copied." << endl;

   ins.close ();			// close input file stream
   outs.close ();			// close output file stream
   return EXIT_SUCCESS;	// successful return
}

// COPY ONE LINE OF TEXT FROM ONE FILE TO ANOTHER
int copy_line
   (ifstream& ins,		// IN: ins stream
    ofstream& outs)		// OUT: outs stream
// Pre:     ins is opened for input and outs for output.
// Post:    Next line of ins is written to outs.
//          The last character processed from ins is <nwln>;
//          the last character written to outs is <nwln>.
// Returns: The number of characters copied.

{
   // Local data ...
   const char nwln = '\n';		// newline character
   char next_ch;				// inout: character buffer
   int char_count = 0;			// number of characters copied

   // Copy all data characters from ins file stream to outs file
   //    stream.
   ins.get (next_ch);
   while ((next_ch != nwln) && !ins.eof())
   {
      outs.put (next_ch);
      char_count++;
      ins.get (next_ch);
   }  // end while

   // If last character read was nwln write it to out_data.
   if (!ins.eof ())
   {
      outs.put (nwln);
      char_count++;
   }
   return char_count;
}  // end copy_line