/**********************************************************************
 * fileopen.cc
 * Tom Kelliher
 *
 * This program demonstrates how to open a file whose name isn't known
 * until runtime.  Two file are opened, one for reading and one for
 * writing.  The files are immediately closed (no I/O is done).
 **********************************************************************/


#include <iostream.h>
#include <fstream.h>


const int NAME_LEN = 80;


// Prototypes.
int queryOpen(const char*, fstream&, int);


/**********************************************************************
 * main
 **********************************************************************/

int main()
{
   fstream f1, f2;   // Two files.  Note that they're fstream, not
                     // ifstream nor ofstream.

   // Open files and check for success.
   if (!queryOpen("Input file to open: ", f1, ios::in))
      cout << "f1 failed\n";

   if (!queryOpen("Output file to open: ", f2, ios::out))
      cout << "f2 failed\n";

   /* We could begin doing things like:
   f1 >> i;
   f1.getline(char_array, length);
   f2 << "Hello world!\n";
   */

   f1.close();
   f2.close();

   return 0;
}


/**********************************************************************
 * queryOpen --- Print a message, read a filename to open from cin and
 *               try to open it.
 * mesg: A string to print before reading the filename from cin.
 * f: The fstream variable to which to bind the file.
 * mode: ios::in to open for reading, ios::out for writing, etc.
 *
 * return value: 1 if successful in opening the file, 0 otherwise.
 **********************************************************************/

int queryOpen(const char* mesg, fstream& f, int mode)
{
   char name[NAME_LEN];

   cout << mesg;
   cin.getline(name, NAME_LEN);   // Read filename.
   f.open(name, mode);
   return !f.fail();
}