///////////////////////////////////////////////////////////////
// filebuf.cpp                                               //
//   demonstrate low level input and output using filebufs   //
//   built from FILE pointer and stdout                      //
//                                                           //
// Jim Fawcett, 24 Mar 96, modified 23 Mar 97                //
///////////////////////////////////////////////////////////////

#include <iostream.h>    // cout, <<
#include <fstream.h>     // ifstream(), <<, >>

// note:  will not compile with the modern version given below
//        I believe that is a defect with VC 6.0 fstream
//
// #include <iostream>
// #include <fstream>
// using namespace std;

#include <cstdlib>       // exit(1);
#include <cstdio>        // fopen(), FILE
#include <string>

//----< display titles >---------------------------------------

void title(const char *t, char ul = '-', ostream &out = cout) {

  int len = strlen(t) + 2;
  std::string line(len,ul);
  if(ul == '=')
    out << "\n " << line.c_str();
  out << "\n  " << t
      << "\n " << line.c_str() << endl;
}

//----< begin demonstration >----------------------------------

void main(int argc, char *argv[]) {

  //////////////////////////////////////////////////////////////
  title("Demonstrating use of Custom Buffers with File IO",'=');
  //////////////////////////////////////////////////////////////

  if(argc < 2) {
    cout << "\nplease enter name of text file on command line\n";
    exit(1);
  }

//

  title("using custom buffer for input from file");
  /////////////////////////////////////////////////

  FILE *fptr = fopen(argv[argc-1],"r");
  if(!fptr) {
    cout << "can't open file " << argv[argc-1] << endl;
    exit(1);
  }

  // build an input filebuf using custom input buffer and
  // file opened with stdio::fopen()

  const int bufSize = 256;
  char inbuf[bufSize];               // make custom buffer
  int handle = fileno(fptr);         // get file handle for filebuf
  filebuf ifb(handle,inbuf,bufSize); // construct filebuf
  cout << &ifb << endl;              // stream to cout
  cout.flush();

  // build an output filebuf using custom output buffer and
  // stdio::stdout then attach to stream and fill from
  // input buffer defined above

  title("using custom buffer for stdout");
  ////////////////////////////////////////

  char outbuf[bufSize];              // custom buffer
  filebuf ofb(1,outbuf,bufSize);     // attach to stdout (handle=1)
  ostream out(&ofb);                 // now attach buffer to stream
  ifb.seekpos(0, ios::in);           // move to top of input buffer
  out << &ifb;                       // stream it to the output

// could replace last statement with the lower level
// gets and puts shown below

// char ch;
// while((ch = ifb.sbumpc()) != EOF)
//   ofb.sputc(ch);

  cout << "\n\n";
}