filebuf object Vc++

[sangeetha jagannathan]

hi
can anyone explain me this code, instruction by instruction. i am not able to follow it.

#include <iostream.h>
#include <fstream.h>
#include <stdio.h>
#include "logger.h"
#include "dostuff.h"
 
class MyOStream : public ostream {
  public:
    MyOStream() : ostream() {
      filebuf * buf = new filebuf();
      int i = 0;
      char buffer[256] = "log000000.txt";
      while (!buf->open(buffer, ios::out | ios::noreplace)) {
        sprintf(buffer, "log%06d.txt", ++i);
      }
 
      ios::init(buf);
      ios::delbuf(1);
    }
};
 
int main(int, char **) {
  MyOStream os;
  if (os.good()) {
    Logger log(os);
    do_stuff(log);
  }
 
  return 0;
}

[sicarie]

hi
can anyone explain me this code, instruction by instruction. i am not able to follow it.

#include <iostream.h>
#include <fstream.h>
#include <stdio.h>
#include "logger.h"
#include "dostuff.h"
 
class MyOStream : public ostream {
  public:
    MyOStream() : ostream() {
      filebuf * buf = new filebuf();
      int i = 0;
      char buffer[256] = "log000000.txt";
      while (!buf->open(buffer, ios::out | ios::noreplace)) {
        sprintf(buffer, "log%06d.txt", ++i);
      }
 
      ios::init(buf);
      ios::delbuf(1);
    }
};
 
int main(int, char **) {
  MyOStream os;
  if (os.good()) {
    Logger log(os);
    do_stuff(log);
  }
 
  return 0;
}

What parts do you not understand? When you start reading it, where do you get stuck?

[sangeetha jagannathan]

What parts do you not understand? When you start reading it, where do you get stuck?

i get stuck here

filebuf * buf = new filebuf();
int i = 0;
char buffer[256] = "log000000.txt";
while (!buf->open(buffer, ios::out | ios::noreplace)) {
sprintf(buffer, "log%06d.txt", ++i);
}

[enri]

i get stuck here

filebuf * buf = new filebuf();
int i = 0;
char buffer[256] = "log000000.txt";
while (!buf->open(buffer, ios::out | ios::noreplace)) {
sprintf(buffer, "log%06d.txt", ++i);
}

The first line creates a new object filebuf by mean of its constructor "filebuf()", and address it using a pointer to filebuf called "buf".
Then a file name "log000000.txt" is initialized.
The cyvle, checks if a file named "log000000.txt" exist, using the filebuf method open(). If it exist, it changes the file name to "log000001.txt", and checks it existence, and son on incrementing the file number to log000002.txt, log000003.txt and so on