streampos pubseekoff ( streamoff off, ios_base::seekdir way, ios_base::openmode which = ios_base::in | ios_base::out );

Set internal position pointer to relative position

Calls protected virtual member seekoff, which sets a new position value for one or both of the internal position pointers.

The parameter which determines which of the position pointers is affected: either the get pointer gptr or the put pointer pptr, or both.

Parameters

off

Offset value. This is relative to the way parameter.
It is a value of type streamoff, which can be implicitly constructed from an integral value.

way

Object of type ios_base::seekdir. It may take any of the following constant values:

value	offset is relative to...
ios_base::beg	beginning of the stream buffer
ios_base::cur	current position in the stream buffer
ios_base::end	end of the stream buffer

which

Determines which of the internal position pointers shall be modified: the input pointer, the output pointer, or both. It is an object of type ios_base::openmode that for this function may take any combination of the following significant constant values:

value	position pointer affected
ios_base::in	Modify get pointer position
ios_base::out	Modify put pointer position

Return Value

Example

// get file size using pubseekoff
#include <iostream>
#include <fstream>
using namespace std;

int main () {

  long size;
  filebuf* pbuf;

  fstream filestr ("test.txt");
  pbuf = filestr.rdbuf();
  size = pbuf->pubseekoff(0,ios_base::end);
  filestr.close();

  cout << "size of file is " << size << endl;

  return 0;
}

This program prints out the size of file test.txt using the value returned by pubseekoff when it repositions the position pointer to the end of the file buffer.

Basic template member declaration

typedef traits::pos_type pos_type;
typedef traits::off_type off_type;
pos_type pubseekoff (off_type off, ios_base::seekdir way, ios_base which = ios_base::in | ios_base::out );

See also