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std::basic_filebuf::seekpos

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< cpp‎ | io‎ | basic filebuf
Revision as of 08:21, 15 August 2013 by P12 (Talk | contribs)

protected:

virtual pos_type seekpos( pos_type sp,

                          std::ios_base::openmode which = std::ios_base::in | std::ios_base::out );

Repositions the file pointer, if possible, to the position indicated by sp.

If the associated file is not open (is_open()==false), fails immediately.

If the file is open for writing, first writes the put area and any unshift sequences required by the currently imbued locale, using overflow()

Then repositions the file pointer, as by calling std::fseek()

If the file is open for reading, updates the get area if necessary.

If sp was not obtained by calling seekoff() or seekpos() on the same file, the behavior is undefined.

Contents

Parameters

sp - file position obtained by seekoff() or seekpos() called earlier on the same file
which - defines which of the input and/or output sequences to affect. It can be one or a combination of the following constants:
Constant Explanation
in affect the input sequence
out affect the output sequence

Return value

sp on success or pos_type(off_type(-1)) on failure.

Notes

seekpos() is called by std::basic_streambuf::pubseekpos(), which is called by the single-argument versions of std::basic_istream::seekg() and std::basic_ostream::seekp()

Example

See also

invokes seekpos()
(public member function of std::basic_streambuf) [edit]
[virtual]
repositions the file position, using relative addressing
(virtual protected member function) [edit]
moves the file position indicator to a specific location in a file
(function) [edit]