std::basic_spanbuf<CharT,Traits>::seekoff

protected : pos_type seekoff( off_type off, std::ios_base::seekdir dir, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out ) override;		(since C++23)

Repositions the next pointer to get and/or put area, if possible, to the position that corresponds to exactly off characters from beginning, end, or current position of the get and/or put area of the buffer.

Let n be the number of CharT elements in underlying buffer, or ​0​

• the next pointer to the get and/or put area to reposition is null and the computed newoff (see below) is not zero, which may occur if there is no underlying buffer, or the *this is not opened in the mode required by which
• dir is std::ios_base::cur and both std::ios_base::in and std::ios_base::out are set in which
• the computed newoff is not representable in off_type, less than zero, or greater than n.

newoff is computed as below:

• If dir is std::ios_base::beg, newoff is off.
• If dir is std::ios_base::cur, newoff is
  • pptr() - pbase() + off if std::ios_base::out is set in which
  • gptr() - eback() + off if std::ios_base::in is set in which
• If dir is std::ios_base::end, newoff is
  • pptr() - pbase() + off if std::ios_base::out but not std::ios_base::in is set in the open mode of *this
  • otherwise, off + n.

This function repositions the next pointer to get and/or put area to pbuf + newoff on success if std::ios_base::in and/or std::ios_base::out is correspondingly set in which, where pbuf

Parameters

off	-	relative position to set the next pointer(s) to
dir	-	defines base position to apply the relative offset to. It can be one of the following constants: Constant Explanation beg the beginning of a stream end the ending of a stream cur the current position of stream position indicator
which	-	defines whether the input sequences, the output sequence, or both are affected. 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

pos_type(newoff) on success, pos_type(off_type(-1))

Example

This section is incomplete Reason: no example

See also

seekoff [virtual]	repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function of std::basic_stringbuf<CharT,Traits,Allocator>)
seekoff [virtual]	repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function of std::strstreambuf)