NAME¶

std::basic_spanbuf::seekoff - std::basic_spanbuf::seekoff

Synopsis¶

protected:

pos_type seekoff( off_type off, std::ios_base::seekdir dir,
std::ios_base::openmode which = (since C++23)

std::ios_base::in | std::ios_base::out )
override;

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 when there is no
underlying buffer, this function fails if

* 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, or
* dir is std::ios_base::cur and both std::ios_base::in and std::ios_base::out are
set in which, or
* 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, or
* 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 is the pointer to the beginning of the underlying buffer, or the
null pointer value if there is no underlying buffer.

Parameters¶

off - relative position to set the next pointer(s) to
defines base position to apply the relative offset to. It can be one of the
following constants:

dir - Constant Explanation
beg the beginning of a stream
end the ending of a stream
cur the current position of stream position indicator
defines whether the input sequences, the output sequence, or both are
affected. It can be one or a combination of the following constants:
which -
Constant Explanation
in affect the input sequence
out affect the output sequence

Return value¶

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

Example¶

This section is incomplete
Reason: no example

See also¶

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

Category:¶

* Todo no example