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

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std::basic_spanbuf

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basic_spanbuf::basic_spanbuf (C++23)
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Protected member functions
basic_spanbuf::setbuf (C++23)
basic_spanbuf::seekoff (C++23)
basic_spanbuf::seekpos (C++23)
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swap(std::basic_spanbuf) (C++23)

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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 exactlyoff characters from beginning, end, or current position of the get and/or put area of the buffer.

Letn be the number ofCharT elements in underlying buffer, or0 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 computednewoff (see below) is not zero, which may occur if there is no underlying buffer, or the*this is not opened in the mode required bywhich, or
dir isstd::ios_base::cur and bothstd::ios_base::in andstd::ios_base::out are set inwhich, or
the computednewoff is not representable inoff_type, less than zero, or greater thann.

newoff is computed as below:

Ifdir isstd::ios_base::beg,newoff isoff.
Ifdir isstd::ios_base::cur,newoff is
- pptr()- pbase()+ off ifstd::ios_base::out is set inwhich, or
- gptr()- eback()+ off ifstd::ios_base::in is set inwhich.
Ifdir isstd::ios_base::end,newoff is
- pptr()- pbase()+ off ifstd::ios_base::out but notstd::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 topbuf+ newoff on success ifstd::ios_base::in and/orstd::ios_base::out is correspondingly set inwhich, wherepbuf is the pointer to the beginning of the underlying buffer, or the null pointer value if there is no underlying buffer.

[edit]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

[edit]Return value

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

[edit]Example

This section is incomplete
Reason: no example

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