std::basic_stringbuf<CharT,Traits,Allocator>::seekpos
Min standard notice:
Repositions std::basic_streambuf::gptr and/or std::basic_streambuf::pptr, if possible, to the position indicated by sp.
# Declarations
protected:
virtual pos_type seekpos( pos_type sp,
std::ios_base::openmode which = std::ios_base::in | std::ios_base::out );
# Parameters
sp: stream position, such as one obtained by seekoff() or seekpos()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
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
#include <sstream>
#include <iostream>
struct mybuf : std::stringbuf
{
mybuf(const std::string& str) : std::stringbuf(str) {}
pos_type seekpos(pos_type sp, std::ios_base::openmode which)
{
std::cout << "Before seekpos(" << sp << "), size of the get area is "
<< egptr() - eback() << " with "
<< egptr() - gptr() << " read positions available.\n";
pos_type rc = std::stringbuf::seekpos(sp, which);
std::cout << "seekpos() returns " << rc << ".\nAfter the call, "
<< "size of the get area is "
<< egptr() - eback() << " with "
<< egptr() - gptr() << " read positions available.\n";
return rc;
}
};
int main()
{
mybuf buf("12345");
std::iostream stream(&buf);
stream.seekg(2);
}
# Defect reports
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 375 | C++98 | static constant members of std::ios_base weremisspecified as members of std::basic_ios | corrected |
| LWG 564 | C++98 | if was unclear how to reposition gptr and/or pptr | they are repositioned by seekoff() |