It is used to set position pointer to relative position and sets a new position to the position pointers specified by parameter which. This position is calculated as an offset of off characters relative to a the origin specified by way.
Following is the declaration for std::stringbuf::setbuf.
streampos seekoff (streamoff off, ios_base::seekdir way, ios_base::openmode which = ios_base::in | ios_base::out);
off − It is an offset value.
way − It is an object of type ios_base::seekdir.
It returns the new absolute position the position pointer points to after the call, if representable as a value of type streampos on success or if the above is not possible, the function returns streampos(streamoff(-1)). streampos is a positioning type that can be converted to/from integral types on failure.
Basic guarantee − if an exception is thrown, the object is in a valid state.
it modifies the stringbuf object.