The class
basic_stringbuf
is derived from
basic_streambuf
to associate possibly the input sequence and possibly
the output sequence with a sequence of arbitrary
characters.
The sequence can be initialized from, or made available as, an object of class
basic_string.
init_buf_ptrs() sets the base class'
get area ([streambuf.get.area]) and
put area ([streambuf.put.area]) pointers
after initializing, moving from, or assigning to buf accordingly.