Effects:
Constructs an object of class
strstream,
initializing the base class with
iostream(&sb)
and initializing
sb with one of the two constructors:
If
(mode & app) == 0,
then
s shall designate the first element of an array of
n elements
. The constructor is
strstreambuf(s,n,s).If
(mode & app) != 0,
then
s shall
designate the first element of an array of
n elements that contains
an
ntbs whose first element is designated by
s. The constructor is
strstreambuf(s,n,s + std::strlen(s)).