libio
Since the iostream classes are so fundamental to standard C++,
the Free Software Foundation has agreed to a special exception to its
standard license, when you link programs with libio.a:
As a special exception, if you link this library with files compiled with a GNU compiler to produce an executable, this does not cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License.
The code is under the GNU General Public License (version 2) for all other purposes than linking with this library; that means that you can modify and redistribute the code as usual, but remember that if you do, your modifications, and anything you link with the modified code, must be available to others on the same terms.
These functions are also available as part of the libg++
library; if you link with that library instead of libio, the
GNU Library General Public License applies.