31     base::int_type underflow() {return base::underflow();}  in underflow()  function
39         assert(sb.underflow() == '1');  in main()
40         assert(sb.underflow() == '1');  in main()
42         assert(sb.underflow() == '2');  in main()
43         assert(sb.underflow() == '2');  in main()
45         assert(sb.underflow() == '3');  in main()
46         assert(sb.underflow() == '3');  in main()
48         assert(sb.underflow() == EOF);  in main()
49         assert(sb.underflow() == EOF);  in main()
51         assert(sb.underflow() == '4');  in main()
52         assert(sb.underflow() == '4');  in main()