clear_screen
xputs(clear_screen);
if (clear_screen == NULL)
if (!clear_screen) {
tputs(clear_screen, 0, ttputch);
if (clear_screen == NULL)
putpad(clear_screen);
tputs(clear_screen, 0, __cputchar);
if (clear_screen)
putpad(clear_screen);
if (clear_screen)
tputs(clear_screen, 1, putchar);