Any implementation of curses must not free the memory associated with a screen, since (even after calling endwin), it must be available for use in the next call to refresh(3X). There are also chunks of memory held for performance reasons. That makes it hard to analyze curses applications for memory leaks. When using the specially configured debugging version of the ncurses library, applications can call functions which free those chunks of memory, simplifying the process of memory-leak checking.
Some of the functions are named with a ``_nc_'' prefix because they are not intended for use in the non-debugging library:
The functions prefixed ``_nc'' are normally not available; they must be configured into the library at build time using the --disable-leaks option. That compiles-in code that frees memory that normally would not be freed.
The exit_curses and exit_terminfo functions call _nc_free_and_exit and _nc_free_tinfo if the library is configured to support memory-leak checking. If the library is not configured to support memory-leak checking, they simply call exit.