How can I get input without having the user hit [Enter]?

Using standard C/C++, you cannot. However, if you're lucky your compiler may have the non-standard conio.h header (which might include getch()), if you're on *nix (UNIX, Linux, etc.) you can try the ncurses library or switching the terminal mode. On Windows, try the different API input routines (such as those included in the Win32 API).

Got this answer from, password input.