The reason a lot of beginners feel it necessary to put two getch calls in their code is that one single call often doesn’t work.
The reason for that is that getch fetches the next keyboard input from the input queue. Unfortunately, this queue gets filled whenever the user presses keys on the keyboard, even if the application isn’t waiting for input at that moment (of if it isn’t reading the whole input – see Lulu’s answer for an example). As a consequence, getch will fetch a character from the input queue without waiting for the next key press – which is really what the programmer wants.
Of course, this “solution” will still fail in a lot of cases, when there’s more than just one character in the keyboard queue. A better solution is to flush that queue and then request the next character. Unfortunately, there’s no platform-independent way to do this in C/C++ to my knowledge. The conventional way to do this in C++ (sorry, my C is limited) looks like this:
std::cin.ignore(std::cin.rdbuf()->in_avail());
This simply ignores all available input, effectively clearing the input queue. Unfortunately, this code doesn’t always work, either (for very arcane reasons).
