Question

I want to write a C program that tokenizes a string and prints it out word by word, slowly, and I want it to simultaneously listen for the user pressing Enter, at which point they will be able to input data. Is this possible?

Answer 1

Update: see @modifiable-lvalue ‘s comment below for additional helpful information, e.g., using getchar() instead of getch(), if you go that route.

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Definitely possible. Just be aware that gets() may not be entirely helpful for this purpose, since gets() interprets enter not as enter per se, but as “now, I the user, have entered as much string as I want to”. So the input gathered by gets() from pressing just an enter will appear as an empty string (which might be workable for you).
See: http://www.cplusplus.com/reference/cstdio/gets/.
But there are other reasons not to use gets()–it does not let you specify a maximum to read in, so it’s easy to overflow whatever buffer you are using. A security and bug nightmare waiting to happen. So you want fgets(), which allows you to specify a maximum size to read in. fgets() will place a newline in the string when an enter is pressed. (BTW, props to @jazzbassrob on fgets()).

You could also consider something like getch()–which really deals with individual key-presses (but it gets a bit complicated handling keys that have non-straightforward scan-codes). You may find this example helpful: http://www.daniweb.com/software-development/cpp/code/216732/reading-scan-codes-from-the-keyboard. But because of the scancodes issues, getch() is subject to platform details.

So if you want a more portable approach, you may need to use something heavier weight, but fairly portable, such as ncurses.

I suspect you can do what you want with either fgets(), keeping in mind that enter will give you a string with just a newline in it, or getch().

I just wanted you to be aware of some of the implementation/platform issues that can arise.

C can absolutely do this, but it’s a little more complicated than one might guess at first attempt. That’s because terminal input is, historically, very platform dependent.