Isolating stdin and stdout within a terminal

Question

I'm developing a CLI program, in C, for my systems class project, and it needs to display incoming text while maintaining a command prompt. Left alone, the incoming text will saw through whatever one tries to type. In other applications I've seen the incoming text print above(or below) the prompt itself. Is there any way to implement this in ANSI escapes? ncurses seems like overkill.

Answer 1

You can print \r to erase the prompt: It will return the cursor to the beginning of the current line. You can then print your output followed by some spaces to clear out any remaining input characters, newline, and reprint the prompt.

With ANSI sequences or terminal-specific libraries you can do even more, but this I think is all you can do reliably using only ASCII. Apart from printing 242 blank lines to redraw the whole screen, of course.

Edit: Sorry, I didn't answer the ANSI part properly. With cursor movement control codes and printing space over existing characters, you can pretty much do anything, and there are some convenience actions to help you, such as "delete line". But keep in mind that Windows doesn't play nice w/ ANSI post XP, and neither are other systems guaranteed to.

Answer 2

For one thing, if you want to maintain a prompt, while printing, you can not use things like scanf. You have to intercept keyboard events or use a non waiting method to get input. Then you can get the terminal number of lines (n) and print the last n-1 lines of your output, and then a prompt.

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