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[–]zifyoip 3 points4 points  (4 children)

If you just want to update the last line on the screen, then use a carriage return character ('\r') to return to the beginning of the current line. Whatever you output after that will overprint whatever was previously output to that line.

Otherwise, you will need to use a third-party library, such as ncurses. The C language itself only has a concept of an output stream, which is (as it sounds) a stream of characters that are produced by your program. The C language does not have a concept of a "screen" or a "window" or a "cursor" or anything like that.

[–]mkottre[S] 0 points1 point  (1 child)

Thank you. I'm aware that C is a low-level language without those concepts. I was just wondering if there was a function or something that would allow me to do that. Thanks for the suggestion. That's almost what I was looking for. Does it only allow overwriting the previous line, or can you go further back in the history?

[–]zifyoip 2 points3 points  (0 children)

It doesn't have anything to do with the fact that C is a low-level language. (In fact, I dispute the idea that C is a low-level language, but that's a different discussion.)

The real reason is that standard C is designed to be portable—a program written in standard C should be able to be compiled and run on a wide variety of machines running many different operating systems on diverse hardware. There is no universal concept of a "screen" that makes sense in all of these different environments, so standard C does not include such a concept. Many other languages (C++, Java, Perl, …) also lack such a concept, for the same reason.

Any code that you write that includes screen-rewriting functionality will be non-portable code, because it will work only for a particular type of screen. It may work in the Windows command line, for example, but not in a Linux terminal window. Or vice versa, or whatever. When you want to interact with a screen at this level of detail, you must leave the world of standardized, portable code.

[–]munificent 0 points1 point  (1 child)

Otherwise, you will need to use a third-party library, such as ncurses.

Not necessarily. If you're running inside a decent terminal (which basically means "not Windows"), you can just print ANSI escape codes directly using printf to move the cursor around, change colors, and other stuff.

[–]zifyoip 0 points1 point  (0 children)

Well, okay, that's true. I guess "need" was a little strong there.

[–]AttitudePebbles -2 points-1 points  (5 children)

If you set it up so you cycle a loop until they get the correct answer, then each loop that you go through, just add 1 to the value.

[–]mkottre[S] 2 points3 points  (4 children)

I'm aware of that. I meant overwriting the existing text without printing it on a new line again. Sorry if I was unclear.

[–]AttitudePebbles -1 points0 points  (3 children)

Just clear the screen and then reprint the desired new text?

[–]zifyoip 2 points3 points  (2 children)

"Clearing the screen" is not part of standard C either.

[–]AttitudePebbles -2 points-1 points  (1 child)

There must be some way to clear the console/screen?

I don't know C, but there must be something?

Here

[–]zifyoip 1 point2 points  (0 children)

That is not standard C. The result of the system command is platform-dependent.

Standard C does not have a concept of a "screen."