Screen Handling

[Curious Student]

I was looking at methods of clearing the screen. I remember using
clrscr() in C on a Unix machine when I was at the institute learning
software development. I tried using it on MS VC++ 6.0. It didn't work.
I looked up the documentation. The documentation said this is a
non-standard function and is included in conio.h. I had included
conio.h already, and yet it couldn't link. I guess clrscr is a unix
thing then?

I also found this code in a book as well as on the Net about clearing
the screen:

THIS CAME FROM A DOWNLOADED SAMPLE
printf("\033[2J"); /* Clear the entire screen. */
printf("\033[0;0f"); /* Move cursor to the top left hand corner */



THIS CAME FROM A BOOK
printf("\x1B[2J");


I also found some documentation saying there was this library called
curses that was very interesting and it dealt with screen handling
functions. I looked it up on Google and found the documentation for
the header curses.h and an overview. But I think I'll also need the
DLL along with the header, so I can use the curses.

My questions are:

(1) Why is it that the phrase "\x1B[2J" should cause the screen to
clear?

(2) Why doesn't it work for me?

(3) Where can I get the necessary files to use curses? Where can I get
some tutorial on using curses, because I saw there was no function to
create a window/console, but there were functions for manipulating
windows (example colorwindow etc.) and they all expected a WINDOW data
type (that's no problem, that's declared in the header, but how do I
fetch a window's. Should I just use the Win32 API GetWindow etc?
Surely, it wouldn't be a Win32 platform specific library - this
curses?).

[Thomas Matthews]

Re: Screen Handling

Curious Student wrote:[color=blue]
> I was looking at methods of clearing the screen. I remember using
> clrscr() in C on a Unix machine when I was at the institute learning
> software development. I tried using it on MS VC++ 6.0. It didn't work.
> I looked up the documentation. The documentation said this is a
> non-standard function and is included in conio.h. I had included
> conio.h already, and yet it couldn't link. I guess clrscr is a unix
> thing then?
>
> I also found this code in a book as well as on the Net about clearing
> the screen:
>
> THIS CAME FROM A DOWNLOADED SAMPLE
> printf("\033[2J"); /* Clear the entire screen. */
> printf("\033[0;0f"); /* Move cursor to the top left hand corner */
>
>
>
> THIS CAME FROM A BOOK
> printf("\x1B[2J");
>
>
> I also found some documentation saying there was this library called
> curses that was very interesting and it dealt with screen handling
> functions. I looked it up on Google and found the documentation for
> the header curses.h and an overview. But I think I'll also need the
> DLL along with the header, so I can use the curses.[/color]
Congradulations , you have found out why clearing the screen is not
part of the standard language (and thus not discussed in this
newsgroup). However, it _is_ a FAQ:

http://www.eskimo.com/~scs/c-faq/q19.4.html

[color=blue]
>
> My questions are:
>
> (1) Why is it that the phrase "\x1B[2J" should cause the screen to
> clear?[/color]
Because that is a command for a terminal that supports the
ANSI terminal escape sequences. Different terminals have different
commands to clear the screen. This is what the "curses" library
is based on.

[color=blue]
>
> (2) Why doesn't it work for me?[/color]
You are probably working with a terminal / window that doesn't
support the ANSI escape sequences.

[color=blue]
>
> (3) Where can I get the necessary files to use curses?[/color]

http://www.google.com

http://www.fsf.org

http://www.sourceforge.org

[color=blue]
> Where can I get some tutorial on using curses, because I saw
> there was no function to
> create a window/console, but there were functions for manipulating
> windows (example colorwindow etc.) and they all expected a WINDOW data
> type (that's no problem, that's declared in the header, but how do I
> fetch a window's. Should I just use the Win32 API GetWindow etc?
> Surely, it wouldn't be a Win32 platform specific library - this
> curses?).[/color]
http://www.google.com, use "curses tutorial".
Perhaps a good book about the Unix operating system.


--
Thomas Matthews

C++ newsgroup welcome message:

http://www.slack.net/~shiva/welcome.txt

C++ Faq: http://www.parashift.com/c++-faq-lite
C Faq: http://www.eskimo.com/~scs/c-faq/top.html
alt.comp.lang.l earn.c-c++ faq:

http://www.comeaucomputing.com/learn/faq/

Other sites:
http://www.josuttis.com -- C++ STL Library book

[Dan Pop]

Re: Screen Handling

In <c520b56a.04092 20227.1dab5662@ posting.google. com> estudiantin@red iffmail.com (Curious Student) writes:
[color=blue]
>I was looking at methods of clearing the screen.[/color]

And you have missed the first reference document you have to read *before*
posting here: the comp.lang.c FAQ.

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Dan.Pop@ifh.de
Currently looking for a job in the European Union

[Malcolm]

Re: Screen Handling

"Curious Student" <estudiantin@re diffmail.com> wrote[color=blue]
>
> I was looking at methods of clearing the screen. I remember using
> clrscr() in C on a Unix machine when I was at the institute learning
> software development.
>[/color]
Unfortunately there are no ANSI C functions for manipulating the display.
You receive characters from stdin, and send characters to stdout. If you
want to clear the screen, print green text, suppress echoing to input a
password, you must use a platform-specific library.

[Keith Thompson]

Re: Screen Handling

"Malcolm" <malcolm@55bank .freeserve.co.u k> writes:[color=blue]
> "Curious Student" <estudiantin@re diffmail.com> wrote[color=green]
>> I was looking at methods of clearing the screen. I remember using
>> clrscr() in C on a Unix machine when I was at the institute learning
>> software development.
>>[/color]
> Unfortunately there are no ANSI C functions for manipulating the display.
> You receive characters from stdin, and send characters to stdout. If you
> want to clear the screen, print green text, suppress echoing to input a
> password, you must use a platform-specific library.[/color]

<QUIBBLE>

You must write platform-specific code. It may not be necessary to
use a platform-specific library (though that's usually the best
way to do it). For example, the following program:

#include <stdio.h>
int main(void)
{
fputs("\033[1;1H\033[2J", stdout);
return 0;
}

*might* clear the screen on your system (it does on mine); if so, it
does so without using any platform-specific library.

The advantage of using a platform-specific library, of course, is that
you don't have to reinvent the wheel.

</QUIBBLE>

--
Keith Thompson (The_Other_Keit h) kst-u@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.