Date: Thu, 28 Aug 2008 06:42:31 +0200 From: Polytropon <freebsd@edvax.de> To: Christopher Joyner <chris27wjoyner@gmail.com> Cc: Christopher Joyner <chris27wjoyner@yahoo.com>, questions@freebsd.org Subject: Re: curses.h, beep() returns ERR, flash() casuses segment fault. Message-ID: <20080828064231.110a9e80.freebsd@edvax.de> In-Reply-To: <898452.32176.qm@web56714.mail.re3.yahoo.com> References: <898452.32176.qm@web56714.mail.re3.yahoo.com>
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Good morning!
On Wed, 27 Aug 2008 19:10:40 -0700 (PDT), Christopher Joyner <chris27wjoyner@yahoo.com> wrote:
> I do not get the OK from beep, and flash crashes the program.
> This is my code:
>
> #include <curses.h>
>
> int main(int argc,char** argv)
> {
> if(beep()!=OK)
> printf("No OK\n"); fflush(stdout);
> if(flash()!=OK)
> printf("No Flash\n"); fflush(stdout);
> return 0;
> }
First of all, fflush seems to need a definition from stdio.h.
I'm not sure if it's included by default (such as -lc is).
I tried to link with -lcurses and -lncurses and I can reproduce
the error you mentioned:
/* beepflash.c */
#include <stdio.h>
#include <curses.h>
int main(int argc, char **argv)
{
printf("beep: %d\n", beep());
fflush(stdout);
printf("flash: %d\n", flash());
fflush(stdout);
return 0;
}
% cc -Wall -lncurses -o beepflash beepflash.c
% ./beepflash
-1
Segmentation fault (core dumped)
Allthough I did a lot of programming with NCurses, I'm not sure
where this error comes from. My old programs do work with the
ncurses installation I have (compile + run), but none of them
uses flash() or beep(). I found out that no ncurses package is
installed.
So I did
# pkg_add -r ncurses
to install devel/ncurses (ncurses-5.6_2) and repeated the compile
process - same result. So I went to check the main difference
between my working programs and your code, because I noticed that
if I put a beep() and a flash() call into my program, they worked
as expected.
Solution: Prior to any call to the ncurses library, put these
into your code:
initscr();
cbreak();
noecho();
nonl();
intrflush(stdscr, FALSE);
keypad(stdscr, TRUE);
start_color();
I'm not sure which are essential to make beep() and flash() work
as expected, but you can easily find out which ones you don't need.
Explaination: The ncurses library / seesion doesn't seem to be
initialized correctly, that's why beep() didn't work and flash()
caused a segmentation fault.
--
Polytropon
>From Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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