ncurses help

ncurses help

[Matthew Harrison]

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Hi,
  I am a sorta ok c programmer after becoming a bit of a wizz at perl/php, but
C is a very different language to learn and here I go:

I have been trying to get my first ncurses program working after following all
the examples on www.tldp.org, but now it just either gives me a blank window
(getstr functions still work and the app exits normally) or it just segfaults.

Please can someone glance at the sources (main source is 
inventory-0.1/src/inventory.c in the attached tarball)

TIA

-- 
Mat Harrison
Technical Developer
3d Computer Systems Ltd.
matth@3d-computers.co.uk

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Re: ncurses help

[Matthew Harrison]

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of course it often helps if you attach the file :)

-- 
Mat Harrison
Technical Developer
3d Computer Systems Ltd.
matth@3d-computers.co.uk

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Re: ncurses help

[William N. Zanatta]

  Try changing getstr() to wgetstr(). When doing window manipulation you
must use the functions with support to WINDOW pointers. If you don't,
you'll get the results you're experiencing, because getstr() comes into
action when it is reached while wgetstr() only comes into action after the
wrefresh().

  Also, it showed some problems with placement of the stuff.

  You have set login_window to (login_win.startx, login_win.starty) from
0,0 of the mainscreen. But, when you write stuff into that new window, you
must set the (x,y) from the login_window. iE, here I had:

  login_win.starty -> 7
  login_win.startx -> 25

  thus, after creating the window, (25,7)-terminal turns to
(0,0)-login_window.

  That's it you're working with absolute values when you should work with
relative.

  After all your code turned to...

<inventory.c>
   was
        attron(COLOR_PAIR(1));
        mvwprintw(login_window, ..., ..., "Username: ");
        mvwprintw(login_window, ..., ..., "Password: ");
        attroff(COLOR_PAIR(1));

   changed to

        wattron(login_window, COLOR_PAIR(1));
        mvwprintw(login_window, 1, 1, "Username: ");
        mvwprintw(login_window, 2, 1, "Password: ");
        wattroff(login_window, COLOR_PAIR(1));

   --------

   was
        echo();
        wmove(login_window, ..., ...);
        getstr(username);
        wmove(login_window, ..., ...);
        getstr(password);
        noecho();

   changed to

        echo();
        wmove(login_window, 1, 11);
        wgetstr(login_window,username);
        wmove(login_window, 2, 11);
        wgetstr(login_window,password);
        noecho();

</inventory.c>

  Hope I've helped... =]

  Just a note, you should use wgetnstr() to limit the length of input
data.

  william

Re: ncurses help

[Matthew Harrison]

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thanks William,
	That has solved the problem totally. I know that it seems quite
simple, but I'm finding ncurses quite hard to learn the basics of because
i've never programmed any sort of gui before.

it's taking some hard work.

thanks again, I'm on my way.

On Wed, Sep 10, 2003 at 12:32:11PM -0300, William N. Zanatta wrote:
> 
>   Try changing getstr() to wgetstr(). When doing window manipulation you
> must use the functions with support to WINDOW pointers. If you don't,
> you'll get the results you're experiencing, because getstr() comes into
> action when it is reached while wgetstr() only comes into action after the
> wrefresh().
> 
>   Also, it showed some problems with placement of the stuff.
> 
>   You have set login_window to (login_win.startx, login_win.starty) from
> 0,0 of the mainscreen. But, when you write stuff into that new window, you
> must set the (x,y) from the login_window. iE, here I had:
> 
>   login_win.starty -> 7
>   login_win.startx -> 25
> 
>   thus, after creating the window, (25,7)-terminal turns to
> (0,0)-login_window.
> 
>   That's it you're working with absolute values when you should work with
> relative.
> 
>   After all your code turned to...
> 
> <inventory.c>
>    was
>         attron(COLOR_PAIR(1));
>         mvwprintw(login_window, ..., ..., "Username: ");
>         mvwprintw(login_window, ..., ..., "Password: ");
>         attroff(COLOR_PAIR(1));
> 
>    changed to
> 
>         wattron(login_window, COLOR_PAIR(1));
>         mvwprintw(login_window, 1, 1, "Username: ");
>         mvwprintw(login_window, 2, 1, "Password: ");
>         wattroff(login_window, COLOR_PAIR(1));
> 
>    --------
> 
>    was
>         echo();
>         wmove(login_window, ..., ...);
>         getstr(username);
>         wmove(login_window, ..., ...);
>         getstr(password);
>         noecho();
> 
>    changed to
> 
>         echo();
>         wmove(login_window, 1, 11);
>         wgetstr(login_window,username);
>         wmove(login_window, 2, 11);
>         wgetstr(login_window,password);
>         noecho();
> 
> </inventory.c>
> 
>   Hope I've helped... =]
> 
>   Just a note, you should use wgetnstr() to limit the length of input
> data.
> 
>   william

-- 
Mat Harrison
Technical Developer
3d Computer Systems Ltd.
matth@3d-computers.co.uk

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