Control key with Ncurses

Control key with Ncurses

[Vidya Kotamraju]

Hi all,

I am writing a graphics-based application in Linux by making use of C 
and ncurses library.
The application needs that i take two numbers as input ( i make use of 
scanw for the same).
However at this point in the program i want the user to obtain the 
flexibility of exiting gracefully from the program(by pressing a cntrl 
key,like say F5).

Cntrl-D doesnt seem to work with ncurses..

Heres a snippet of the code.....



/*FORM INITIALIZATION*/

my_form = new_form(field);
post_form(my_form);
refresh();

mvprintw(1,8,"NOTE:THE ROW AND COLUMN ARE AS DEFINED IN MATRIXALGEBRA");
mvprintw(2,8,"Enter the row and column coordinates(i and j values):");

mvprintw(3,8,"i and j: ");
scanw("%d %d",&i,&j);

// at this point i want to exit from the program if F5 key is pressed.



Any pointers ?

Regards,
Vidya

-- 
--------------------------------------------------------------------------
As far as the laws of mathematics refer to reality,they are not certain;
and as far as they are certain, they do not refer to reality.
                                       - Albert Einstein (1879-1955)
--------------------------------------------------------------------------
Kotamraju Vidya
Marine HydroDynamics Lab,
Physical Oceanography Division,
National Institute of Oceanography,
Dona Paula, Goa 403 004, India.
Ph.: +91-832-2456700 *4400 (O)
      +91-832-2541756 (R)
e-mail: vidyakr@darya.nio.org

Re: Control key with Ncurses

[Glynn Clements]

Vidya Kotamraju wrote:

> I am writing a graphics-based application in Linux by making use of C 
> and ncurses library.
> The application needs that i take two numbers as input ( i make use of 
> scanw for the same).
> However at this point in the program i want the user to obtain the 
> flexibility of exiting gracefully from the program(by pressing a cntrl 
> key,like say F5).

You need to call keypad() to enable the use of "extended" keys
(funcion keys, arrow keys etc). The various KEY_* macros define the
codes for the extended keys; for function keys, use KEY_F(), e.g. 
KEY_F(5) for F5.

> Cntrl-D doesnt seem to work with ncurses..

Control codes should be reported by getch() etc as a code in the range
0 to 31 (e.g. Ctrl-D should be code 4).

-- 
Glynn Clements <glynn.clements@virgin.net>

Re: Control key with Ncurses

[Vidya Kotamraju]

I had enabled the keypad() along with the other graphics initializations.
Also, Control codes do work with getch().
But what i need to know is how to make use of a control key to exit out 
of a scanw input. (As control-D would work with scanf without needing to 
make use of getchar)


Regards,
Vidya.

Glynn Clements wrote:

 > Vidya Kotamraju wrote:
 >
 >
 >>I am writing a graphics-based application in Linux by making use of C
 >>and ncurses library.
 >>The application needs that i take two numbers as input ( i make use of
 >>scanw for the same).
 >>However at this point in the program i want the user to obtain the
 >>flexibility of exiting gracefully from the program(by pressing a cntrl
 >>key,like say F5).
 >>
 >
 > You need to call keypad() to enable the use of "extended" keys
 > (funcion keys, arrow keys etc). The various KEY_* macros define the
 > codes for the extended keys; for function keys, use KEY_F(), e.g.
 > KEY_F(5) for F5.
 >
 >
 >>Cntrl-D doesnt seem to work with ncurses..
 >>
 >
 > Control codes should be reported by getch() etc as a code in the range
 > 0 to 31 (e.g. Ctrl-D should be code 4).
 >
 >


-- 
--------------------------------------------------------------------------
As far as the laws of mathematics refer to reality,they are not certain;
and as far as they are certain, they do not refer to reality.
                                        - Albert Einstein (1879-1955)
--------------------------------------------------------------------------
Kotamraju Vidya
Marine HydroDynamics Lab,
Physical Oceanography Division,
National Institute of Oceanography,
Dona Paula, Goa 403 004, India.
Ph.: +91-832-2456700 *4400 (O)
       +91-832-2541756 (R)
e-mail: vidyakr@darya.nio.org

Re: Control key with Ncurses

[Glynn Clements]

Vidya Kotamraju wrote:

> I had enabled the keypad() along with the other graphics initializations.
> Also, Control codes do work with getch().
> But what i need to know is how to make use of a control key to exit out 
> of a scanw input. (As control-D would work with scanf without needing to 
> make use of getchar)

You can't; getstr() (which scanw() uses) won't return until you press
Return/Enter. If you want to be able to interrupt it, you would have
to read the string manually using repeated calls to getch(), then use
sscanf() to parse it.

-- 
Glynn Clements <glynn.clements@virgin.net>