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form(3) Library calls form(3)

form - curses extension for programming forms

#include <form.h>

The form library provides terminal-independent facilities for composing form screens on character-cell terminals. The library includes: field routines, which create and modify form fields; and form routines, which group fields into forms, display forms on the screen, and handle interaction with the user.

The form library uses the curses libraries. To use the form library, link with the options -lform -lcurses.

Your program should set up the locale, e.g.,


setlocale(LC_ALL, "");

so that input/output processing will work.

A curses initialization routine such as initscr must be called before using any of these functions.

The form library maintains a default value for field attributes. You can get or set this default by calling the appropriate set_ or retrieval routine with a NULL field pointer. Changing this default with a set_ function affects future field creations, but does not change the rendering of fields already created.

The following table lists each form routine and the name of the manual page on which it is described. Routines flagged with “*” are ncurses-specific, not present in SVr4.

curses Routine Name Manual Page Name
current_field form_page(3)
data_ahead form_data(3)
data_behind form_data(3)
dup_field form_field_new(3)
dynamic_field_info form_field_info(3)
field_arg form_field_validation(3)
field_back form_field_attributes(3)
field_buffer form_field_buffer(3)
field_count form_field(3)
field_fore form_field_attributes(3)
field_index form_page(3)
field_info form_field_info(3)
field_init form_hook(3)
field_just form_field_just(3)
field_opts form_field_opts(3)
field_opts_off form_field_opts(3)
field_opts_on form_field_opts(3)
field_pad form_field_attributes(3)
field_status form_field_buffer(3)
field_term form_hook(3)
field_type form_field_validation(3)
field_userptr form_field_userptr(3)
form_driver form_driver(3)
form_driver_w form_driver(3)*
form_fields form_field(3)
form_init form_hook(3)
form_opts form_opts(3)
form_opts_off form_opts(3)
form_opts_on form_opts(3)
form_page form_page(3)
form_request_by_name form_requestname(3)*
form_request_name form_requestname(3)*
form_sub form_win(3)
form_term form_hook(3)
form_userptr form_userptr(3)
form_win form_win(3)
free_field form_field_new(3)
free_fieldtype form_fieldtype(3)
free_form form_new(3)
link_field form_field_new(3)
link_fieldtype form_fieldtype(3)
move_field form_field(3)
new_field form_field_new(3)
new_fieldtype form_fieldtype(3)
new_form form_new(3)
new_page form_new_page(3)
pos_form_cursor form_cursor(3)
post_form form_post(3)
scale_form form_win(3)
set_current_field form_page(3)
set_field_back form_field_attributes(3)
set_field_buffer form_field_buffer(3)
set_field_fore form_field_attributes(3)
set_field_init form_hook(3)
set_field_just form_field_just(3)
set_field_opts form_field_opts(3)
set_field_pad form_field_attributes(3)
set_field_status form_field_buffer(3)
set_field_term form_hook(3)
set_field_type form_field_validation(3)
set_field_userptr form_field_userptr(3)
set_fieldtype_arg form_fieldtype(3)
set_fieldtype_choice form_fieldtype(3)
set_form_fields form_field(3)
set_form_init form_hook(3)
set_form_opts form_field_opts(3)
set_form_page form_page(3)
set_form_sub form_win(3)
set_form_term form_hook(3)
set_form_userptr form_userptr(3)
set_form_win form_win(3)
set_max_field form_field_buffer(3)
set_new_page form_new_page(3)
unfocus_current_field form_page(3)*
unpost_form form_post(3)

Routines that return pointers return NULL on error, and set errno to the corresponding error-code returned by functions returning an integer. Routines that return an integer return one of the following error codes:

The routine succeeded.
Routine detected an incorrect or out-of-range argument.
Routine was called from an initialization or termination function.
The field is already connected to a form.
Contents of a field are not valid.
No fields are connected to the form.
The form has not been posted.
Form is too large for its window.
The form is already posted.
The form driver could not process the request.
System error occurred (see errno(3)).
The form driver code saw an unknown request code.

The header file <form.h> automatically includes the header files <curses.h> and <eti.h>.

In your library list, libform.a should be before libncurses.a; that is, you want to say “-lform -lncurses”, not the other way around (which would give you a link error when using static libraries).

These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions.

The menu facility was documented in SVr4.2 in Character User Interface Programming (UNIX SVR4.2).

It is not part of X/Open Curses.

Aside from ncurses, there are few implementations:

A few functions in this implementation are extensions added for ncurses, but not provided by other implementations, e.g., form_driver_w, unfocus_current_field.

Juergen Pfeifer. Manual pages and adaptation for ncurses by Eric S. Raymond.

curses(3) and related pages whose names begin “form_” for detailed descriptions of the entry points.

This describes ncurses version 6.4 (patch 20230826).

2023-08-19 ncurses 6.4