# form_field_buffer 3x 2024-12-28 ncurses 6.6 Library calls

    form_field_buffer(3x)            Library calls           form_field_buffer(3x)

## NAME

           form_field_buffer - field buffer control

## SYNOPSIS

           #include <form.h>

           int set_field_buffer(FIELD *field, int buf, const char *value);
           char *field_buffer(const FIELD *field, int buffer);

           int set_field_status(FIELD *field, bool status);
           bool field_status(const FIELD *field);

           int set_max_field(FIELD *field, int max);

## DESCRIPTION

           The  function  set_field_buffer  sets  the numbered buffer of the given
           field to contain a given string:

              o   Buffer 0 is the displayed value of the field.

              o   Other numbered buffers may be allocated by applications  through
                  the  nbuf  argument  of  (see  form_field_new(3x))  but  are not
                  manipulated by the forms library.

           The function field_buffer returns a pointer  to  the  contents  of  the
           given numbered buffer:

              o   The  buffer contents always have the same length, and are padded
                  with trailing spaces as needed to  ensure  this  length  is  the
                  same.

              o   The  buffer  may contain leading spaces, depending on how it was
                  set.

              o   The buffer contents are set with set_field_buffer, or as a  side
                  effect of any editing operations on the corresponding field.

              o   Editing  operations  are  based on the window which displays the
                  field, rather than a string.  The window contains only printable
                  characters, and is filled with blanks.   If  you  want  the  raw
                  data,  you must write your own routine that copies the value out
                  of the buffer and removes the leading and trailing spaces.

              o   Because editing operations change the content of the  buffer  to
                  correspond  to  the window, you should not rely on using buffers
                  for long-term storage of form data.

           The function set_field_status sets the associated status flag of field;
           field_status gets the current value.  The  status  flag  is  set  to  a
           nonzero value whenever the field changes.

           The  function  set_max_field sets the maximum size for a dynamic field.
           An argument of 0 turns off any maximum size threshold for that field.

## RETURN VALUE

           The field_buffer  function  returns  NULL  on  error.   It  sets  errno
           according to their success:

           E_OK The routine succeeded.

           E_BAD_ARGUMENT
                Routine detected an incorrect or out-of-range argument.

           The field_status function returns TRUE or FALSE.

           The remaining routines return one of the following:

           E_OK The routine succeeded.

           E_SYSTEM_ERROR
                System error occurred (see errno(3)).

           E_BAD_ARGUMENT
                Routine detected an incorrect or out-of-range argument.

## NOTES

           When  configured for wide characters, field_buffer returns a pointer to
           temporary  storage  (allocated  and  freed  by   the   library).    The
           application should not attempt to modify the data.  It will be freed on
           the next call to field_buffer to return the same buffer.

## PORTABILITY

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

           The  set_max_field   function   checks   for   an   ncurses   extension
           O_INPUT_FIELD  which  allows a dynamic field to shrink if the new limit
           is smaller than the current field size.

## AUTHORS

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

## SEE ALSO

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

    ncurses 6.6                       2024-12-28             form_field_buffer(3x)