form_field_buffer 3x 2024-03-16 ncurses 6.5 Library calls

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


       form_field_buffer - field buffer control


       #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);


       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

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

          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.


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

       E_OK The routine succeeded.

            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.

            System error occurred (see errno(3)).

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


       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.


       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.


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


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

ncurses 6.5                       2024-03-16             form_field_buffer(3x)