form_field_buffer(3x) — Linux manual page


form_field_buffer(3X)                              form_field_buffer(3X)

NAME         top

       form_field_buffer - field buffer control

SYNOPSIS         top

       #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         top

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

          •   Buffer 0 is the displayed value of the field.

          •   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:

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

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

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

          •   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.

          •   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         top

       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.

SEE ALSO         top

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

NOTES         top

       The header file <form.h> automatically includes the header file

       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.  <curses.h>.

PORTABILITY         top

       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         top

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

COLOPHON         top

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