field_buffer(3FORM) Library calls field_buffer(3FORM)
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:
• Buffer 0 is the displayed value of the field.
• Other numbered buffers may be allocated by applications through
the nbuf argument of (see field_new(3FORM)) but are not manipu-
lated 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 field.
• 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
The field_buffer function returns NULL on error. It sets errno accord-
ing 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 sup-
ported 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
ncurses(3NCURSES) and related pages whose names begin “form_” for de-
tailed descriptions of the entry points.
ncurses 6.5 2024-12-28 field_buffer(3FORM)
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