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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | NOTES | PORTABILITY | AUTHORS | COLOPHON |
form_field_validation(3X) form_field_validation(3X)
form_field_validation - data type validation for fields
#include <form.h>
int set_field_type(FIELD *field, FIELDTYPE *type, ...);
FIELDTYPE *field_type(const FIELD *field);
void *field_arg(const FIELD *field);
FIELDTYPE *TYPE_ALNUM;
FIELDTYPE *TYPE_ALPHA;
FIELDTYPE *TYPE_ENUM;
FIELDTYPE *TYPE_INTEGER;
FIELDTYPE *TYPE_NUMERIC;
FIELDTYPE *TYPE_REGEXP;
FIELDTYPE *TYPE_IPV4;
The function set_field_type declares a data type for a given form
field. This is the type checked by validation functions. The
predefined types are as follows:
TYPE_ALNUM
Alphanumeric data. Requires a third int argument, a minimum
field width.
TYPE_ALPHA
Character data. Requires a third int argument, a minimum field
width.
TYPE_ENUM
Accept one of a specified set of strings. Requires additional
parameters:
· a third (char **) argument pointing to a string list;
· a fourth int flag argument to enable case-sensitivity;
· and a fifth int flag argument specifying whether a partial
match must be a unique one. If this flag is off, a prefix
matches the first of any set of more than one list elements
with that prefix.
The library copies the string list, so you may use a list
that lives in automatic variables on the stack.
TYPE_INTEGER
Integer data, parsable to an integer by atoi(3). Requires
additional parameters:
· a third int argument controlling the precision,
· a fourth long argument constraining minimum value,
· and a fifth long constraining maximum value. If the maximum
value is less than or equal to the minimum value, the range
is simply ignored. On return, the field buffer is formatted
according to the printf format specification “.*ld”, where
the “*” is replaced by the precision argument.
For details of the precision handling see printf(3).
TYPE_NUMERIC
Numeric data (may have a decimal-point part). This requires
additional parameters:
· a third int argument controlling the precision,
· a fourth double argument constraining minimum value,
· and a fifth double constraining maximum value. If your
system supports locales, the decimal point character must be
the one specified by your locale. If the maximum value is
less than or equal to the minimum value, the range is simply
ignored.
On return, the field buffer is formatted according to the
printf format specification “.*f”, where the “*” is replaced
by the precision argument.
For details of the precision handling see printf(3).
TYPE_REGEXP
Regular expression data. Requires a regular expression (char *)
third argument. The data is valid if the regular expression
matches it.
Regular expressions are in the format of regcomp and regexec.
The regular expression must match the whole field. If you have
for example, an eight character wide field, a regular expression
"^[0-9]*$" always means that you have to fill all eight
positions with digits. If you want to allow fewer digits, you
may use for example "^[0-9]* *$" which is good for trailing
spaces (up to an empty field), or "^ *[0-9]* *$" which is good
for leading and trailing spaces around the digits.
TYPE_IPV4
An Internet Protocol Version 4 address. This requires no
additional argument. The library checks whether or not the
buffer has the form a.b.c.d, where a,b,c and d are numbers
between 0 and 255. Trailing blanks in the buffer are ignored.
The address itself is not validated.
This is an ncurses extension; this field type may not be
available in other curses implementations.
It is possible to set up new programmer-defined field types. See the
form_fieldtype(3X) manual page.
The functions field_type and field_arg return NULL on error. The
function set_field_type returns one of the following:
E_OK The routine succeeded.
E_SYSTEM_ERROR
System error occurred (see errno(3)).
curses(3X), form(3X), form_variables(3X).
The header file <form.h> automatically includes the header file
<curses.h>.
These routines emulate the System V forms library. They were not
supported on Version 7 or BSD versions.
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric
S. Raymond.
This page is part of the ncurses (new curses) project. Information
about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to
bug-ncurses-request@gnu.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-09.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
form_field_validation(3X)