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 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). Please
notice that the string list is copied. 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 a third int argument controlling the preci-
sion, 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's man-page.
TYPE_NUMERIC
Numeric data (may have a decimal-point part).
Requires a third int argument controlling the preci-
sion, a fourth double argument constraining minimum
value, and a fifth double constraining maximum value.
If your system supports locales, the decimal point
character to be used 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's
man-page.
TYPE_REGEXP
Regular expression data. Requires a regular expres-
sion (char *) third argument; the data is valid if
the regular expression matches it. Regular expres-
sions are in the format of regcomp and regexec.
Please notice that the regular expression must match
the whole field. If you have for example an eight
character wide field, a regular expression "^[0-9]*$"
always means that you have to fill all eight posi-
tions with digits. If you want to allow fewer digits,
you may use for example "^[0-9]* *$" 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. It is checked 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 vali-
dated. Please note that 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 fol-
lowing:
E_OK The routine succeeded.
E_SYSTEM_ERROR
System error occurred (see errno).
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.
form_field_validation(3x)