form_field_validation(3)form_field_validation(3)NAMEform_field_validation - data type validation for fields
SYNOPSIS
#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;
DESCRIPTION
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 not copied, only a reference to it is stored in the field.
So you should avoid using 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 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's man-page.
TYPE_NUMERIC
Numeric data (may have a decimal-point part). Requires 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 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 expression (char *)
third argument; the data is valid if the regular expression
matches it. Regular expressions 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]*$" always means that you have
to fill all eight positions with digits. If you want to allow
fewer digits, you may use for example "^[0-9]* *$" 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. 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 validated. 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(3) manual page.
RETURN VALUE
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).
SEE ALSOcurses(3), form(3).
NOTES
The header file <form.h> automatically includes the header file
<curses.h>.
PORTABILITY
These routines emulate the System V forms library. They were not
supported on Version 7 or BSD versions.
AUTHORS
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S.
Raymond.
March 1, 2011
