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 prede-
fined 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:
o a third (char **) argument pointing to a string list;
o a fourth int flag argument to enable case-sensitivity;
o 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 addi-
tional parameters:
o a third int argument controlling the precision,
o a fourth long argument constraining minimum value,
o 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 addi-
tional parameters:
o a third int argument controlling the precision,
o a fourth double argument constraining minimum value,
o 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 addi-
tional 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 func-
tion 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 sup-
ported on Version 7 or BSD versions.
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S.
Raymond.
form_field_validation(3x)