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);
DESCRIPTION
The function set_field_type declares a data type for a
given form field. This is the type checked by validation
functions. The 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 to 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 or equal 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 locale's, the decimal point
character to be used must be the one specified by
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your locale. If the maximum value is less or equal
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(3) and
regexec(3X). Please notice that the regular expres-
sion 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 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(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 fol-
lowing:
E_OK The routine succeeded.
E_SYSTEM_ERROR
System error occurred (see errno).
SEE ALSOcurses(3), form(3X).
NOTES
The header file <form.h> automatically includes the header
file <curses.h>.
PORTABILITY
These routines emulate the System V forms library. They
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were not supported on Version 7 or BSD versions.
AUTHORS
Juergen Pfeifer. Manual pages and adaptation for new
curses by Eric S. Raymond.
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