form_field_validation(3X)												 form_field_validation(3X)

NAME

       form_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 precision, a fourth long argument con-
	    straining  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 precision, a fourth double argument con-
	    straining 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 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 expression (char *) third argument; the data is valid if the regular expression matches
	    it.  Regular expressions are in the format of regcomp(3X) and regexec(3X). 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  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.

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 ALSO

       curses(3X), 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 were not supported on Version 7 or BSD versions.

AUTHORS

       Juergen Pfeifer.  Manual pages and adaptation for new curses by Eric S. Raymond.

															 form_field_validation(3X)