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field_arg(3)

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 specify-
	    ing 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
	    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 format-
	    ted 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 charac-
	    ter 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.

	    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.  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(3X) manual page.

RETURN VALUE

       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).

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  sup-
       ported on Version 7 or BSD versions.

AUTHORS

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

						     form_field_validation(3X)

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