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  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
            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(3X)   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(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 fol-
       lowing:

       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.

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