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form_field_validation 3x



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);

       FIELDTYPE *TYPE_ALNUM;
       FIELDTYPE *TYPE_ALPHA;
       FIELDTYPE *TYPE_ENUM;
       FIELDTYPE *TYPE_INTEGER;
       FIELDTYPE *TYPE_NUMERIC;
       FIELDTYPE *TYPE_REGEXP;
       FIELDTYPE *TYPE_IPV4;


DESCRIPTION

       The  function  set_field_type  declares  a data type for a
       given form field.  This is the type checked by  validation
       functions.  The predefined 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 copied. 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  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 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'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 locales, the decimal point
            character to be used 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'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  and  regexec.
            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]*$"
            always means that you have to fill  all  eight  posi-
            tions with digits. If you want to allow fewer digits,
            you may use for example "^[0-9]* *$"  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), form_variables(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)

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