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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 argu-ment argument
            ment 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 using 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 max-imum maximum
            imum  value.  If the maximum value is less than or equal to the minimum value, the range is sim-ply simply
            ply ignored. On return the field buffer is formatted according to the printf  format  specifica-tion specification
            tion  ".*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 pre-cision, precision,
            cision,  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 expression (char *) third  argument;  the  data  is
            valid  if  the  regular expression matches it.  Regular expressions 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]*$" always means that you
            have to fill all eight positions with digits. If you want to allow fewer digits, you may use for
            example "^[0-9]* *$" 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 validated. Please note that
            this  is  an ncurses extension. This field type may not be available in other curses implementa-tions. implementations.
            tions.

       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  ver-sions. versions.
       sions.

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



                                                                                   form_field_validation(3X)