focal (3) field_validation.3form.gz

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 additional parameters:

            •   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.

                The library copies the string list, 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 additional parameters:

            •   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 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(3).

       TYPE_NUMERIC
            Numeric data (may have a decimal-point part).  This requires additional parameters:

            •   a third int argument controlling the precision,

            •   a fourth double argument constraining minimum value,

            •   and  a  fifth  double  constraining maximum value.  If your system supports locales, the decimal
                point character 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(3).

       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.

            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.  The library checks
            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.

            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 fieldtype(3FORM) 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(3)).

SEE ALSO

       ncurses(3NCURSES), form(3FORM), form_variables(3FORM).

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.

                                                                                         field_validation(3FORM)