NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | NOTES | PORTABILITY | AUTHORS | COLOPHON

form_field_validation(3X)                          form_field_validation(3X)

NAME         top

       form_field_validation - data type validation for fields

SYNOPSIS         top

       #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         top

       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
       form_fieldtype(3X) manual page.

RETURN VALUE         top

       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         top

       curses(3X), form(3X), form_variables(3X).

NOTES         top

       The header file <form.h> automatically includes the header file
       <curses.h>.

PORTABILITY         top

       These routines emulate the System V forms library.  They were not
       supported on Version 7 or BSD versions.

AUTHORS         top

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

COLOPHON         top

       This page is part of the ncurses (new curses) project.  Information
       about the project can be found at 
       ⟨https://www.gnu.org/software/ncurses/ncurses.html⟩.  If you have a
       bug report for this manual page, send it to
       bug-ncurses-request@gnu.org.  This page was obtained from the
       project's upstream Git mirror of the CVS repository
       ⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2019-09-26.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2019-09-22.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org

                                                   form_field_validation(3X)