manpagez: man pages & more
man set_field_type(3)
Home | html | info | man
form_field_validation(3)                              form_field_validation(3)




NAME

       form_field_validation - data type validation for fields


SYNOPSIS

       #include <form.h>

       void *field_arg(const FIELD *field);
       FIELDTYPE *field_type(const FIELD *field);
       int set_field_type(FIELD *field, FIELDTYPE *type, ...);

       /* predefined field types */
       FIELDTYPE *TYPE_ALNUM;
       FIELDTYPE *TYPE_ALPHA;
       FIELDTYPE *TYPE_ENUM;
       FIELDTYPE *TYPE_INTEGER;
       FIELDTYPE *TYPE_NUMERIC;
       FIELDTYPE *TYPE_REGEXP;
       FIELDTYPE *TYPE_IPV4;


DESCRIPTION

       By default, no validation is done on form fields.  You can associate a
       form with with a field type, making the form library validate input.

   field_arg
       Returns a pointer to the field's argument block.  The argument block is
       an opaque structure containing a copy of the arguments provided in a
       set_field_type call.

   field_type
       Returns a pointer to the field type associated with the form field, i.e.,
       by calling set_field_type.

   set_field_type
       The function set_field_type associates a field type with a given form
       field.  This is the type checked by validation functions.  Most field
       types are configurable, via arguments which the caller provides when
       calling set_field_type.

       Several field types are predefined by the form library.

   Predefined types
       It is possible to set up new programmer-defined field types.  Field types
       are implemented via the FIELDTYPE data structure, which contains several
       pointers to functions.

       See the form_fieldtype(3X) manual page, which describes functions which
       can be used to construct a field-type dynamically.

       The predefined types are as follows:

       TYPE_ALNUM
            Alphanumeric data.  Required parameter:

            o   a third int argument, a minimum field width.

       TYPE_ALPHA
            Character data.  Required parameter:

            o   a third int argument, a minimum field width.

       TYPE_ENUM
            Accept one of a specified set of strings.  Required parameters:

            o   a third (char **) argument pointing to a string list;

            o   a fourth int flag argument to enable case-sensitivity;

            o   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).  Required
            parameters:

            o   a third int argument controlling the precision,

            o   a fourth long argument constraining minimum value,

            o   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).  Required parameters:

            o   a third int argument controlling the precision,

            o   a fourth double argument constraining minimum value,

            o   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.  Required parameter:

            o   a third argument, a regular expression (char *) string.  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.  Required parameter:

            o   none

            The form library checks whether or not the buffer has the form
            a.b.c.d, where a, b, c, and d are numbers in the range 0 to 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.


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

       curses(3X), form(3X), form_fieldtype(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(3)

ncurses 6.4 - Generated Tue Jan 3 10:24:04 CST 2023
© manpagez.com 2000-2024
Individual documents may contain additional copyright information.