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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  prede-
       fined 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 specify-
            ing 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  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's man-page.

       TYPE_NUMERIC
            Numeric data (may have a decimal-point part). Requires a third int
            argument controlling the precision, a fourth double argument  con-
            straining  minimum  value, and a fifth double constraining maximum
            value. If your system supports locales, the decimal point  charac-
            ter  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 preci-
            sion 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 addi-
            tional 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 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 func-
       tion 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), 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 sup-
       ported on Version 7 or BSD versions.


AUTHORS

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



                                                     form_field_validation(3x)