form_field_validation()

data type validation for fields 

Curses Function


SYNOPSIS

#include <form.h>

int set_field_type(FIELD *field, FIELDTYPE *type, ...);

FIELDTYPE *field_type(const FIELD *field);

void *field_arg(const FIELD *field);


DESCRIPTION

The function set_field_type() declares a data type for a given form field. This is the type checked by validation functions. The 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 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 to use a list that lives in automatic variables on the stack.

TYPE_INTEGER 

Integer data, parsable to an integer by atoi(). Requires a third int precision argument that sets zero-padding, a fourth int argument constraining minimum value, and a fifth int constraining maximum value.

TYPE_NUMERIC 

Numeric data (may have a decimal-point part). Requires a third int precision argument that sets zero-padding, 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.

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 implementations.

It is possible to set up new programmer-defined field types. See the form_fieldtype() reference page.


RETURN VALUES

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.


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.


AVAILABILITY

PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition


SEE ALSO

Functions:
curses(), form()


PTC MKS Toolkit 10.1 Documentation Build 15.