form_field_validation − data type validation for fields
#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;
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 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 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 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. 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’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 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 fieldtype(3FORM) manual page.
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).
ncurses(3NCURSES), form(3FORM), form_variables(3FORM).
The header file <form.h> automatically includes the header file <curses.h>.
These routines emulate the System V forms library. They were not supported on Version 7 or BSD versions.
Juergen Pfeifer. Manual pages and adaptation for new curses by Eric S. Raymond.
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.