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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |SEE ALSO |NOTES |PORTABILITY |AUTHORS |COLOPHON | |
form_fieldtype(3X)form_fieldtype(3X)form_fieldtype- define validation-field types
#include <form.h>FIELDTYPE *new_fieldtype(bool (* constfield_check)(FIELD *, const void *),bool (* constchar_check)(int, const void *));int free_fieldtype(FIELDTYPE *fieldtype);int set_fieldtype_arg(FIELDTYPE *fieldtype,void *(* constmake_arg)(va_list *),void *(* constcopy_arg)(const void *),void (* constfree_arg)(void *));int set_fieldtype_choice(FIELDTYPE *fieldtype,bool (* constnext_choice)(FIELD *, const void *),bool (* constprev_choice)(FIELD *, const void *));FIELDTYPE *link_fieldtype(FIELDTYPE *type1,FIELDTYPE *type2);
new_fieldtype The functionnew_fieldtypecreates a new field type usable for data validation. Its parameters are function pointers:field_check This function checks the validity of an entered data string whenever the user attempts to leave a field. It has two arguments: • The (FIELD *) argument is passed in so the validation predicate can see the field's buffer, sizes and other attributes. • The second argument is an argument-block structure, about which more below.char_check This function validates input characters as they are entered. The form library passes it the character to be checked and a pointer to an argument-block structure.free_fieldtype Thefree_fieldtypefunction frees the space allocated for a given validation type bynew_fieldtype.set_fieldtype_arg The functionset_fieldtype_argassociates three storage-management functions with a field type:make_arg This function is automatically applied to the list of arguments you giveset_field_typewhen attaching validation to a field. It stores the arguments in an allocated argument-block object which is used when validating input.copy_arg This function may be used by applications to copy argument- blocks.free_arg Frees an argument-block structure. You must supply themake_arg function. The other two are optional: you may supply NULL for them. In this case, the form library assumes thatmake_arg does not allocate memory but simply loads the argument into a single scalar value.set_fieldtype_choice The form driver requestsREQ_NEXT_CHOICEandREQ_PREV_CHOICE assume that the possible values of a field form an ordered set, and provide the forms user with a way to move through the set. Theset_fieldtype_choicefunction allows forms programmers to define successor and predecessor functions for the field type. These functions take the field pointer and an argument-block structure as arguments.link_fieldtype The functionlink_fieldtypecreates a new field type from the two given types. They are connected by an logical 'OR'.
The pointer-valued routines return NULL on error. They seterrno according to their success:E_OKThe routine succeeded.E_BAD_ARGUMENT Routine detected an incorrect or out-of-range argument.E_SYSTEM_ERROR System error occurred, e.g., malloc failure. The integer-valued routines return one of the following codes on error:E_OKThe routine succeeded.E_BAD_ARGUMENT Routine detected an incorrect or out-of-range argument.E_CONNECTED The field is already connected to a form.E_CURRENT The field is the current field.E_SYSTEM_ERROR System error occurred (seeerrno(3)).
curses(3X),form(3X),form_field_validation(3X).
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.
This page is part of thencurses (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 ⟨https://github.com/mirror/ncurses.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2023-03-12.) 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 isnot part of the original manual page), send a mail to man-pages@man7.orgform_fieldtype(3X)HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |