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Full Discussion: C++ class definition with a member of the same class
Top Forums Programming C++ class definition with a member of the same class Post 302430729 by Corona688 on Friday 18th of June 2010 01:15:48 PM
Old 06-18-2010
Quote:
Originally Posted by pogdorica
Hi, i have a question about C++. Is it possible to declare a class with a member ot the same class?
I don't think you can. Think about it: Wouldn't that class inside the class, also have a class inside the class? Which would also have a class inside the class. etc. etc. etc. If you want different things to have different members, they have to be different structures.

This doesn't even work in C. Observe:
Code:
typedef struct whatever
{
    int a;
    struct whatever s;
} whatever;

will give an error since you can't nest that way.

You can cheat by using a pointer. The compiler will let you make pointers to incomplete types since a pointer's always the same size.

Code:
typedef struct linkedlist
{
    int payload;
    struct linkedlist *next;
} linkedlist;

That way it only allocates the size of the pointer, not the entire struct, avoiding the infinite recursion. This means you have to explicitly allocate memory to it later to use it, of course.
 

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LEARN ABOUT OSF1

class_add

class_add(3)						     Library Functions Manual						      class_add(3)

NAME

       class_add - Add a member to an existing class

LIBRARY

       Standard C Library (libclass.a)

SYNOPSIS

       #include <apar_types.h> #include <sys/class.h>

       class_add(class_apar_handle_t, *class_name, type, member, force);
	       class_apar_handle_t handle
	       class_name char
	       type int
	       member int
	       force int

PARAMETERS

       The  partition  descriptor  returned by class_open().  Name of the class to which the new member is to be added.  Member type as defined in
       <sys/class.h>.  For example: CL_TYPE_UID.  Identifier representing type.  TRUE/FALSE - If a member is found in  another	class,	force  the
       member to be moved to class_name

DESCRIPTION

       Add a member to an existing class.  If the member is found in another class, the member will be moved to the new class if force is TRUE.

       Note that the calling process must have root access privileges.

RETURN VALUES

       Operation  successfully	completed.  An invalid partition handle was specified.	Not super user.  Permission denied.  The class_name is not
       an ASCII string.  The class_name does not exist.  No space is available in class_name.  A member of type type is already in class_name.	 A
       member  of  type  type  is  in another class.  This value is returned only if force is FALSE.  Operations on the default class are not sup-
       ported.

SEE ALSO

       Functions:class_init(3), class_change(3), class_create(3), class_close(3), class_configure(3),  class_get_config_stats(3),  class_close(3),
       class_delete(3),  class_destroy(3),  class_disable(3), class_enable(3), class_save_database(3), class_restore_database(3), class_load_data-
       base(3), class_change_name(3),  class_database_file_exists(3),  class_database_name(3),	class_database_modified(3),  class_get_classes(3),
       class_get_class_members(3),

       Commands:class_admin(8), runclass(1), class_scheduling(4)

       Other: The System Administration guide.	delim off

																      class_add(3)
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