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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 DEBIAN

smigetclassmodule

smi_class(3)						SMI Management Information Library					      smi_class(3)

NAME

       smiGetClass smiGetFirstClass, smiGetNextClass, smiGetClassModule, smiGetParentClass, smiIsClassScalar - SMI class information routines

SYNOPSIS

       #include <smi.h>

       SmiClass *smiGetClass(SmiModule *smiModulePtr, char *name);

       SmiClass *smiGetFirstClass(SmiModule *smiModulePtr);

       SmiClass *smiGetNextClass(SmiClass *smiClassPtr);

       SmiClass *smiGetParentClass(SmiClass *smiClassPtr);

       SmiModule *smiGetClassModule(SmiClass *smiClassPtr);

       int smiIsClassScalar(SmiClass *smiClassPtr);

       typedef struct SmiClass {
	   SmiIdentifier       name;
	   SmiDecl	       decl;
	   SmiStatus	       status;
	   char 	       *description;
	   char 	       *reference;
       } SmiClass;

DESCRIPTION

       These functions retrieve information on a SMIng class definition (SMIng).

       smiGetClass(SmiModule  *smiModulePtr,char  *name) returns a pointer to struct SmiClass that represents the class with the given name in the
       given module(smiModulePtr ), or NULL if the class with the given name does not exist.

       smiGetFirstClass(SmiModule *smiModulePtr) and smiGetNextClass(SmiClass *smiClassPtr) are used to iterate through the classes of the  module
       given by smiModulePtr. They return a pointer to struct SmiClass that represents a class or NULL if there are no classes left in the module,
       or error has occurred.

       smiGetClassModule(SmiClass *smiClassPtr) returns a pointer to struct SmiModule, of the module containing the given class.

       smiGetParentClass(SmiClass *smiClassPtr) returns a pointer to struct SmiClass pointing to the parent of the given smiClassPtr, or  NULL	if
       the class is not derived.

       smiIsClassScalar(SmiClass  *smiClassPtr)  returns int 1 if the class is scalar(its unique statement contains an empty list) or 0 otherwise.
       This method can be used in conjunction with smiGetFirstUniqueAttribute() to determine whether the class is meant to be  instantiated  sepa-
       rately (has unique statement with nonempty list), or if it is meant to be used as part of another class (has no unique statement).

FILES

       ${prefix}/include/smi.h	  SMI library header file

SEE ALSO

       libsmi(3), smi_module(3), smi.h

AUTHOR

       (C) 2007 Kaloyan Kanev, Jacobs University, Germany <k.kanev@jacobs-university.de>

								 February 10, 2007						      smi_class(3)
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