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Can you write object oriented code in C? Especially with regard to polymorphism.

See also: http://stackoverflow.com/questions/415452/object-orientation-in-c

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@Camilo Martin: I intentionally asked can not should. I'm not actually interested in using OOP in C. However, by seeing OO solutions in C, I/we stand to learn more about the limits and/or flexibility of C and also about creative ways to implement and use polymorphism. –  Dinah Nov 24 '10 at 16:17
OO is just a pattern. Check here, it can even be done in .bat Files: dirk.rave.org/chap9.txt (any pattern can be applied to any programming language if you are interested enough, I think). This is good food for thought, though. And probably a lot can be learnt from applying such patterns we take for granted on languages that don't have them. –  Camilo Martin Nov 24 '10 at 19:47
GTK - 'scuse me, GObject - is actually a pretty good example of OOP (sorta) in C. So, to answer @Camilo, for C interpoliability. –  new123456 Dec 14 '10 at 22:59
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31 Answers

up vote 143 down vote accepted

Yes. In fact Axel Schreiner provides his book "Object Orientated Programming in ANSI-C" for free which covers the subject quite thoroughly.

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While the concepts in this book are solids, you'll lose type safety. –  diapir Jun 30 '09 at 20:29
Before what we know as design patterns, was the design pattern known as "object orientation"; same with garbage collection, and other such. They are so ingrained now, we tend to forget, when they were first being devised, it was in much the same way as with what we think of as design patterns today –  George Jempty Aug 27 '10 at 22:46
The link to the book is broken. Does anybody know alternate location? Tried googling for it without success :( –  varun Mar 4 '12 at 18:06
You can get it directly from the author's site: cs.rit.edu/~ats/books/ooc.pdf other papers from same author: cs.rit.edu/~ats/books/index.html –  pakman Jul 28 '12 at 0:33
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Since you're talking about polymorphism then yes, you can, we were doing that sort of stuff years before C++ came about.

Basically you use a struct to hold both the data and a list of function pointers to point to the relevant functions for that data.

So, in a communications class, you would have an open, read, write and close call which would be maintained as four function pointers in the structure, alongside the data for an object, something like:

typedef struct {
    int (*open)(void *self, char *fspec);
    int (*close)(void *self);
    int (*read)(void *self, void *buff, size_t max_sz, size_t *p_act_sz);
    int (*write)(void *self, void *buff, size_t max_sz, size_t *p_act_sz);
    // And data goes here.
} tCommClass;

tCommClass commRs232;
commRs232.open = &rs232Open;
: :
commRs232.write = &rs232Write;

tCommClass commTcp;
commTcp.open = &tcpOpen;
: :
commTcp.write = &tcpWrite;

Of course, those code segments above would actually be in a "constructor" such as rs232Init().

When you 'inherit' from that class, you just change the pointers to point to your own functions. Everyone that called those functions would do it through the function pointers, giving you your polymorphism:

int stat = (commTcp.open)(commTcp, "bigiron.box.com:5000");

Sort of like a manual vtable.

You could even have virtual classes by setting the pointers to NULL -the behaviour would be slightly different to C++ (a core dump at run-time rather than an error at compile time).

Here's a piece of sample code that demonstrates it. First the top-level class structure:

#include <stdio.h>

// The top-level class.

typedef struct _tCommClass {
    int (*open)(struct _tCommClass *self, char *fspec);
} tCommClass;

Then we have the functions for the TCP 'subclass':

// Function for the TCP 'class'.

static int tcpOpen (tCommClass *tcp, char *fspec) {
    printf ("Opening TCP: %s\n", fspec);
    return 0;
static int tcpInit (tCommClass *tcp) {
    tcp->open = &tcpOpen;
    return 0;

And the HTTP one as well:

// Function for the HTTP 'class'.

static int httpOpen (tCommClass *http, char *fspec) {
    printf ("Opening HTTP: %s\n", fspec);
    return 0;
static int httpInit (tCommClass *http) {
    http->open = &httpOpen;
    return 0;

And finally a test program to show it in action:

// Test program.

int main (void) {
    int status;
    tCommClass commTcp, commHttp;

    // Same 'base' class but initialised to different sub-classes.

    tcpInit (&commTcp);
    httpInit (&commHttp);

    // Called in exactly the same manner.

    status = (commTcp.open)(&commTcp, "bigiron.box.com:5000");
    status = (commHttp.open)(&commHttp, "http://www.microsoft.com");

    return 0;

This produces the output:

Opening TCP: bigiron.box.com:5000
Opening HTTP: http://www.microsoft.com

so you can see that the different functions are being called, depending on the sub-class.

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Encapsulation is pretty easy, polymorphism is doable - but inheritence is tricky –  Martin Beckett Jul 19 '10 at 16:10
+1 for "...slightly different...(core dump at run-time rather than error at compile time)" –  Michael Mior Oct 12 '10 at 20:06
lwn.net recently published an article titled Object Oriented design Patterns in the kernel on the subject of stucts similar to the above answer - that is, a struct containing function pointers, or a pointer to a struct that has functions that take a pointer to the struct with the data we are working with as a parameter. –  misterMatt Jun 5 '11 at 0:51
Excellent SO answer! The examples and explanation are plain and develop the idea effectively with minimal obscurity! –  Limited Atonement May 29 '13 at 21:45
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Namespaces are often done by doing:

stack_push(thing *)

instead of

stack::push(thing *)

To make a c struct into something like a c++ class you can turn:

class stack {
        void push(thing *);
        thing * pop();
        static int this_is_here_as_an_example_only;


struct stack {
     struct stack_type * my_type;
     // put the stuff that you put after private: here
struct stack_type {
     void (* construct)(struct stack * this); // this takes uninitialized memory
     struct stack * (* operator_new)(); // this allocates a new struct, passes it to construct, and then returns it
     void (*push)(struct stack * this, thing * t); // pushing t onto this stack
     thing * (*pop)(struct stack * this); // pops the top thing off the stack and returns it
     int this_is_here_as_an_example_only;
}Stack = {
    .construct = stack_construct,
    .operator_new = stack_operator_new,
    .push = stack_push,
    .pop = stack_pop
 // all of these functions are assumed to be defined somewhere else

and do:

struct stack * st = Stack.operator_new(); // make a new stack
if (!st) {
   // do something about it
} else {
   // you can use the stack
   stack_push(st, thing0); // This is a non-virtual call
   Stack.push(st, thing1); // This is like casting *st to a Stack (which it already is) and doing the push
   st->my_type.push(st, thing2); // This is a virtual call

I didn't do the destructor or delete, but it follows the same pattern.

this_is_here_as_an_example_only is like a static class variable -- shared among all instances of a type. All methods are really static, except that some take a this *

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@Chris Lutz: Thanks. Fixed. –  nategoose Apr 28 '10 at 21:50
I like the concept of having a struct for the class. But how about a generic Class struct? That would make the OO C more dynamic than C++. How about that? By the way, +1. –  Linuxios Jul 28 '12 at 20:21
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I've seen it done. I wouldn't recommend it. C++ originally started this way as a preprocessor that produced C code as an intermediate step.

Essentially what you end up doing is create a dispatch table for all of your methods where you store your function references. Deriving a class would entail copying this dispatch table and replacing the entries that you wanted to override, with your new "methods" having to call the original method if it wants to invoke the base method. Eventually, you end up rewriting C++.

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"Eventually, you end up rewriting C++" I wondered if/feared that would be the case. –  Dinah Apr 14 '10 at 15:53
Or, you might end up rewriting Objective C, which would be a much more attractive outcome. –  Prof. Falken Nov 5 '10 at 12:15
There is the class-less flavour of OOP, such as in Javascript, where the guru says: "We don't need classes to make lots of similar objects." But I fear this is not easy to achieve in C. Not (yet) in a position to tell, though. (Is there a clone() routine to clone a struct?) –  Lumi Jun 11 '11 at 21:32
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I believe that besides being useful in its own right, implementing OOP in C is an excellent way to learn OOP and understand its inner workings. Experience of many programmers has shown that to use a technique efficiently and confidently, a programmer must understand how the underlying concepts are ultimately implemented. Emulating classes, inheritance, and polymorphism in C teaches just this.

To answer the original question, here are a couple resources that teach how to do OOP in C:

EmbeddedGurus.com blog post "Object-based programming in C" shows how to implement classes and single inheritance in portable C: http://embeddedgurus.com/state-space/2008/01/object-based-programming-in-c/

Application Note ""C+"—Object Oriented Programming in C" shows how to implement classes, single inheritance, and late binding (polymorphism) in C using preprocessor macros: http://www.state-machine.com/resources/cplus_3.0_manual.pdf, the example code is available from http://www.state-machine.com/resources/cplus_3.0.zip

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Sure that is possible. This is what GObject, the framework where all of gtk+ and gnome are based on, does. Read this: http://en.wikipedia.org/wiki/GObject.

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The C stdio FILE sub-library is an excellent example of how to create abstraction, encapsulation, and modularity in unadulterated C.

Inheritance and polymorphism - the other aspects often considered essential to OOP - do not necessarily provide the productivity gains they promise and reasonable arguments have been made that they can actually hinder development and thinking about the problem domain.

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Trivial example with a Animal and Dog, what you do is mirror C++'s vtable mechanism (largely anyway). You also separate allocation and instantiation (Animal_Alloc, Animal_New) so we don't call malloc() multiple times. We must also explicitly pass the this pointer around.

If you were to do non virtual functions, that's trival. You just don't add them to the vtable and static functions don't require a this pointer. Multiple inheritance generally requires multiple vtables to resolve ambiguities.

Also, you should be able to use setjmp/longjmp to do exception handling.

struct Animal_Vtable{
	typedef void (*Walk_Fun)(struct Animal *a_This);
	typedef struct Animal * (*Dtor_Fun)(struct Animal *a_This);

	Walk_Fun Walk;
	Dtor_Fun Dtor;

struct Animal{
	Animal_Vtable vtable;

	char *Name;

struct Dog{
	Animal_Vtable vtable;

	char *Name; // mirror member variables for easy access
	char *Type;

void Animal_Walk(struct Animal *a_This){
	printf("Animal (%s) walking\n", a_This->Name);

struct Animal* Animal_Dtor(struct Animal *a_This){
	return a_This;

Animal *Animal_Alloc(){
	return (Animal*)malloc(sizeof(Animal));

Animal *Animal_New(Animal *a_Animal){
	a_Animal->vtable.Walk = Animal_Walk;
	a_Animal->vtable.Dtor = Animal_Dtor;
	a_Animal->Name = "Anonymous";
	return a_Animal;

void Animal_Free(Animal *a_This){


void Dog_Walk(struct Dog *a_This){
	printf("Dog walking %s (%s)\n", a_This->Type, a_This->Name);

Dog* Dog_Dtor(struct Dog *a_This){
	// explicit call to parent destructor


	return a_This;

Dog *Dog_Alloc(){
	return (Dog*)malloc(sizeof(Dog));

Dog *Dog_New(Dog *a_Dog){
	// explict call to parent constructor

	a_Dog->Type = "Dog type";
	a_Dog->vtable.Walk = (Animal_Vtable::Walk_Fun) Dog_Walk;
	a_Dog->vtable.Dtor = (Animal_Vtable::Dtor_Fun) Dog_Dtor;

	return a_Dog;

int main(int argc, char **argv){
	base class: 
	Animal *a_Animal = Animal_New(Animal_Alloc());
	Animal *a_Animal = (Animal*)Dog_New(Dog_Alloc());



PS. This is tested on a C++ compiler, but it should be easy to make it work on a C compiler.

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There are several techniques that canbe used. The most important one is more how to split the project. We use in our project an interface that is declared in a .h file and the implementation of the object in a .c file. The important part is that all modules that include the .h file see only an object as a void *, the .c file is the only module who knows the internas of the structure.

Something like that for a class we name FOO as example:

in the .h file

#ifndef FOO_H_
#define FOO_H_

 typedef struct FOO_type FOO_type;     /* That's all the rest of the program knows about FOO */

/* Declaration of accessors, functions */
 FOO_type *FOO_new(void);
 void FOO_free(FOO_type *this);
 void FOO_dosomething(FOO_type *this, param ...):
 char *FOO_getName(FOO_type *this, etc);

The C implementation file will be something like that

#include <stdlib.h>
#include "FOO.h"

struct FOO_type {

 FOO_type *FOO_new(void)
    FOO_type *this = calloc(1, sizeof (FOO_type));

    FOO_dosomething(this, );
    return this;        

So I give explicitly the pointer to an object to every function of that module. A C++ compiler does it implicitely, in C we write it explicitly out.

I use really this in my programs, to make sure that my program does not compile in C++ and it has the fine property of being in another color in my syntax highlighting editor.

The fields of the FOO_struct can be modified in one module and another module doesn't even need to be recompiled to be still usable.

With that style I handle already a big part of the advantages of OOP (data encapsulation). By using function pointers, it's even easy to implement something like inheritance, but honestly, it's really only rarely useful.

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If you do typedef struct FOO_type FOO_type instead of a typedef to void in the header you get the added benefit of type checking, while still not exposing your structure. –  Scott Wales Apr 29 '10 at 0:38
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This has been interesting to read. I have been pondering the same question myself, and the benefits of thinking about it are this:

  • Trying to imagine how to implement OOp concepts in a non-oop language helps me understand the strengths of the OOp language (in my case, C++). This helps give me better judgement about whether to use C or C++ for a given type of application -- where the benefits of one out-weighs the other.

  • In my browsing the web for information and opinions on this I found an author who was writing code for an embedded processor and only had a C compiler available: http://www.eetimes.com/discussion/other/4024626/Object-Oriented-C-Creating-Foundation-Classes-Part-1 In his case, analyzing and adapting OOP concepts in plain C was a valid pursuit. It appears he was open to sacrificing some OOP concepts due to the performance overhead hit resulting from attempting to implement them in C.

The lesson I've taken is, yes it can be done to a certain degree, and yes, there are some good reasons to attempt it.

In the end the machine is twiddling stack pointer bits, making the program counter jump around and calculating memory access operations. From the efficiency standpoint, the less of these calculations done by your program, the better... but sometimes we have to pay this tax simply so we can organize our program in a way that makes it least susceptible to human error. The OOP language compiler strives to optimize both aspects. The programmer has to be much more careful implementing these concepts in a language like C.

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If you are convinced that an OOP approach is superior for the problem you are trying to solve, why would you be trying to solve it with a non-OOP language? It seems like you're using the wrong tool for the job. Use C++ or some other object-oriented C variant language.

If you are asking because you are starting to code on an already existing large project written in C, then you shouldn't try to force your own (or anyone else's) OOP paradigms into the project's infrastructure. Follow the guidelines that are already present in the project. In general, clean APIs and isolated libraries and modules will go a long way towards having a clean OOP-ish design.

If, after all this, you really are set on doing OOP C, read this (PDF).

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Not really answering the question... –  Brian Postow Apr 28 '10 at 21:29
@Brian, the link to the PDF would appear to answer the question directly, although I haven't had time to check for myself. –  Mark Ransom Apr 28 '10 at 21:40
The link to the PDF appears to be an entire textbook on the subject... A beautiful proof, but it doesn't fit into the margin... –  Brian Postow Apr 28 '10 at 22:46
yes, answer the question. it's perfectly valid to ask how to use a language in a particular way. there was no request for opinions on other languages.... –  ttt Apr 28 '10 at 23:50
@Brian & Tim Ring: The question asked for book recommendations on a topic; I gave him a link to a book that specifically addresses this topic. I also gave my opinion on why the approach to the problem may not be optimal (which I think many people on here seem to agree with, based on votes and other comments/answers). Do you have any suggestions for improving my answer? –  RarrRarrRarr Apr 29 '10 at 0:16
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Check out GObject. It's meant to be OO in C and one implementation of what you're looking for. If you really want OO though, go with C++ or some other OOP language. GObject can be really tough to work with at times if you're used to dealing with OO languages, but like anything, you'll get used to the conventions and flow.

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You may find it helpful to look at Apple's documentation for its Core Foundation set of APIs. It is a pure C API, but many of the types are bridged to Objective-C object equivalents.

You may also find it helpful to look at the design of Objective-C itself. It's a bit different from C++ in that the object system is defined in terms of C functions, e.g. objc_msg_send to call a method on an object. The compiler translates the square bracket syntax into those function calls, so you don't have to know it, but considering your question you may find it useful to learn how it works under the hood.

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Object oriented C, can be done, I've seen that type of code in production in Korea, and it was the most horrible monster I'd seen in years (this was like last year(2007) that I saw the code). So yes it can be done, and yes people have done it before, and still do it even in this day and age. But I'd recommend C++ or Objective-C, both are languages born from C, with the purpose of providing object orientation with different paradigms.

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Yes, you can. People were writing Object Oriented C before C++ or Objective C came on the scene. Both C++ and Objective C were, in parts, attempts to take some of the OO concepts used in C and formalize them as part of the language.

Here's a really simple program that shows how you can make something that looks-like/is a method call (there are better ways to do this, this is just proof the language supports the concepts)


struct foobarbaz{
    int one;
    int two;
    int three;
    int (*exampleMethod)(int, int);

int addTwoNumbers(int a, int b){
    return a+b;

int main()
    //define the function pointer    
    int (*pointerToFunction)(int, int) = addTwoNumbers;         

    //lets make sure we can call the pointer
    int test = (*pointerToFunction)(12,12); 
    printf ("test: %u \n",  test);

    //now, define an instance of our struct
    //and add some default values
    struct foobarbaz fbb;
    fbb.one   = 1;
    fbb.two   = 2;
    fbb.three = 3;   

    //now add a "method"
    fbb.exampleMethod = addTwoNumbers;

    //try calling the method
    int test2 = fbb.exampleMethod(13,36);    
    printf ("test2: %u \n",  test2);   

    return 0;
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Of course, it just won't be a pretty as using a language with built in support. I've even written "object oriented assembler".

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You can fake it using function pointers, and in fact, I think it is theoretically possible to compile C++ programs into C.

However, it rarely makes sense to force a paradigm on a language rather than to pick a language that uses a paradigm.

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The very first C++ compiler did exactly that - it converted the C++ code into equivalent (but ugly and non-human-readable) C code, which was then compiled by the C compiler. –  Adam Rosenfield Dec 9 '08 at 6:05
You can also do the same thing with LLVM and the C backend. –  Zifre Mar 31 '09 at 17:47
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There is an example of inheritance using C in Jim Larson's 1996 talk given at the Section 312 Programming Lunchtime Seminar here: High and Low-Level C.

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Which articles or books are good to use OOP concepts in C?

Dave Hanson's C Interfaces and Implementations is excellent on encapsulation and naming and very good on use of function pointers. Dave does not try to simulate inheritance.

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One thing you might want to do is look into the implementation of the Xt toolkit for xwindows. Sure it is getting long in the tooth but many of the structures used were designed to work in an OO fashion within traditional C. Generally this means adding an extra layer of indirection here and there and designing structures to lay over each other.

You can really do lots in the way of OO situated in C this way, even though it feels like it some times, OO concepts did not spring fully formed from the mind of #include<favorite_OO_Guru.h> they really constituted many of the established best practice of the time. OO languages and systems only distilled and amplified parts of the programing zeitgeist of the day.

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I propose to use Objective-C, which is a superset of C.

While Objective-C is 30 years old, it allows to write elegant code.


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A little ooc code to add

#include <stdio.h>

struct Node {
    int somevar;

void print() {
    printf("Hello from Object-Oriented C method!");

struct Tree {
    struct Node * NIL;
    void (*FPprint)(void);  
    struct Node *root;
    struct Node NIL_t;
 } TreeA = {&TreeA.NIL_t,print};

int main()

    struct Tree TreeB;
    TreeB = TreeA;
    return 0;
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OOP is only a paradigm which place datas as more important than code in programs. OOP is not a language. So, like plain C is a simple language, OOP in plain C is simple too.

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I've been digging this for one year,

for the GObject sys is hard to use with pure c, I tried to write some nice marcos to ease the oo style with c.

#include "OOStd.h"

        char *name;
        vFn talk;
static int Animal_load(Animal *THIS,void *name){
        return 0;

static void Meow(Animal *THIS){
        printf("Meow!My name is %s!\n",THIS->name);

static int Cat_loadSt(StAnimal *THIS,void *PARAM){
        THIS->talk=(void *)Meow;
        return 0;

static void Woof(Animal *THIS){
        printf("Woof!My name is %s!\n",THIS->name);
static int Dog_loadSt(StAnimal *THIS,void *PARAM){
        THIS->talk=(void *)Woof;
        return 0;

int main(){
        Animal *animals[4000];
        StAnimal *f;
        int i=0;
                if(i%2==0) animals[i]=NEW(Dog,"Jack");
                else animals[i]=NEW(Cat,"Lily");
        return 0;

here is my project site (I dont have enough time to write en. doc,however the doc in chinese is much better)


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The answer to question is 'Yes' you can.





•Single inheritance of classes

•Multiple inheritance by interfaces and mixins (since version 1.3)

•Implementing exceptions (in pure C!)

•Virtual functions for classes

•External tool for easy class implementation

For more datails please visit http://ooc-coding.sourceforge.net/

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See http://slkpg.byethost7.com/instance.html for yet another twist on OOP in C. It emphasizes instance data for reentrancy using just native C. Multiple inheritance is done manually using function wrappers. Type safety is maintained. Here is a small sample:

typedef struct _peeker
    log_t     *log;
    symbols_t *sym;
    scanner_t  scan;            // inherited instance
    peek_t     pk;
    int        trace;

    void    (*push) ( SELF *d, symbol_t *symbol );
    short   (*peek) ( SELF *d, int level );
    short   (*get)  ( SELF *d );
    int     (*get_line_number) ( SELF *d );

} peeker_t, SlkToken;

#define push(self,a)            (*self).push(self, a)
#define peek(self,a)            (*self).peek(self, a)
#define get(self)               (*self).get(self)
#define get_line_number(self)   (*self).get_line_number(self)

(get_line_number) ( peeker_t *d )
    return  d->scan.line_number;

InitializePeeker ( peeker_t  *peeker,
                   int        trace,
                   symbols_t *symbols,
                   log_t     *log,
                   list_t    *list )
    InitializeScanner ( &peeker->scan, trace, symbols, log, list );
    peeker->log = log;
    peeker->sym = symbols;
    peeker->pk.current = peeker->pk.buffer;
    peeker->pk.count = 0;
    peeker->trace = trace;

    peeker->get_line_number = get_line_number;
    peeker->push = push;
    peeker->get = get;
    peeker->peek = peek;
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Yes, but I have never seen anyone attempt to implement any sort of polymorphism with C.

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You need to look around more :) For instance, Microsoft's Direct X has a polymorphic C interface. –  AShelly Dec 9 '08 at 19:09
Look into linux kernel implementation for example. It is very common and widely used practice in C. –  Ilya Dec 12 '08 at 3:02
also glib is polymorphic, or can be used in a way that allows polymorphism (it's like C++ you have to explicitly say which calls are virtual) –  Spudd86 Aug 31 '10 at 18:44
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#include "triangle.h"
#include "rectangle.h"
#include "polygon.h"

#include <stdio.h>

int main()
    Triangle tr1= CTriangle->new();
    Rectangle rc1= CRectangle->new();

    tr1->width= rc1->width= 3.2;
    tr1->height= rc1->height= 4.1;





/*  this is pure C, no macros preprocessing. it has innheritance, polymorphism,
data encapsulation (including private data). it not has equivalent protected 
qualifier, wich means private data it is private down the innheritance chain too.
I hope you enjoy it. So my response, based on my work and on what 
i show you here, yes, it is possible. it requieres well structured code, 
work around it, think, try and try, at least in my case. Finally you got it.
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I think that the first thing to say is that (IMHO at least) C's implementation of function pointers is REALLY hard to use. I would jump through a WHOLE lot of hoops to avoid function pointers...

that said, I think that what other people have said is pretty good. you have structures, you have modules, instead of foo->method(a,b,c), you end up with method(foo,a,b,c) If you have more than one type with a "method" method, then you can prefix it with the type, so FOO_method(foo,a,b,c), as others have said... with good use of .h files you can get private and public, etc.

Now, there are a few things that this technique WON'T give you. It won't give you private data fields. that, I think, you have to do with willpower and good coding hygiene... Also, there isn't an easy way to do inheritance with this.

Those are the easy parts at least...the rest, I think is a 90/10 kind of situation. 10% of the benefit will require 90% of the work...

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Single inheritance (without polymorphism, though) can be quite easily implemented with this technique as well. All you need to to is embed the superclass as the first member of the subclass. By the C Standard, the whole structure must necessarily be aligned with the first member, so any method designed for foo (method(foo, a, b, c)) will work when a bar pointer is passed instead (bar being a subclass of foo). This is inheritance. –  Miro Apr 29 '10 at 0:31
not really... it's used all over the place... glib is pretty much built on this idea, Linux kernel (extensively), also it's essentially the same thing that happens when you use an object oriented language, the compiler uses the same object layout that is described above (multiple inheritance complicates this slightly though, one of the superclasses must be at an offset from the object start) –  Spudd86 Aug 31 '10 at 18:49
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protected by BЈовић Jan 8 '13 at 8:06

