Can you write object-oriented code in C? [closed]

Question

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

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See also Stack Overflow question Object-orientation in C.

Answer 1

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.

Answer 2

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).

Answer 3

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

Answer 4

Yes, but I have never seen anyone attempt to implement any sort of polymorphism with C.

Answer 5

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.

Answer 6

A little OOC code to add:

#include <stdio.h>

struct Node {
    int somevar;
};

void print() {
    printf("Hello from an 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;
    TreeB.FPprint();
    return 0;
}