Is the C programming language object-oriented?

问题:

I was talking with a co-worker about C and C++ and he claimed that C is object-oriented, but I claimed that it was not. I know that you can do object-oriented-like things in C, but C++ is a true object-oriented language.

What are your thoughts?

Also, it triggered discussion on who decides what it means to be object-oriented and that it's tough to say what object-oriented really officially means. What are you thoughts on this?

回答1:

If by "is C object oriented?" you mean "is C designed with facilities specifically to support object oriented programming?" then, no, C is clearly not object oriented.

回答2:

You can program in an object-orientated style in more or less any language. (I think runtime polymorphism -- i.e. virtual methods -- requires a language that supports function pointers.)

Here are a couple of examples:

• A short summary of object-orientated style in C: http://www.emilmont.net/doku.php?id=c:object_oriented_c
• A comparison between the same program written in C and C++: http://www.eventhelix.com/realtimemantra/basics/object_oriented_programming_in_c.htm

回答3:

C isn't object oriented. That was the entire purpose behind the ++

As far as a definition of what it takes to be object oriented: check wikipedia.

Personally, if it supports inheritance, encapsulation, and polymorphism then your good to go. Another key here is having nice keywords like class and object tend to help...

Examples of real object oriented languages (not conclusive) are: Smalltalk, Java, c#, Python, Ruby, C++..

Also, it's possible to have extensions to provide OO features like PHP, Perl, VB (not .Net), ...

回答4:

Real programmers can write object-oriented code in ANY language.

But no, C is not an 'object-oriented' language. It has no concept of classes, objects, polymorphism, inheritance.

回答5:

The confusion may be that C can be used to implement object oriented concepts like polymorphism, encapsulation, etc. which may lead your friend to believe that C is object oriented. The problem is that to be considered an object oriented programming language, these features would need to be built into the language. Which they are not.

回答6:

1. C is not object oriented in strict sense since it doesn't have a built-in syntax supported object oriented capability like class, inheritance and so on.

But if you know the trick you can easily add object oriented capability to it simply using struct, function pointer, & self-pointer. DirectFB is such a C library written in an object oriented way. The bad thing it is more error prone since it is not governed by syntax and compile type checking. It is based on coding convention instead.

e.g.

  IDirectFB/*a typedef of a struct*/ *dfb = NULL;
  IDirectFBSurface/*another typedef of a struct*/ *primary = NULL;
  DirectFBCreate (&dfb); /*factory method to create a struct (e.g. dfb) with 
                         pointers to function and data. This struct is 
                         like an object/instance of a class in a language with build-in 
                         syntax support for object oriented capability  */
  dfb->SetCooperativeLevel/*function pointer*/ 
          (dfb/*self pointer to the object dfb*/, 
           DFSCL_FULLSCREEN);
  dsc.flags = DSDESC_CAPS;
  dsc.caps  = DSCAPS_PRIMARY | DSCAPS_FLIPPING;
  dfb->CreateSurface/*function pointer, also a factory method 
                       to create another object/instance */
          ( dfb/*self pointer to the object dfb*/, 
            &dsc, 
            &primary/*another struct work as object of another class created*/ );
  primary->GetSize/*function pointer*/ 
              (primary/*self pointer to the object primary*/, 
               &screen_width, 
               &screen_height);

2 . C++ is object oriented since it has built-in support for object oriented capability like class and inheritance. But there is argument that it is not a full or pure object oriented language since it does allow C syntax (structural programming syntax) in it. I also remember that C++ lack a few object oriented capabilities but not remember each one exactly.

回答7:

C is not an O-O language under any definition of "O-O" and "language".

It is quite easy to use C as the implementation language for a component that gives an O-O API to its clients. The X Windows system is essentially a single-inheritance O-O system when viewed from its API, but a whole mess of C when viewing its implementation.

回答8:

Unless your friend was talking about Objective C (an OO superset of C) then no, C isn't an OO language. You can implement OO concepts using C (that's what the old cfront C++ compiler did, it translated C++ into C) but that doesn't make C an OO language as it doesn't specifically offer support for standard OO techniques like polymorphism or encapsulation.

Yes, you can write software OO style in C, especially with liberal (ab-)use of macros but as someone who has seen the results of some of those attempts, I'd strongly suggest to use a better suited language.

回答9:

Real programmers can write object-oriented code in ANY language.

I have seen Object Oriented Cobol. Cobol that calls Cobol. Do you want to call these programmers "Real"?

回答10:

C is not object oriented language. C is a general-purpose, imperative language, supporting structured programming. Because C isn't object oriented therefore C++ came into existence in order to have OOPs feature and OOP is a programming language model organized around objects. A language in order to have OOPs feature needs to implement certain principles of OOPs.Few of them are Inheritance, Polymorphism, Abstraction , Encapsulation.

回答11:

No, it is not, your friend is wrong.

回答12:

Answer can be yes or no, depending on:

• if you ask "is C an object oriented language?", the answer is "no" because it do not have object oriented constructors, keywords, semantic etc...

• if you intend "can I realize OOP in C?", the answer is yes, because OOP is not only a requirement of a language, but also a way of "thinking", an approach to programming, before to touch some language or another. However the implementation of OOP in C (or any other language not natively designed to be OOP) will be surely "forced" and much hard to manage then any other OOP language, so also some limitation shall be expected.