Is the C programming language object-oriented?
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
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), ...