Is C# a 100% Object Oriented Programming Language?

C# is NOT a pure object oriented programming language. 

Object oriented language should support:

1. Encapsulation
2. Polymorphism
3. Inheritance
4. All predefined type are objects
5. All operations performed by sending messages to objects
6. All user-defined types are objects

C# does not support point#4 & 5. 

In C#, predefined type can be struct. Example: integer > public struct Int32

So C# does not qualify as pure object oriented language.

Reference:

• http://www.jvoegele.com/software/langcomp.html
• http://stackoverflow.com/questions/3356464/is-c-sharp-a-100-object-oriented-programming-language