GATE CSE 2005 | Question: 4

Question

Which one of the following are essential features of an object-oriented programming language?

1. Abstraction and encapsulation

2. Strictly-typedness

3. Type-safe property coupled with sub-type rule

4. Polymorphism in the presence of inheritance

• A. I and II only
• B. I and IV only
• C. I, II and IV only
• D. I, III and IV only

Answer 1

B

There have been several attempts at formalizing the concepts used in object-oriented programming. The following concepts and constructs have been used as interpretations of OOP concepts:

• co algebraic data types^[44]
• abstract data types (which have existential types) allow the definition of modules but these do not support dynamic dispatch
• recursive types
• encapsulated state
• inheritance
• records are basis for understanding objects if function literals can be stored in fields       src:wikipedia

Answer 2

ans should be B

object-oriented programming language is object based programming language +abstration+inheritance.

for any OOP language ABSTRACTION and INHERITANCE are compulsory.

Answer 3

Type safety is the extent to which a programming language discourages or prevents type errors. A type error is erroneous or undesirable program behaviour caused by a discrepancy between differing data types for the program's constants, variables, and methods (functions), e.g., treating an integer (int) as a floating-point number (float).

https://stackoverflow.com/questions/805168/what-is-a-strictly-typed-language

Hence, II and III are clearly not essentials.

I & IV on the other hand form an OOPs language.

Answer : (B)

Answer 4

Ans: B it completes the three pillars of oops