Object Oriented Concepts Questions and Answers

Answer: C

Statements i and iii are true and ii is false. VB.NET is an object-oriented language implemented on the .NET Framework, and .NET is a free, cross-platform, open-source developer platform for building many kinds of applications. VB.NET is not a subset of Visual Basic 6.0: it is a later language built on .NET and rewritten in an object-oriented way, so VB6 programs do not run as VB.NET without changes. The options that mark ii as true or i as false are wrong.

Answer: D

Pascal is the non-.NET language among the options. C#, F# and J# are languages designed to run on the .NET platform, compiling to the common intermediate language that the .NET runtime executes. Pascal is the older language not designed for it. Pascal is a procedural language developed in the early 1970s, while the .NET family consists of languages such as C#, F# and Visual Basic that are compiled for the common language runtime.

Answer: A

The keyed answer is i, ii, iii and iv only: LISP, Java, C++ and Simula. Java, C++ and Simula are object-oriented languages, and Simula is regarded as the first. LISP is a multi-paradigm language that has object-oriented features through its object system (CLOS), and the key counts it. SQL is a database query language and C is a procedural language, so v and vi are not object-oriented. Many textbooks would leave out LISP, but the official key includes it.

Answer: A

The correct match is 1 - M, 2 - O, 3 - N, 4 - P.

• C is an imperative (procedural) language: programs are sequences of statements that change state.
• Java is object oriented: everything is organised in classes and objects.
• Lisp is the classic functional language, built on function application and lists.
• Prolog is a logic language in which a program states facts and rules as constraints, and execution searches for values that satisfy them.

The other options call Java constraint based, Lisp object oriented or Prolog functional, which mismatch these well-known paradigms.

Answer: A

The true statements are (i) and (ii).

With reference semantics, as in Java, a variable holds only a reference. Declaring it creates no object, so every object must be created explicitly, for example with new (i).

With value semantics, as for C++ objects declared as local variables, the variable is the object itself. Declaring it, passing it by value or returning it creates an object implicitly (ii).

Statements (iii) and (iv) reverse these two rules, so every option including them is wrong.

Answer: B

The answer is (ii) only: a container or collection.

In object-oriented programming, a container (also called a collection) is an object whose job is to hold a group of other objects, such as a list, set, map or vector, and to provide operations to add, remove and iterate over them.

A package groups classes, a library is a set of reusable code, and a directory list is a file-system listing. None of these is the abstraction that holds objects of a class, so options naming them are wrong.