Final Exam - Concepts of Programming Languages

Final Exam – Concepts of Programming Languages (COMP333) Time: 60 minutes 1- Which of the following identifier names is not valid in C language. (a) _Student (b) int (c) 123Student (d) Student123 2- True or False? L-value is the address of a variable, the address is what is required when the name of a variable appears in the left side of an assignment. R-value is a variable’s value, it is what it is required when the name of the variable appears in the right side of an assignment statement. (a) True (b) False 3- True or False? The type of a variable determines the range of values the variable can store and the set of operations that are defined for values of the type. (a) True (b) False 4-True or False? Case-sensitive violates writability, because names that look very similar in fact denote different entities. (a) True (b) False 5-Which category of C++ reference variables are always aliases? (a) Two pointer variables are aliases when they point to the same memory location (b) When a C++ pointer is set to point at a named variable, the pointer, when dereferenced, and the variable’s name are aliases (c) All of the mentioned 6- Assume the following JavaScript program was interpreted using dynamicscoping rules, what value of x is displayed in function sub1? var x; function sub1() { document.write (“x = ” + x + “
”); } function sub2() { var x; x = 10; sub1(); } x = 5; sub2(); (a) (b) (c) X=5 X=10 Determined randomly, 5 or 10 7-True or False? (a) Binding is an association such as between an attribute and an entity, or between an operation and a symbol. Binding time is the time at which a binding takes place. (b) Static binding: if it first occurs before run time and remains unchanged throughout program execution. (c) Dynamic binding: if it first occurs during execution or can change during execution of the program. (d) All of the mentioned 8- Which following items are true? (a) The only advantage of dynamic scoping is writability. It is more convenient and it provides more flexibility than static scoping. (b) Dynamics scoping also makes program difficult to read because the calling sequence of subprograms must be known to determine the meaning of references to nonlocal variables. (c) Accessing to nonlocal variables in dynamic scoping takes far longer than accesses to nonlocal variables when static scoping is used (d) All of the mentioned 9- Which following items are true? (a) Heap memory management is used when explicit memory allocation is allowed. (b) Static memory management is used when explicit memory allocation is allowed (c) Stack memory management is used when explicit memory allocation is allowed (d) None of above is correct 10- If the language permits recursion (a) Static allocation of memory is sufficient (b) Dynamic memory allocation and deallocation operations are needed at runtime (c) Can't be implemented using a stack (d) None of above is correct 11-What level of program concurrency is best supported by MIMD computers? (a) Unit-level concurrency is best supported by MIMD computer (b) Machine instruction level concurrency is best supported by MIMD computers. (c) Program level concurrency is best supported by MIMD computers (d) High- level language statement concurrency is best supported by MIMD computers 12- Which following items are true? (a) Heavy weight task executes in its own address space. (b) Lightweight task all run in the same address space. (c) Both of above are correct (d) None of above is correct 13- True or False? Task descriptor is a data structure that stores all of the relevant information about the execution state of a task. (a) True (b) False 14- True or False? Guard is a linguistic device that allows the guarded code to be executed only when a specified condition is true. (a) True (b) False 15- True or False? The use of DISTRIBUTE and ALIGN specification of HPC is to provide information to the compiler on machines that do not share memory, that is, each processor has its own memory (a) True (b) False 16- True or False? Monitor can provide competition synchronization without semaphores by transferring responsibility for synchronization to the run-time system. (a) True (b) False 17- True or False? A binary semaphore is a semaphore that requires only a binary-valued counter. A counting semaphore is a synchronization object that can have an arbitrarily large number of states. (a) True (b) False 18- In what three common languages can monitors be implemented? (a) Java, Ada, and C++ (b) Java, Ruby, and C++ (c) Ada, java, and C# (d)Java, Ada, JavaScript 19- What does the Java yield method do? (a) The Java yield method immediately put the thread in the task-ready queue. Making it ready to run. (b) The Java yield method blocks the thread. (c) The Java yield method terminated the thread. 20- True or False? What is the difference between physical and logical concurrency? (a)Physical concurrency is several program units from the same program that literally execute simultaneously. (b)Logical concurrency is multiple processors providing actual concurrency, when in fact the actual execution of programs is taking place in interleaved fashion on a single processor. (a) True (b) False 21- True or False? What is left factoring? Left factoring is the action taken when a grammar leads backtracking while marking pars syntax tree (a) True (b) False 22- Which following items are true? (a) Top-down parsers: Parsers build the tree from the root downward to the leaves. (b) Bottom-up Parsers: Build the tree from the leaves upward to the root (c) Both of above are correct (d) None of above is correct 23- True or False? A recursive-descent parser is coded directly from the BNF description of the syntax of a language. An alternative is to use a parsing table rather than code. (a) True (b) False 24- Which following items are true? (a) LL Parser: The first L in LL specifies a left-to-right scan of the input; the second L specifies that a leftmost derivation is generated (b) LR Parser specifies a left-to-right scan and the R specifies that a rightmost derivation is generated (c) LR parsers can be built for all programming languages. They can detect syntax errors as soon as possible in a left-to-right scan. (d) All above are correct 25- True or False? Given the following grammar and the right sentential form as the input, is the following parse tree correct? S → aAb | bBa A → ab | aAb B → aB | b Input: aaAbb (a) True (b) False 26- Why classes are known as abstract data types (ADT)? (a) Because classes are user-defined data types (b) Because it supports the theory of hierarchical classification (c) Because it allows dynamic binding (d) Because it uses the concept of data abstraction 27- Which is not true about the object-oriented approach? (a) Emphasis is on data rather than procedure (b) Data is hidden and cannot be accessed by external functions (c) Objects communicate through functions (d) It supports abstract data but not the class 28- True or False? The purpose of the let in functional languages introduces a new variable scope, and allows you to bind variables to values for that scope (a) True (b) False 29-Which access specifier makes the class member accessible outside the class but can be accessed by any subclass of that class? (a) Private (b) Public (c) Protected 30- Which one of the following is the main benefit of single inheritance? (a) Presence of ambiguity (b) Absence of ambiguity (c) Provides modularity (d) Does not provide modularity 31- When we override an inherited method in a subclass, we can _____ its access but not ____ it? (a) Increase, decrease (b) Decrease, increase (c) None of the mentioned. 32- _____ is associated with polymorphism and inheritance. (a) Message parsing (b) Abstraction (c) Dynamic Binding (d) Encapsulation 33- What are the types of memory allocated in memory in java? (a) Heap memory (b) Stack memory (c) Both A and B (d) None of these 34- In java, recursion is ___. (a) Method (b) A process allowing methods to call itself (c) The process to call methods (d) None of these 35- Encapsulation is ___. (a) Wrapping up of data and related functions into a single entity (b) Creating special methods (c) Creating special data structure (d) All of these 36- What is a deadlock in Java? (a) State when all processes have complete working and are dead (b) State when threads are in hold state forever (c) State when threads are not ready (d) All of these 37- Which keyword is used to inherit classes in Java? (a) extends (b) inheritance (c) isChild (d) None of these 38- What is polymorphism in Java? (a) Performing a single task in multiple ways (b) Performing multiple tasks using multiple methods (c) Creating a new class for each task (d) All of these 39- True or False? The functioning of a process, and the output it produces, must be independent of the speed at which its execution is carried out relative to the speed of other concurrent processes. (a) True (b) False 40- Which of these is a property of threads in Java? (a) Multiple threads can be executed concurrently (b) Has its own priority (c) Both A. and B. (d) None of these