PREVIOUS YEAR SOLVED PAPERS - December 2015 Paper 2
42. Which of the following statements is false?
- A
Top-down parsers are LL parsers where first L stands for left - to - right scan and second L stands for a leftmost derivation.
- B
(000)* is a regular expression that matches only strings containing an odd number of zeroes, including the empty string.
- C
Bottom-up parsers are in the LR family, where L stands for left - to - right scan and R stands for rightmost derivation.
- D
The class of context - free languages is closed under reversal. That is, if L is any context - free language, then the language LR = {wR: w∈L} is context - free.
- Option : B
- Explanation :
- Top-down parsers are LL parsers where first L stands for left - to - right scan and second L stands for a leftmost derivation.Correct
- (000)* is a regular expression that matches only strings containing an odd number of zeroes, including the empty string.Incorrect (000)* will generate ε, 000, 000000, 000000000, ........ multiples of 3 which include odd and even strings, so this is incorrect.
- Bottom-up parsers are in the LR family, where L stands for left - to - right scan and R stands for rightmost derivation.Correct
- The class of context - free languages is closed under reversal. That is, if L is any context - free language, then the language LR = {wR: w∈L} is context - free.Correct
So, option (B) is correct.
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43. System calls are usually invoked by using :
- Option : C
- Explanation :
- System calls are usually invoked by using a software interrupt.
- Polling is the process where the computer or controlling device waits for an external device to check for its readiness or state, often with low-level hardware.
- Privileged instruction is an instruction (usually in machine code) that can be executed only by the operating system in a specific mode.
- In direct jump, the target address (i.e. its relative offset value) is encoded into the jump instruction itself.
So, option (C) is correct.
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44. The __________ transfers the executable image of a C++ program from hard disk to main memory.
- Option : D
- Explanation :
- The loader transfers the executable image of a C++ program from hard disk to main memory.
- Debugger is a computer program that is used to test and debug other programs(target program).
- Compiler Compiler is a software which converts a program written in high level language (Source Language) to low level language (Object/Target/Machine Language).
- Linker takes object files, links them with each other and with any library files that you specify, and produces an executable output file.
So, option (D) is correct.
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45. In software testing, how the error, fault and failure are related to each other?
- Option : C
- Explanation : In software testing error leads to fault and fault leads to failure. rest of the option are incorrect. So, option (C) is correct.
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