TCS Placement: Sample Questions 439 - 440 of 502
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Question 439
Explanation
- The cyclic redundancy check (CRC) detects errors in digital data using hash function.
- Used in digital networks and storage devices such as hard disk drives.
- Invented by W. Wesley Peterson in 1961 and further developed by the CCITT (Comite Consultatif International Telegraphique et Telephonique) .
- Quite simple to implement in hardware and can be easily analyzed mathematically.
- Based on binary division
- Also called polynomial code checksum.
- Given a k-bit frame or message, the transmitter generates an n-bit sequence, known as a frame check sequence (FCS) , so that the resulting frame, consisting of (k + n) bits, is exactly divisible by some predetermined number.
- The receiver then divides the incoming frame by the same number and, if there is no remainder, assumes that there was no error.
Question 440
Question MCQ▾
Which of the following type of class allows only one object of it to be created?
Choices
Choice (4) | |
---|---|
a. | Friend Class |
b. | Virtual Class |
c. | Abstract Class |
d. | Singleton Class |
Answer
d.Explanation
- Singleton pattern is a software design pattern that restricts the instantiation of a class to one object.
- C ++ Singleton class using inheritance: In this example the base class enforces a singleton pattern.
- Note that the function calls are static calls to their global names using the scope resolution operator.
- The functions create () and instance () are defined as static functions in the class definitions.
- The concept is sometimes generalized to systems that operate more efficiently when only one object exists, or that restrict the instantiation to a certain number of objects.