Computer Knowledge

Programming Fundamentals

2,611 Questions

Programming fundamentals form the core logic of software development and computer science. This includes variable declarations, pointer assignments, loop iterations, and exception handling. These technical topics are regularly tested in computer knowledge and IT officer competitive examinations.

Variables and arraysPointer assignmentsLoop iterationsException handling blocksCompile time errorsFunction references

Programming Fundamentals Questions

Multiple choice

Which of the following problems are decidable? 1) Does a given program ever produce an output? 2) If L is context-free language, then, is L also context-free? 3) If L is regular language, then, is L also regular? 4) If L is recursive language, then, is L also recursive?

  1. 1,2,3,4

  2. 1, 2

  3. 2, 3, 4

  4. 3, 4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

CFL’s are not closed under complementation. Regular and recursive languages are closed under complementation.

Multiple choice

Fetch_And_Add (X, i) is an atomic Read-Modify-Write instruction that reads the value of memory location X, increments it by the value i, and returns the old value of X. It is used in the pseudocode shown below to implement a busy-wait lock. L is an unsigned integer shared variable initialized to 0. The value of 0 corresponds to lock being available, while any non-zero value corresponds to the lock being not available. AcquireLock(L){ While (Fetch_And_Add(L,1)) L = 1; } Release Lock (L){ L = 0; } This implementation

  1. fails as L can overflow

  2. fails as L can take on a non-zero value when the lock is actually available

  3. works correctly but may starve some processes

  4. works correctly without starvation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Multiple choice

Direction: The following code segment is executed on a processor which allows only register operands in its instructions. Each instruction can have almost two source operands and one destination operand. Assume that all variables are dead after this code segment. c = a + b; d = c * a; e = c + a; x = c * c; if (x > a) { y = a* a; } else { d = d * d; e = e * e; }

Suppose the instruction set architecture of the processor has only two registers. The only allowed compiler optimisation is code motion, which moves statements from one place to another while preserving correctness. What is the minimum number of spills to memory in the compiled code?

  1. 0

  2. 1

  3. 2

  4. 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the above code, total number of spills to memory is 2.

Multiple choice

Suppose a processor does not have any stack pointer register. Which of the following statements is true?

  1. It cannot have subroutine call instruction.

  2. It can have subroutine call instruction, but no nested subroutine calls.

  3. Nested subroutine calls are possible, but interrupts are not.

  4. All sequences of subroutine calls and also interrupts are possible.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Stack pointer register holds the address of top of stack, which is the location of memory at which the CPU should resume its execution after servicing some interrupt or subroutine call. So if SP register not available then no subroutine call instructions are possible.

Multiple choice

In the C language

  1. At most one activation record exists between the current activation record and the activation record for the main.

  2. The number of activation records between the current activation record and the activation record for the main depends on the actual function calling sequence.

  3. The visibility of global variables depends on the actual function calling sequence.

  4. Recursion requires the activation record for the recursive function to be saved on a different stack before the recursive fraction can be called.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Activation record is the contiguous memory locations where the data needed by the program is kept so at most one activation record exist between current activation record & the record for the main.

Multiple choice

Assume the following C variable declaration

int * A[10], B[10][10]; of the following expressions

I. A[2]
II. A[2][3]
III. B[1] IV. B[2][3]

Which will not give compile-time errors if used as left hand sides of assignment statements in a C program?

  1. I,II, and IV only

  2. II, III, and IV only

  3. II and IV only

  4. IV only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation 
int main(){
    int *A[10], B[10][10];
    int c[] = {12, 11, 13, 14};

   A[2] = C;

   A[2][3] = 15;

   B[2][3] = 15;

   printf("%d %d', A[2][0], A[2][3]);
   getchar();
}
Multiple choice

Consider the following C function void swap (int a, int b) { int temp; temp =a; a =b; b =temp; } In the order to exchange the values of two variables x and y .

  1. call swap (x,y)

  2. call swap (&x,&y)

  3. swap (x,y) cannot be used as it does not return any value

  4. swap (x,y) cannot be used as the parameters are passed by value
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Here the function takes the arguments by value.

$\rightarrow$       Option (A) sends parameter by value but only the local variable a & b will be exchanged but not the actual variables x & y so incorrect. $\rightarrow$ Option (B) is incorrect sending address of x & y . $\rightarrow$ Option (C) swap (x,y) is usable there is no need to return. $\rightarrow$ Option (D) is the opposite statement of option (A), it says that the values are passed by value so won't swap so the option is correct.