Arrays Questions and Answers

Q: A one dimensional array A has indices 1....75. Each element is a string and takes up three memory words. The array is stored at location 1120 decimal. The starting address of A[49] is

Correct answer: 1264Indices start at 1 here, not 0, so \(A[49]\) is the 49th element and 48 elements precede it. Each takes 3 words:\[ 1120 + 3 \times (49 - 1) = 1120 + 144 = 1264 \]Forgetting the 1-based start gives 1267, which is the distractor.

Q: In C, if you pass an array as an argument to a function, what actually gets passed?

Correct answer: Base address of the arrayAn array argument decays to a pointer to its first element, so what the function receives is the base address, not a copy of the elements. This is why passing a large array costs nothing extra, why the function can modify the caller’s data, and why sizeof inside the function returns the size of a pointer rather than of the array.

Q: Under which of the following conditions, the size of an one-dimensional array need not be specified?

Correct answer: All of the aboveAll three permit the size to be left out. With an initialiser the compiler counts the values. In a declaration such as extern int a[]; the size comes from the definition elsewhere. And as a formal parameter the array is adjusted to a pointer, so no bound is needed - nor at the call site, where the name is passed alone.

Q: Predict the output of the code below, if the array begins at address 65472 and each integer occupies 2 bytes. #include <stdio.h> int main() { int a[3][4] = {1, 2, 3, 4, 4, 3, 2, 1, 7, 8, 9, 0}; printf("%u, %u\n", a+1, &a+1); return 0; }

Correct answer: 65480, 65496a is a 3×4 array of 2-byte ints. a decays to a pointer to its first row, so a+1 steps over 4 ints:\[ 65472 + 4 \times 2 = 65480 \]&a is a pointer to the whole array, so &a+1 steps over all 12:\[ 65472 + 12 \times 2 = 65496 \]

Q: Choose the correct statements

Correct answer: Both (a) and (b)(a) is true: C really has only one-dimensional arrays - int a[3][4] is an array of 3 objects, each of type int[4]. (b) says the same thing from the other side: an element may itself be an array. The third statement is false; elements are always contiguous, which is exactly what makes subscripting work.

Q: If S is an array of 80 characters, then the value assigned to S through the statement scanf("%s",S) with input 12345 would be

Correct answer: "12345"%s reads a whitespace-delimited sequence of characters and stores them followed by a null, without interpreting them. The digits 12345 are just five characters here, so S holds the string "12345". Note that S is passed without &, because an array name already yields its base address.

Q: Consider a two dimensional array A[20][10]. Assume 4 words per memory cell, the base address of array A is 100, elements are stored in row-major order and first element is A[0][0]. What is the address of A[11][5] ?

Correct answer: 560Row-major, so \(A[i][j]\) sits at \(\text{base} + w\,(i \times \text{columns} + j)\), with 10 columns and \(w = 4\):\[ 100 + 4\,(11 \times 10 + 5) = 100 + 4 \times 115 = 560 \]

Q: C does no automatic array bound checking. This is best described as

Correct answer: C's shortcomingC performs no bounds check, so an out-of-range subscript quietly reads or writes memory belonging to something else. It is generally counted a shortcoming - the source of buffer overflows and of many hard-to-find bugs. The omission was deliberate, since it keeps array access as cheap as raw address arithmetic, but later languages reinstated the check for good reason.

Q: Choose the correct statements

Correct answer: All of theseAll three statements are true. An array’s size is fixed when it is created and cannot be changed. The values of its elements may be reassigned as often as you like. And because indexing starts at 0, the nth element is reached as students[n-1].

11.

A one dimensional array A has indices 1....75. Each element is a string and takes up three memory words. The array is stored at location 1120 decimal. The starting address of A[49] is

A.1264
B.1164
C.1167
D.1267

Answer: A

Correct answer: 1264

Indices start at 1 here, not 0, so \(A[49]\) is the 49th element and 48 elements precede it. Each takes 3 words:

\[ 1120 + 3 \times (49 - 1) = 1120 + 144 = 1264 \]

Forgetting the 1-based start gives 1267, which is the distractor.

Discuss in Forum

12.

In C, if you pass an array as an argument to a function, what actually gets passed?

A.Value of elements in array
B.First element of the array
C.Base address of the array
D.Address of the last element of array

Answer: C

Correct answer: Base address of the array

An array argument decays to a pointer to its first element, so what the function receives is the base address, not a copy of the elements. This is why passing a large array costs nothing extra, why the function can modify the caller’s data, and why sizeof inside the function returns the size of a pointer rather than of the array.

Discuss in Forum

13.

Under which of the following conditions, the size of an one-dimensional array need not be specified?

A.when initialization is a part of definition
B.when it is a declaration
C.when it is a formal parameter and an actual argument
D.All of the above

Answer: D

Correct answer: All of the above

All three permit the size to be left out. With an initialiser the compiler counts the values. In a declaration such as extern int a[]; the size comes from the definition elsewhere. And as a formal parameter the array is adjusted to a pointer, so no bound is needed - nor at the call site, where the name is passed alone.

Discuss in Forum

14.

Predict the output of the code below, if the array begins at address 65472 and each integer occupies 2 bytes.

#include <stdio.h>

int main()
{
    int a[3][4] = {1, 2, 3, 4, 4, 3, 2, 1, 7, 8, 9, 0};
    printf("%u, %u\n", a+1, &a+1);
    return 0;
}

A.65430, 43569
B.65239, 64763
C.65480, 65496
D.61123, 74123

Answer: C

Correct answer: 65480, 65496

a is a 3×4 array of 2-byte ints. a decays to a pointer to its first row, so a+1 steps over 4 ints:

\[ 65472 + 4 \times 2 = 65480 \]

&a is a pointer to the whole array, so &a+1 steps over all 12:

\[ 65472 + 12 \times 2 = 65496 \]

Discuss in Forum

15.

Choose the correct statements

A.Strictly speaking C supports 1-dimensional arrays only
B.An array element may be an array by itself
C.Array elements need not occupy contiguous memory locations
D.Both (a) and (b)

Answer: D

Correct answer: Both (a) and (b)

(a) is true: C really has only one-dimensional arrays - int a[3][4] is an array of 3 objects, each of type int[4]. (b) says the same thing from the other side: an element may itself be an array. The third statement is false; elements are always contiguous, which is exactly what makes subscripting work.

Discuss in Forum

16.

If S is an array of 80 characters, then the value assigned to S through the statement scanf("%s",S) with input 12345 would be

A."12345"
B.nothing since 12345 is an integer
C.S is an illegal name for string
D.%s cannot be used for reading in values of S

Answer: A

Correct answer: "12345"

%s reads a whitespace-delimited sequence of characters and stores them followed by a null, without interpreting them. The digits 12345 are just five characters here, so S holds the string "12345". Note that S is passed without &, because an array name already yields its base address.

Discuss in Forum

17.

Consider a two dimensional array A[20][10]. Assume 4 words per memory cell, the base address of array A is 100, elements are stored in row-major order and first element is A[0][0]. What is the address of A[11][5] ?

A.560
B.460
C.570
D.575

Answer: A

Correct answer: 560

Row-major, so \(A[i][j]\) sits at \(\text{base} + w\,(i \times \text{columns} + j)\), with 10 columns and \(w = 4\):

\[ 100 + 4\,(11 \times 10 + 5) = 100 + 4 \times 115 = 560 \]

Discuss in Forum

18.

C does no automatic array bound checking. This is best described as

A.true
B.false
C.C's asset
D.C's shortcoming

Answer: D

Correct answer: C's shortcoming

C performs no bounds check, so an out-of-range subscript quietly reads or writes memory belonging to something else. It is generally counted a shortcoming - the source of buffer overflows and of many hard-to-find bugs. The omission was deliberate, since it keeps array access as cheap as raw address arithmetic, but later languages reinstated the check for good reason.

Discuss in Forum

19.

Choose the statement that best defines an array

A.It is a collection of items that share a common name
B.It is a collection of items that share a common name and occupy consecutive memory location
C.It is a collection of items of the same type and storage class that share a common name and occupy consecutive memory locations
D.None of the above

Answer: C

Correct answer: It is a collection of items of the same type and storage class that share a common name and occupy consecutive memory locations

The fullest definition is the right one. All three properties matter: one type and storage class, so every element is the same size; one name with an index; and consecutive memory, which is what lets a[i] be computed as an offset from the base. Drop any of the three and the index arithmetic no longer works.

Discuss in Forum

20.

Choose the correct statements

A.An array size cannot be changed once it is created.
B.Array element value can be changed any number of times
C.To access Nth element of an array students, use students[n-1] as the starting index is 0.
D.All of these

Answer: A

Correct answer: All of these

All three statements are true. An array’s size is fixed when it is created and cannot be changed. The values of its elements may be reassigned as often as you like. And because indexing starts at 0, the nth element is reached as students[n-1].

Discuss in Forum

Loading…

Topics

Other Subjects

Tags: Arrays Questions and Answers || Arrays MCQ Questions and Answers || Arrays GK Questions and Answers || Arrays GK MCQ Questions || Arrays Multiple Choice Questions and Answers || Arrays GK || GK on Arrays || C Programming Questions and Answers || C Programming MCQ Questions and Answers || C Programming GK Questions and Answers || GK on C Programming

Arrays Questions and Answers

Topics

Other Subjects

About Us

Stay informed about all important Dates & Notifications