What is the time complexity of accessing an element at index 5 in an array?

The correct answer is A: O(1) - Constant time. Array access by index is O(1) because arrays use contiguous memory allocation, allowing direct access via base address + offset calculation.

A program needs to update specific bytes in the middle of a file without affecting other data. Which approach is most suitable?

The correct answer is A: Use fseek() to position pointer, then fwrite() the new data. Using fseek() with r+ or w+ mode allows direct access to specific file positions. This is efficient for small modifications without rewriting the entire file.

Which of the following macro definitions will correctly compute the absolute value? #define ABS(x) ((x)

The correct answer is A: Correct - uses ternary operator with proper precedence. The macro correctly uses the ternary operator with proper parenthesization. Each use of x is wrapped in parentheses to prevent precedence issues. This is a well-formed macro for computing absolute value.

What is the output of: int add(int a, int b) { int result = a + b; return result; } If called as add(5, 3)?

The correct answer is A: 8. The function simply adds two integers and returns their sum, which is 5 + 3 = 8.

In a structure with flexible array members, which statement is INCORRECT? struct FlexArray { int len; int arr[]; };

The correct answer is B: Structure can be allocated on stack directly. Flexible array members require dynamic allocation; the structure itself cannot be allocated on the stack with a defined size for the array.

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C Programming

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291 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 141–150 of 291

Topics in C Programming

All Basics & Syntax 86 Data Types & Variables 97 Control Flow 100 Functions 99 Arrays & Strings 100 Pointers 99 Structures & Unions 100 File Handling 100 Dynamic Memory 98 Preprocessor 99

Q.141 Easy Pointers

What will be the size of a pointer variable on a 64-bit system?

A 2 bytes

B 4 bytes

C 8 bytes

D 16 bytes

Correct Answer: C. 8 bytes

EXPLANATION

On a 64-bit system, a pointer is 8 bytes (64 bits) regardless of the data type it points to.

Test

Q.142 Easy Pointers

Which operator is used to get the address of a variable in C?

A *

B &

C ->

D .

Correct Answer: B. &

EXPLANATION

The & operator (address-of operator) returns the memory address of a variable.

Test

Q.143 Easy Arrays & Strings

Consider the following code:

char str[] = "HELLO";
int len = 0;
while(str[len] != '\0') {
len++;
}
printf("%d", len);

What will be the output?

A 5

B 6

C 4

D Undefined behavior

Correct Answer: A. 5

EXPLANATION

The string "HELLO" has 5 characters. The while loop counts characters until it encounters the null terminator '\0'. The output will be 5. The null terminator is not counted in the length.

Test

Q.144 Easy Arrays & Strings

What will be the size in bytes of int arr[5] on a 32-bit system?

A 5 bytes

B 10 bytes

C 20 bytes

D Depends on compiler

Correct Answer: C. 20 bytes

EXPLANATION

On 32-bit systems, int is typically 4 bytes. 5 elements × 4 bytes = 20 bytes total.

Test

Q.145 Easy Arrays & Strings

What is the output of: int arr[] = {10, 20, 30}; printf("%d", *(arr+1));?

A 10

B 20

C 30

D Garbage value

Correct Answer: B. 20

EXPLANATION

arr+1 points to second element (arr[1]). Dereferencing gives value 20.

Test

Q.146 Easy Arrays & Strings

What is the correct way to declare and initialize a string in C?

A char str = "Hello";

B char *str = "Hello"; OR char str[] = "Hello";

C String str = "Hello";

D char str[10] = {"Hello"};

Correct Answer: B. char *str = "Hello"; OR char str[] = "Hello";

EXPLANATION

Option B shows two valid ways: pointer to string literal or character array. Option A is wrong (single char), C is wrong (no String type in C).

Test

Q.147 Easy Arrays & Strings

How many elements can be stored in a 2D array declared as int matrix[4][5]?

A 4 elements

B 5 elements

C 9 elements

D 20 elements

Correct Answer: D. 20 elements

EXPLANATION

A 2D array with dimensions [4][5] contains 4 × 5 = 20 elements total.

Test

Q.148 Easy Arrays & Strings

In the declaration char *str[5], what does the array represent?

A Array of 5 character pointers

B Pointer to array of 5 characters

C Single pointer to a string of 5 characters

D 5 pointers to individual characters

Correct Answer: A. Array of 5 character pointers

EXPLANATION

The syntax char *str[5] declares an array of 5 pointers, each pointing to a character (or string). The brackets bind tighter than asterisk.

Test

Q.149 Easy Arrays & Strings

Which of the following correctly initializes a 2D array of integers?

A int arr[3][3] = {1,2,3,4,5,6,7,8,9};

B int arr[][] = {1,2,3,4,5,6};

C int arr[3][] = {{1,2},{3,4},{5,6}};

D int arr[3][3];

Correct Answer: A. int arr[3][3] = {1,2,3,4,5,6,7,8,9};

EXPLANATION

Option A is valid - 2D arrays can be initialized with all elements in a single brace. Options B and C are invalid as at least one dimension must be specified.

Test

Q.150 Easy Arrays & Strings

What is the size of the string 'Hello' when stored in a character array with null terminator?

A 5 bytes

B 6 bytes

C 7 bytes

D Depends on compiler

Correct Answer: B. 6 bytes

EXPLANATION

'Hello' has 5 characters plus 1 null terminator (\0), making total 6 bytes.

Test

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