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 will be the behavior of this code? struct s { int a; }; struct s obj = {5}; struct s *ptr = &obj; ptr->a = 10; printf("%d", obj.a);

The correct answer is B: 10. ptr points to obj, so ptr->a = 10 modifies obj.a to 10. The printf outputs the modified value 10.

What happens when you initialize a structure variable without assigning values?

The correct answer is B: Members contain garbage values. Uninitialized local structure variables contain garbage values. Global structures are automatically initialized to zero.

A variable declared with 'register' storage class suggests to the compiler to store it in:

The correct answer is B: CPU registers. register is a hint to compiler to store variable in CPU register for faster access. Compiler may ignore this if registers unavailable.

Consider the code: int *p; int arr[5] = {10, 20, 30, 40, 50}; p = arr; What is *(p+2)?

The correct answer is B: 30. p points to arr[0]. p+2 points to arr[2], which contains 30.

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C Programming
Arrays & Strings

C language from basics to advanced placement prep

49 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–40 of 49

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.31 Medium Arrays & Strings

What will be the output?
char arr[] = "ABC";
printf("%d", sizeof(arr));

A 3

B 4

C Depends on compiler

D Runtime error

Correct Answer: B. 4

EXPLANATION

sizeof includes the null terminator. "ABC" has 4 bytes (A, B, C, \0).

Test

Q.32 Medium Arrays & Strings

Which function is used to find the first occurrence of a character in a string?

A strstr()

B strchr()

C strtok()

D strrchr()

Correct Answer: B. strchr()

EXPLANATION

strchr() finds the first occurrence of a character. strrchr() finds the last occurrence. strstr() finds substrings.

Test

Q.33 Medium Arrays & Strings

What is the time complexity of inserting an element at the beginning of an unsorted array?

A O(1) - Constant time

B O(n) - Linear time (need to shift all elements)

C O(log n) - Logarithmic time

D O(n²) - Quadratic time

Correct Answer: B. O(n) - Linear time (need to shift all elements)

EXPLANATION

Inserting at the beginning requires shifting all n elements one position right, making it O(n). Insertion at the end is O(1) if space exists.

Test

Q.34 Medium Arrays & Strings

What happens when you try to modify a string literal in C?

A The modification succeeds and permanent change occurs

B Compile-time error is generated

C Runtime error (segmentation fault or undefined behavior)

D The string is automatically copied before modification

Correct Answer: C. Runtime error (segmentation fault or undefined behavior)

EXPLANATION

String literals are stored in read-only memory. Attempting modification causes undefined behavior (often segmentation fault). This is why char *str = "text"; str[0]='T'; is dangerous.

Test

Q.35 Medium Arrays & Strings

Which string function modifies the original string in-place?

A strtok()

B strlen()

C strcpy()

D Both A and C

Correct Answer: D. Both A and C

EXPLANATION

Both strtok() (modifies by replacing delimiters with '\0') and strcpy() (copies and overwrites destination) modify strings in-place.

Test

Q.36 Medium Arrays & Strings

What is the output of sizeof(arr)/sizeof(arr[0]) when arr is declared as int arr[10]?

A 10

B 40

C 4

D Depends on system architecture

Correct Answer: A. 10

EXPLANATION

This expression calculates array length. sizeof(arr) gives total bytes (40 on 32-bit system), sizeof(arr[0]) gives bytes per element (4), so 40/4=10.

Test

Q.37 Medium Arrays & Strings

In a 2D array int matrix[4][5], which statement about memory layout is true?

A Elements are stored in row-major order (row by row)

B Elements are stored in column-major order (column by column)

C Elements are randomly scattered in memory

D Memory layout depends on the compiler version

Correct Answer: A. Elements are stored in row-major order (row by row)

EXPLANATION

C uses row-major order for 2D arrays. matrix[0][0], matrix[0][1]...matrix[0][4], matrix[1][0]... are stored sequentially in memory.

Test

Q.38 Medium Arrays & Strings

If str = "Hello", what is the value of str[5]?

A '\0' (null character)

B 'o'

C Garbage value

D Error - index out of bounds

Correct Answer: A. '\0' (null character)

EXPLANATION

"Hello" has 5 characters, so valid indices are 0-4. Index 5 contains the null terminator '\0' that marks the end of the string.

Test

Q.39 Medium Arrays & Strings

What is the relationship between array name and pointer in C?

A Array name decays to a pointer to its first element in most contexts

B Array name is exactly equivalent to a pointer variable

C Array names and pointers have no relationship

D Array name is a constant pointer that can be modified

Correct Answer: A. Array name decays to a pointer to its first element in most contexts

EXPLANATION

Array names decay to pointers to the first element in expressions, but they are not truly pointer variables. The array name cannot be reassigned.

Test

Q.40 Medium Arrays & Strings

Which of the following correctly declares and initializes a 2D array?

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

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

C Both A and B are correct

D Neither A nor B is valid

Correct Answer: C. Both A and B are correct

EXPLANATION

Both syntax forms are valid in C. Elements can be provided in nested braces or as a linear list, and they fill row by row.

Test

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