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

The correct answer is A: 10. 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.

What does the strspn() function do?

The correct answer is B: Spans the initial segment containing only characters from specified set. strspn(str, charset) returns length of initial segment of str containing only characters from charset. Useful for token parsing.

Which escape sequence represents a tab character in C?

The correct answer is A: \t. \t is the escape sequence for a tab character. \n is for newline, \s is invalid in C.

What does the following code snippet output? #include int main() { int x = 5; printf("%d", x++); return 0; }

The correct answer is A: 5. x++ is post-increment. The value 5 is printed first, then x is incremented to 6.

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C Programming
Dynamic Memory

C language from basics to advanced placement prep

25 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 1–10 of 25

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.1 Easy Dynamic Memory

In implementing a dynamic doubly-linked list, what additional field is required compared to singly-linked list?

A Data field

B Previous pointer

C Size field

D Head pointer

Correct Answer: B. Previous pointer

EXPLANATION

Doubly-linked list nodes require both next and previous pointers to enable bidirectional traversal unlike singly-linked lists.

Test

Q.2 Easy Dynamic Memory

If malloc() returns NULL, what should a program do?

A Ignore and continue using the pointer

B Check for NULL and handle the error appropriately

C Always typecast the return value

D Use global variables instead

Correct Answer: B. Check for NULL and handle the error appropriately

EXPLANATION

NULL return from malloc indicates allocation failure; ignoring causes dereferencing NULL which leads to crash.

Test

Q.3 Easy Dynamic Memory

In a dynamic queue implementation, if front pointer is NULL, what does it indicate?

A Queue is full

B Queue has only one element

C Queue is empty

D Memory allocation failed

Correct Answer: C. Queue is empty

EXPLANATION

In queue implementations using linked lists, NULL front pointer indicates queue is empty as there are no nodes to dequeue.

Test

Q.4 Easy Dynamic Memory

What is the primary difference between calloc() and malloc() in C?

A calloc() allocates more memory than malloc()

B calloc() initializes allocated memory to zero, malloc() does not

C malloc() is faster than calloc()

D calloc() can only allocate arrays, malloc() allocates single blocks

Correct Answer: B. calloc() initializes allocated memory to zero, malloc() does not

EXPLANATION

calloc(n, size) allocates n*size bytes and initializes all to 0, while malloc(size) allocates size bytes with garbage values.

Test

Q.5 Easy Dynamic Memory

How many bytes are allocated by malloc(sizeof(int) * 10) on a system where int is 4 bytes?

A 10 bytes

B 40 bytes

C 44 bytes

D 50 bytes

Correct Answer: B. 40 bytes

EXPLANATION

malloc allocates exactly sizeof(int) * 10 = 4 * 10 = 40 bytes. sizeof() operator returns size in bytes.

Test

Q.6 Easy Dynamic Memory

What is the result of calling free() on a NULL pointer?

A It is safe and does nothing

B It causes undefined behavior

C It frees all allocated memory

D It returns -1

Correct Answer: A. It is safe and does nothing

EXPLANATION

Calling free(NULL) is safe in C and does nothing. This is by design, allowing you to write code like free(ptr) without checking if ptr is NULL first.

Test

Q.7 Easy Dynamic Memory

What happens when malloc() fails to allocate memory?

A It returns NULL

B It throws an exception

C It allocates memory from stack

D It terminates the program

Correct Answer: A. It returns NULL

EXPLANATION

When malloc() cannot allocate the requested memory, it returns NULL. The programmer must check for NULL before using the pointer to avoid undefined behavior.

Test

Q.8 Easy Dynamic Memory

Which header file must be included to use malloc() and free() functions?

A #include

B #include

C #include

D #include

Correct Answer: A. #include

EXPLANATION

<stdlib.h> is the standard header file containing declarations for malloc(), calloc(), realloc(), and free() functions.

Test

Q.9 Easy Dynamic Memory

Which function in C is used to allocate memory dynamically at runtime?

A malloc()

B alloc()

C allocate()

D memalloc()

Correct Answer: A. malloc()

EXPLANATION

malloc() is the standard C library function for dynamic memory allocation. It takes the number of bytes to allocate as an argument and returns a pointer to the allocated memory.

Test

Q.10 Easy Dynamic Memory

Which of the following correctly allocates memory for an array of 5 integers and initializes to zero?

A int *p = malloc(5 * sizeof(int));

B int *p = calloc(5, sizeof(int));

C int *p = realloc(NULL, 5);

D int p[5] = {0};

Correct Answer: B. int *p = calloc(5, sizeof(int));

EXPLANATION

calloc(5, sizeof(int)) allocates memory for 5 integers and initializes all to zero.

Test

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