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C Programming

C language from basics to advanced placement prep

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Difficulty: All Easy Medium Hard 101–110 of 1,000

Topics in C Programming

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

Q.101 Hard Dynamic Memory

Which memory allocation technique provides better locality of reference for accessing array elements?

A Allocating each element separately with malloc

B Single malloc for contiguous array

C Using static arrays

D Allocating with calloc for zeroed memory

Correct Answer: B. Single malloc for contiguous array

EXPLANATION

Contiguous allocation places array elements next to each other in memory, improving cache hits and CPU performance through spatial locality.

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Q.102 Hard Dynamic Memory

In competitive coding, when implementing dynamic trees, which traversal is most suitable for level-order?

A Recursion with DFS

B Stack-based iteration

C Queue-based BFS using dynamic allocation

D In-order traversal

Correct Answer: C. Queue-based BFS using dynamic allocation

EXPLANATION

Level-order traversal requires BFS which uses a queue. Dynamic queue allocation handles arbitrary tree sizes efficiently.

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Q.103 Hard Dynamic Memory

What is the memory overhead when allocating 1000 integers vs 1 integer in a system with malloc metadata?

A Negligible difference

B Proportional to number of allocations

C Fixed overhead per allocation regardless of size

D Exponential with allocation count

Correct Answer: C. Fixed overhead per allocation regardless of size

EXPLANATION

Each malloc() call has fixed metadata overhead (typically 8-16 bytes). Single allocation of 1000 ints has less overhead than 1000 separate allocations.

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Q.104 Hard Dynamic Memory

For a dynamic hash table with chaining, if collision occurs, the new element should be inserted where?

A Always at the beginning of the chain

B Always at the end of the chain

C In sorted position

D Depends on implementation, typically at beginning for O(1)

Correct Answer: D. Depends on implementation, typically at beginning for O(1)

EXPLANATION

While both work, inserting at beginning provides O(1) insertion; end requires traversal. Choice depends on use case.

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Q.105 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.

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Q.106 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.

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Q.107 Medium Dynamic Memory

What is the correct way to store variable-length strings dynamically?

A char str[MAX]; gets(str);

B char *str = (char*)malloc(length+1); fgets(str, length+1, stdin);

C char *str; scanf("%s", str);

D char str[] = malloc(100);

Correct Answer: B. char *str = (char*)malloc(length+1); fgets(str, length+1, stdin);

EXPLANATION

Proper way requires dynamic allocation with malloc, adding 1 for null terminator, and using fgets for safe input.

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Q.108 Medium Dynamic Memory

In competitive programming for graph problems, if adjacency list uses dynamic arrays, what is the time complexity of adding an edge?

A O(1) amortized

B O(n)

C O(log n)

D O(n²)

Correct Answer: A. O(1) amortized

EXPLANATION

Using dynamic arrays (vectors in C++) with doubling strategy provides O(1) amortized time for appending edges.

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Q.109 Medium Dynamic Memory

Which scenario is most likely to cause a segmentation fault in dynamic memory?

A Calling malloc() multiple times

B Accessing memory beyond allocated size

C Freeing NULL pointer

D Calling realloc() on allocated memory

Correct Answer: B. Accessing memory beyond allocated size

EXPLANATION

Buffer overflow by accessing beyond allocated boundaries causes segmentation fault as it accesses invalid memory pages.

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Q.110 Medium Dynamic Memory

For implementing a dynamic circular buffer of size n, how many pointers are minimally required?

A 1 pointer

B 2 pointers

C 3 pointers

D 4 pointers

Correct Answer: B. 2 pointers

EXPLANATION

A circular buffer requires head and tail pointers minimum to track current positions in the circular structure.

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