Top 10 Technical Interview & Aptitude Questions

If you’re preparing for technical interviews, these fundamental questions will help you strengthen your concepts and boost your confidence. Understanding these topics will not only help you crack interviews but also enhance your problem-solving skills. Let’s dive in!

1. What is the difference between an array and a list?

Answer:

• An array is a collection of homogeneous elements (same data type), whereas a list can contain heterogeneous elements (different data types).
• Arrays use static and contiguous memory allocation, whereas lists use dynamic and non-contiguous memory allocation.
• Arrays allow direct access to elements, while lists require sequential access.

🔹 Visual: Diagram comparing memory allocation of arrays vs lists.

2. What are the differences between structures and arrays?

Answer:

• Arrays store multiple elements of the same data type, whereas structures can store different data types in a single entity.
• Arrays have a fixed size, while structures allow multiple data types grouped together.

🔹 Visual: Table comparing arrays vs structures.

3. What is a data structure?

Answer: A data structure is a way of organizing and managing data efficiently. It helps in the easy retrieval, manipulation, and storage of data. Examples include arrays, linked lists, stacks, and trees.

4. Where are data structures extensively applied?

Answer: Data structures are widely used in:

• Compiler Design
• Operating Systems
• Database Management Systems
• Statistical Analysis Packages
• Graphics and Multimedia Processing

5. What are the advantages of inheritance?

Answer:

• Encourages code reusability, reducing development time.
• Promotes debugged and high-quality software reuse.
• Helps in achieving a hierarchical class structure.

6. What are the advantages of a macro over a function?

Answer:

• Macros expand at compile-time, avoiding function call overhead.
• They allow preprocessor-based substitutions, making them faster than functions.

🔹 Visual: Example of macro vs function execution.

7. What is a command-line argument?

Answer: A command-line argument is an input passed to a program when it starts executing. The main() function in C/C++ supports command-line arguments:

• argc: Argument count
• argv: Argument vector (array of strings)
• envp: Environment vector

8. What are the four basics of Object-Oriented Programming (OOP)?

Answer:

• Abstraction: Hiding implementation details.
• Encapsulation: Bundling data and methods together.
• Inheritance: Acquiring properties of another class.
• Polymorphism: Using a single interface for multiple functionalities.

🔹 Visual: A simple UML diagram explaining OOP concepts.

9. How to check whether a linked list is circular?

Answer: Use two pointers to traverse the linked list:

void checkCircular(struct Node *head) {
    struct Node *slow = head, *fast = head;
    while (fast && fast->next) {
        slow = slow->next;
        fast = fast->next->next;
        if (slow == fast) {
            printf("The list is circular\n");
            return;
        }
    }
    printf("The list is not circular\n");
}

10. Write a program to swap two numbers without using a temporary variable.

Answer:

#include <stdio.h>
void swap(int *x, int *y) {
    *x = *x + *y;
    *y = *x - *y;
    *x = *x - *y;
}
int main() {
    int a = 5, b = 10;
    swap(&a, &b);
    printf("After Swap: a = %d, b = %d\n", a, b);
    return 0;
}

Conclusion

Mastering these fundamental questions will give you an edge in technical interviews. Make sure you understand the concepts rather than memorizing them. Practice coding regularly, and you’ll see significant improvement!