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HCL tech most 50+ Asked Technical Equations in interview

HCL Hiring Process

HCL Technologies recruits freshers through a two-step process:

Round 1:

  • Online Written Test

Round 2:

  • Technical Interview
  • HR Interview

Profiles Offered

HCL primarily hires freshers in India under a single profile:

  • Graduate Engineer Trainee (GET) – ₹4.3 LPA

Modes of Hiring:

  • On-Campus
  • Off-Campus

HCL was established in 1976 as one of India’s earliest IT startups. The company played a key role in modern computing, including launching personal computers based on 8-bit microprocessors in 1978.


Salary & Benefits

  • Approximate monthly in-hand: ₹30,000 (after deductions like PF, professional tax, gratuity, etc.)
  • Annual increments: 15–25% depending on performance and appraisal
  • Location: Noida
  • Other Benefits:
    • Relocation allowance & accommodation (15 days)
    • Fitness reimbursement
    • Flexi points for insurance
    • OPD expenses (covered under insurance)
    • Executive health check-ups

Note: Reimbursement-based benefits may lapse if not used.


HCL Hiring Process (Detailed)

1. Online Assessment

  • Eliminates around 75% of candidates
  • Called the Cognitive Test in on-campus drives
  • Sections:
    • Quantitative / Numerical Ability – 15 Qs
    • Logical Reasoning – 15 Qs
    • Verbal Ability – 15 Qs
    • Computer Fundamentals – 30 Qs
  • Total time: 75 minutes
  • Difficulty: Medium (often considered tough by students)

2. Technical Interview

  • Eliminates around 95% of candidates
  • Duration: 1–1.5 hours
  • Focus areas:
    A. Programming Languages: Basics of C/C++, Java, or Python to assess continuation eligibility
    B. DBMS / SQL: 10 mins for queries, concepts, and database fundamentals
    C. DSA & Coding: 45–50 mins for data structures, algorithms, competitive coding, and code optimization (time & space complexity)
  • Typically conducted by industry professionals with 3–5 years of experience

3. HR Interview

  • Eliminates around 99% of candidates up to this round
  • Focuses on:
    • Communication skills
    • Cultural fit with HCL
    • Situational / behavioral questions
    • Puzzles and guesstimates

Overall Selection Ratio:

  • Roughly 25 out of 100 candidates get selected overall
  • Tier variations:
    • Tier 2 colleges: 50/200
    • Tier 1 colleges: 30/50
    • IITs: Up to 8/10

About HCL Technologies

  • Full Name: HCL Technologies Limited (HCLTech)
  • Headquarters: Noida, India
  • Founder: Shiv Nadar
  • CEO: C. Vijayakumar
  • Industry: IT services, consulting, enterprise transformation, and business process outsourcing
  • Pioneer in modern computing innovations, including early personal computers based on 8-bit microprocessors.


HCL tech most 50+ Asked Technical Equations in interview

  1. What is the difference between JDK, JRE, and JVM?
    • JDK is the Java Development Kit used to develop Java programs. JRE is the Java Runtime Environment that runs Java programs. JVM is the Java Virtual Machine that converts bytecode into machine code, allowing programs to run on any platform.
  2. What are pointers in C/C++?
    • A pointer is a variable that stores the memory address of another variable. Pointers are widely used in dynamic memory allocation, arrays, and function calls. Mismanagement can lead to segmentation faults.
  3. Explain call by value and call by reference.
    • Call by value passes a copy of the variable to a function, so changes don’t affect the original variable. Call by reference passes the actual memory address, so changes affect the original variable.
  4. What are arrays and linked lists? Difference between them.
    • Arrays store elements in contiguous memory locations with fixed size. Linked lists consist of nodes connected via pointers, allowing dynamic size but with slower element access.
  5. Write a program to reverse a string.
    • Reversing a string involves iterating from the end to the beginning and storing characters in a new string or swapping in place. This tests basic programming and string manipulation skills.
  6. What is recursion? Write a recursive program for factorial.
    • Recursion is when a function calls itself. Factorial of n is calculated as n * factorial(n-1) with base case factorial(0) = 1. Interviewers test understanding of recursion depth and base cases.
  7. Difference between stack and heap memory.
    • Stack is memory for static allocation (local variables, function calls), automatically managed, with limited size. Heap is for dynamic allocation, manually managed, and slower but larger.
  8. What is method overloading and method overriding in Java?
    • Overloading allows multiple methods with the same name but different parameters. Overriding allows a subclass to redefine a method of the parent class with the same signature for runtime polymorphism.
  9. What are constructors and destructors?
    • Constructors initialize an object when it is created. Destructors are called when an object is destroyed to release resources. Constructors can be parameterized or default.
  10. Explain static and dynamic memory allocation.
    • Static memory is allocated at compile-time (e.g., arrays). Dynamic memory is allocated at runtime using malloc, calloc, new, etc., allowing flexible memory usage but requiring deallocation.

Data Structures and Algorithms (DSA)

  1. What is a stack? Implement push and pop operations.
    • A stack is LIFO (Last-In-First-Out). Push adds an element to the top; pop removes the top element. Useful in recursion, expression evaluation, and undo operations.
  2. What is a queue? Difference between queue and stack.
    • Queue is FIFO (First-In-First-Out). Stack is LIFO. Queues are used in scheduling and buffering tasks, while stacks are used for reversing or recursion management.
  3. Explain a linked list and types of linked lists.
    • A linked list consists of nodes with data and a pointer to the next node. Types include singly linked, doubly linked, and circular linked lists. They allow dynamic memory allocation and insertion/deletion flexibility.
  4. Reverse a linked list.
    • Reversing involves changing the next pointers of nodes so the first becomes last and vice versa. Both iterative and recursive methods are tested in interviews.
  5. What is a binary tree? Types of traversal?
    • A binary tree is a hierarchical structure with nodes having at most two children. Traversals include in-order, pre-order, post-order (DFS), and level-order (BFS).
  6. Implement binary search on a sorted array.
    • Binary search divides the array into halves, reducing the search space to O(log n). Candidates must handle base conditions and mid calculations correctly.
  7. What is a hash table? Difference with hashmap?
    • Hash table stores key-value pairs with O(1) average access time. HashMap (Java) allows null keys and values and is not synchronized, while Hashtable is synchronized and disallows null.
  8. Explain dynamic programming with an example.
    • DP breaks problems into overlapping subproblems and stores results in memory (memoization or tabulation). Example: Fibonacci sequence or knapsack problem.
  9. What is a circular queue?
    • A circular queue treats the array as circular to efficiently use memory and prevent “false overflow.” It’s implemented using front and rear pointers.
  10. Implement a stack using two queues.
    • This tests understanding of data structures and problem-solving, where stack operations (LIFO) are simulated using queue operations (FIFO).

Database / SQL Questions

  1. What is DBMS? Difference with RDBMS.
    • DBMS manages data storage and retrieval. RDBMS organizes data in tables with relationships, supports SQL, and enforces constraints.
  2. Explain primary key, foreign key, and candidate key.
    • Primary key uniquely identifies a row. Foreign key links tables. Candidate keys are potential primary keys.
  3. What are joins? Types of joins in SQL.
    • Joins combine data from multiple tables. Types: INNER, LEFT, RIGHT, FULL OUTER. They test ability to retrieve relational data efficiently.
  4. Explain normalization and its forms (1NF, 2NF, 3NF).
    • Normalization reduces redundancy and ensures data integrity. 1NF eliminates repeating groups, 2NF removes partial dependency, 3NF removes transitive dependency.
  5. What are ACID properties in DBMS?
    • ACID ensures reliable transactions: Atomicity, Consistency, Isolation, Durability. It prevents data corruption and ensures database integrity.
  6. Write a query to find the second highest salary in a table.
    • Typically solved using LIMIT, OFFSET, or subqueries. Tests SQL query formulation and logical thinking.
  7. Difference between clustered and non-clustered index.
    • Clustered index stores data rows in order of the key; only one per table. Non-clustered stores a separate pointer to rows; multiple can exist.
  8. Explain a trigger in SQL.
    • A trigger is a set of actions executed automatically in response to events (INSERT, UPDATE, DELETE) on a table.
  9. What is a stored procedure?
    • A stored procedure is a precompiled SQL program stored in the database to perform repeated tasks efficiently.
  10. What is a view in SQL?
    • A view is a virtual table derived from a query. It does not store data physically but allows simplified query access and security.

OOPs / Concepts

  1. Explain OOPS concepts in brief.
    • Object-Oriented Programming uses objects to represent real-world entities. Key concepts: Encapsulation, Abstraction, Inheritance, Polymorphism.
  2. What is inheritance? Types of inheritance.
    • Inheritance allows a class to acquire properties/methods of another. Types: Single, Multiple, Multilevel, Hierarchical, Hybrid.
  3. Explain polymorphism with examples.
    • Polymorphism allows methods to take many forms. Compile-time (overloading) and runtime (overriding) are common examples.
  4. What is encapsulation?
    • Encapsulation binds data and methods in a class, restricting direct access and exposing via getters/setters.
  5. What is abstraction?
    • Abstraction hides implementation details and exposes functionality through interfaces or abstract classes.
  6. Explain constructor vs destructor.
    • Constructor initializes an object; destructor releases resources when the object goes out of scope.
  7. Difference between abstract class and interface.
    • Abstract class can have method implementations; interface can only have abstract methods (before Java 8). Interface supports multiple inheritance.
  8. What is a virtual function in C++?
    • Virtual functions enable runtime polymorphism. The function called is determined by the object type at runtime.
  9. Explain access modifiers in OOP.
    • Access modifiers define visibility: private (within class), protected (within package & subclass), public (globally).
  10. Difference between method overloading and overriding.
    • Overloading: same method name, different parameters. Overriding: subclass redefines parent class method with same signature.

Computer Fundamentals / OS / Misc

  1. Difference between stack and heap memory.
    • Stack is for static allocation, function calls, fast but limited. Heap is for dynamic allocation, slower but flexible.
  2. What is deadlock? How to prevent it?
    • Deadlock occurs when processes wait indefinitely for resources. Prevention: resource ordering, wait-die, or timeout mechanisms.
  3. What is virtual memory?
    • Virtual memory allows execution of processes larger than physical memory using disk storage as temporary memory.
  4. What is a process and a thread?
    • Process: an executing program with separate memory. Thread: lightweight sub-process sharing memory with other threads in the process.
  5. Difference between TCP and UDP.
    • TCP is connection-oriented, reliable, slower. UDP is connectionless, faster, unreliable. Used in streaming vs file transfer.
  6. What is OS scheduling?
    • OS schedules CPU time among processes using algorithms like FCFS, SJF, Round Robin, Priority Scheduling.
  7. What is a file system?
    • File system manages storage and retrieval of data on storage devices, organizing data into files, directories, and metadata.
  8. Explain DNS and IP address.
    • DNS converts domain names into IP addresses. IP address uniquely identifies devices in a network.
  9. What is multithreading?
    • Multithreading allows concurrent execution of multiple threads within a process to improve performance.
  10. Explain memory management in programming.
    • Memory management involves allocating, deallocating, and organizing memory efficiently. Languages like C/C++ require manual allocation; Java/Python use garbage collection.
  11. Difference between procedural and OOP languages.
    • Procedural programming is function-based (C), while OOP is object-based (Java, C++), promoting modularity, reusability, and abstraction.

HCL top 20 Technical interview questions

Question 1:

How is C different from C++? 

Explanation:


Question 2:

What is cloud computing, the application of cloud computing, SAAS?

Explanation:

Cloud Computing: It is an application-based software infrastructure. It stores data on remote servers, these data can then be accessed through the internet.

Basically, it can be defined as a service that delivers and stores data throughout the internet through servers.

SAAS: It stands for Software as a Service.

  • SAAS is a software distribution model, where a cloud provider can host applications and make them available to users over the internet.
  • SAAS along with IAAS and PAAS are the major categories of cloud computing.

Question 3:

What is Machine Learning?

Explanation:

Machine learning is a branch of AI. It is the study and creation of computer algorithms that can improve themselves through experience or data.

Machine learning algorithms work on a sample model known as “training data” which helps them to make predictions and decisions on its own without being programmed by anyone.

These algorithms are based on computational statistics and mathematical models which are used for finding patterns in data and make predictions based on these patterns.


Question 4:

Benefits of Stored Procedures?

Explanation:

It is a subroutine available to applications that access a relational database management system.

There are many benefits of the Stored Procedure.

Benefits include:

  • It has a Better Performance
  • Ease of use.
  • Enables us to take advantage of the computing resources of the server.
  • Provides scalability, maintainability, security.

Question 5:

What is a deadlock in DBMS?

Explanation:

An unwanted situation in which two or more transactions are waiting indefinitely for one another to give up locks is known as deadlock. Deadlock is said to be one of the most feared complications in DBMS as it brings the whole system to a Halt.

Question 6:

What is garbage collection in C?

Explanation:

Garbage Collection (GC) is a mechanism that provides automatic memory reclamation for unused memory blocks. Programmers dynamically allocate memory, but when a block is no longer needed, they do not have to return it to the system explicitly with a free() call.

Question 7:

What are the four basic principles of OOPS?

Explanation:

The four basic principles of OOPS are:

  1. Encapsulation – It is the mechanism that binds the code to the data it manipulates. Thus the data is wrapped under a single unit.
  2. Abstraction – It is the process of exposing the details that are necessary and hiding the rest. The use of this process is to reduce the object to its essence such that only the necessary characteristics are exposed to the users.
  3. Inheritance – It is a property of JAVA through which it can acquire the property of one class to another class. There is a parent class whose attributes and methods are inherited by the child class or subclass.
  4. Polymorphism – It is the ability of JAVA to perform the same action in many different ways. Through this property, a single task can be performed in multiple ways. It is the ability of an object to take many forms.

Question 8:

Difference between binary and counting semaphores.

Explanation:

Semaphore has two fields in which one field is that it is a positive variable and shared between threads. A semaphore is a signaling mechanism, and a thread that is waiting on a semaphore can be signaled by another thread.

  •  Binary semaphore – Is restricted to only two values i.e. zero or one
  • Counting semaphore – Is restricted to any non-negative integer value

Question 9:

What is abstraction?

Explanation:

 It is the process of selecting data from a larger dataset to show only the relevant details of the object. It is the concept of object-oriented programming. Abstraction is hiding unnecessary details from the users to reduce the complexity of viewing things and to increase security.


Question 10:

What are public IP and Private IP?

Explanation:

Both Addresses are used to uniquely identify a machine on the internet. A public IP address uses a wider area means it is used to communicate within the wider network and all the information you’re searching for can find you.. Whereas Private IP uses the same network it means it is used to communicate within the same network.that is, it  operates with a local network.


Question 11:

How can you create threads in JAVA?

Explanation:

Threads are created in JAVA by implementing the runnable interface and overriding the run() method.


Question 12:

Write a code for checking whether a character is a alphabet or not.

Explanation:

ch = input(“Insert any character: “)

if ‘a’ <= ch <= ‘z’ or ‘A’ <= ch <= ‘Z’:

    print(“The inserted character”, ch, “is an Alphabet”)

else:

    print(“The inserted character”, ch, “is not an Alphabet”)


Question 13:

Write a program for reversing an array.

Explanation:

def reverseList(A, start, end):

  while start < end:

    A[start], A[end] = A[end], A[start]

    start += 1

    end -= 1

# Driver function to test above function

A = [10, 20, 30, 40, 50]

reverseList(A, 0, 4)

print(A)


Question 14:

What are tokens in C++?

Explanation:

  • Token is the smallest element of a C++ program that contains meaning for the compiler.
  • Types of tokens include: Keywords, Identifiers, Strings etc.
  • Tokens basically act as building blocks of a program.

Question 15:

How to see object methods in Python?

Explanation:

Using the help() command.


Question 16:

What is a cursor in SQL?

Explanation:

A cursor is defined as a temporary space created in memory when an SQL command is executed.

It is of two types:

  1. Implicit cursor – An Implicit cursor is automatically created when a statement is executed.
  2. Explicit cursor –  An explicit cursor needs to be defined by the user. It can be defined by providing a name.

Question 17:

What is an empty interface in java?

Explanation:

An empty interface does not contain any methods or fields. By implementing an empty interface a class exhibits special behavior with respect to the interface implemented.

An empty interface is also  called a Marker Interface.


Question 18:

What is the Collection API?

Explanation:

Collection API provides a set of classes and interfaces that makes it easier to work with collections of objects such as lists, maps etc.


Question 19:

What is a friend function in C++?

Explanation:

A friend function is a function that can access private, protected and public members of a class. It is specified outside the class but can access all its members. It is declared using the friend keyword.


Question 20:

Write a code for Binary Search in Java.

Explanation:

public class Main{

    public static int binarySearch(int array[], int left, int right, int item){

        if (right >= left){

            // calculation of new mid

            int mid = left + (right – left)/2;

            // returns position where found

            if (array[mid] == item)

                return mid+1;

            // goes to recursive calls in left half

            if (array[mid] > item)

                return binarySearch(array, left, mid-1, item);

                // goes to recursive calls in right half

            else

                return binarySearch(array, mid+1, right, item);

        }

        // if element is not found we return -1

        else

            return -1;

    }

    public static void main(String args[]){

        int[ ] array = {10, 20, 30, 40, 50, 60, 70, 80};

        int item = 70;

        int size = array.length;

        int position = binarySearch(array, 0, size-1, item);

        if(position == -1)

            System.out.println(“Element not found”);

        else

            System.out.println(“The value ” + item + ” found at position: ” + position);

    }

}

// Time complexity O(Log N)

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