10 Questions — Jump to a topic

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1. 1. Explain the difference between a compiler and an interpreter.
2. 2. What is the difference between stack and heap memory?
3. 3. Explain OOP concepts with examples.
4. 4. What are the differences between C, C++, and Java?
5. 5. Explain SQL vs NoSQL databases.
6. 6. What are data structures and why are they important?
7. 7. Write a program to reverse a string.
8. 8. What is the difference between == and === in JavaScript?
9. 9. What are HTTP methods commonly used in APIs?
10. 10. How do you explain the SDLC (Software Development Life Cycle)?

Here are the 10 most frequently asked questions that freshers encounter in technical interviews. These cover basics of programming, databases, and problem-solving.

1. Explain the difference between a compiler and an interpreter.

• Compiler converts the entire source code into machine code before execution.
• Interpreter executes code line by line.

2. What is the difference between stack and heap memory?

• Stack: Stores local variables, method calls; fast but limited size.
• Heap: Stores objects; larger but slower memory allocation.

3. Explain OOP concepts with examples.

• Abstraction: Hiding details (e.g., abstract class).
• Encapsulation: Wrapping data and methods in a class.
• Inheritance: Reusing properties from another class.
• Polymorphism: Same method behaving differently in different contexts.

4. What are the differences between C, C++, and Java?

• C: Procedural language.
• C++: Supports both procedural and OOP.
• Java: Purely OOP, runs on JVM, platform-independent.

5. Explain SQL vs NoSQL databases.

• SQL: Relational, structured, schema-based (MySQL, SQL Server).
• NoSQL: Schema-less, flexible, for big data and documents (MongoDB).

6. What are data structures and why are they important?

• Ways to organize and store data efficiently.
• Examples: Array, Linked List, Stack, Queue, Tree, Graph.

7. Write a program to reverse a string.

• Answer:

  string str = "hello";
  char[] arr = str.ToCharArray();
  Array.Reverse(arr);
  Console.WriteLine(new string(arr));

8. What is the difference between == and === in JavaScript?

• ==: Compares values after type conversion.
• ===: Compares values and types strictly.

9. What are HTTP methods commonly used in APIs?

• GET, POST, PUT, DELETE, PATCH for CRUD operations.

10. How do you explain the SDLC (Software Development Life Cycle)?

• Phases: Requirement gathering → Design → Development → Testing → Deployment → Maintenance.

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Tip: Practice coding small programs, algorithms, and SQL queries daily.