1. Solid principles implementation in a given scenario, how can we apply and improve the problem shared by interviewer. 2. C# coding questions on strings and arrays. 3. Rest API methods and it's implementation. 4. Basic questions on Jquery, ajax , mvc. 5. OOPS concepts

Question

Accepted Answer

Interview questions on software development concepts including SOLID principles, C# coding, REST API, jQuery, AJAX, MVC, and OOP.

For SOLID principles, explain how each principle can be applied to the given scenario and suggest improvements.
C# coding questions may include manipulating strings and arrays.
Rest API methods and implementation should be discussed, including HTTP methods and response codes.
Basic knowledge of jQuery, AJAX, and MVC architecture is expected.
OOP concepts such as inheritance, polymorphism, and encapsulation may be covered.

Accepted Answer

1. SOLID Principles – Scenario & How to Improve
"Let’s say we have a class that handles both order processing and sending emails. That’s a problem because it's doing too much. To apply Single Responsibility, I’d split it into two classes — one for processing, another for communication.

Then I’d use Dependency Inversion so the order processor doesn’t care how the email is sent — it just knows that something else handles it. This way, changes in one part don’t break others, and it becomes easier to test and maintain. That’s how SOLID helps — by keeping the code clean and future-proof."

2. C# – String & Array Questions
String Reversal (without inbuilt)
"If asked to reverse a string manually, I’d loop from both ends and swap characters until the middle — without using built-in functions like Reverse(). This approach is straightforward and efficient."

Finding Duplicates in Array
"I’d use a HashSet to track numbers I've already seen. If I find a number again, I know it’s a duplicate. It’s fast and uses minimum extra space."

3. REST API Methods & Implementation
"REST APIs work on standard methods:

GET to fetch,

POST to create,

PUT to update fully,

PATCH for partial updates,

DELETE to remove data.

In real-life, I follow clean API design — return proper status codes, use meaningful URIs, and handle errors gracefully. I also make sure to separate request models from domain models to avoid overposting."

4. jQuery, AJAX, MVC – Basics
"jQuery helps in writing less code for common JavaScript tasks like DOM updates and AJAX calls. For example, using jQuery I can make background API calls to update a webpage without refreshing.

MVC stands for Model-View-Controller. It’s all about organizing the app. The model is the data, the view shows it to the user, and the controller handles the input logic. This separation makes the app cleaner and easier to manage."

5. OOPs Concepts – Your Style Explanation
"Encapsulation is like locking internal logic in a box and only exposing what’s needed.
Abstraction means focusing only on what matters — like driving a car without knowing how the engine works.
Inheritance is reusing features — like a child class getting traits from a parent.
Polymorphism means one name, different actions — like ‘makeSound’ doing different things for a dog and a cat.

These four pillars help us write flexible and organized code that’s easy to scale and manage."

Asked in Fiserv

1. Solid principles implementation in a given scenario, how can we apply and improve the problem shared by interviewer. 2. C# coding questions on strings and arrays. 3. Rest API methods and it's implementation. 4. Basic questions on Jquery, ajax , mvc. 5. OOPS concepts

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