PWC Full Stack Developer Interview Experience

What is the difference between an abstract class and an interface in .NET?

Explain the difference between Web API and REST.

What is the difference between PUT and PATCH HTTP methods? Provide an example of how each was used in your project.

What is the difference between `Thread.Sleep` and `Task.Delay` in .NET?

What is the difference between `IEnumerable` and `IQueryable` in .NET?

What is the difference between `var` and `dynamic` in C#?

Explain how to implement Cross-Origin Resource Sharing (CORS) in a .NET application.

How do you implement a custom exception in .NET?

What is the difference between `System.Text.Json` and `Newtonsoft.Json`?

How do you implement and handle migration from .NET 6 to .NET 8?

Why did you use Azure Cosmos DB in your project? Which partition key was selected and why? What are the disadvantages of Cosmos DB?

How do you implement and measure code coverage for a .NET application?

Write a C# method that returns the second highest distinct number in an integer array. Input: `[10, 5, 20, 8, 20]` Output: `10` (since 20 is the highest and 10 is the next distinct value)

input: [10, 5, 20, 8, 20]
output: 10

Explain what React hooks are and why they are used.

Explain the differences between: - `useMemo` vs `useCallback` - `useState` vs `useEffect`

Explain what prop drilling is in React and how it can be avoided.

Explain lifecycle methods in React and how functional components replicate them.

How do you implement client-side routing in a React application?

Explain how abstraction works in React hooks and when to extract logic into custom hooks.

What strategies and best practices can you use to improve performance in a React application?

How do you implement and configure RTK Query in a React application?

Build a controlled React search component with the following requirements: - Bind a text input to React state. - Wait 400ms after the user stops typing before making a `GET /api/employees?q=term` call. - If the trimmed query length is less than 2 characters, do not call the API; clear results and display "Type at least 2 characters". - While the request is pending, display "Searching…". - If the user types again before the previous request finishes, ignore or abort the previous request using `AbortController` to avoid race conditions. - Display a user-friendly error message on failure. - Implement using React hooks only.