How do you get the index of an element in a List<T>?

Short answer: Use IndexOf(item) or FindIndex(predicate). Example: int index = list.IndexOf(10); int indexByCondition = list.FindIndex(x => x > 100); 📘 C# Dictionary<TKey, TValue> – Interview Questions & Answers

Example code

Use IndexOf(item) or FindIndex(predicate). Example: int index = list.IndexOf(10);
int indexByCondition = list.FindIndex(x => x > 100); 📘 C# Dictionary<TKey, TValue> – Interview Questions & Answers

Real-world example (ShopNest)

In ShopNest, an order page loads products with List<Product> so you can Add items to the cart and access them by index. Use IEnumerable<T> when you only need to loop (for example, printing invoice lines).

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.