Flatten list of lists using SelectMany?

Short answer: Flatten list of lists using SelectMany List<List<int>> numbers = new() { new() { 1, 2 }, new() { 3, 4 }, new() { 5 } var flat = numbers.SelectMany(n => n); Flatten list of lists using SelectMany List<List<int>> numbers = new() { new() { 1, 2 }, new() { 3, 4 }, new() { 5 } var flat = numbers.SelectMany(n => n); Real-world example… (ShopNest) ShopNest maps…… entities to DTOs with .Select(o => new OrderSummaryDto { Id…

Explain a bit more

= o.Id, Total = o.Total }) so the API does not leak internal fields. Flatten list of lists using SelectMany List<List<int>> numbers = new() { new() { 1, 2 }, new() { 3, 4 }, new() { 5 } var flat = numbers.SelectMany(n => n); Flatten list of lists using SelectMany List<List<int>> numbers = new() { new() { 1, 2 }, new() { 3, 4 }, new() { 5 } var flat = numbers.SelectMany(n => n); Real-world example… (ShopNest) ShopNest maps entities to DTOs with .Select(o => new OrderSummaryDto { Id = o.Id, Total = o.Total }) so the API does not leak internal fields.

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.