C# Generics and Collections: The Interview Topic That Comes Up Every Single Time

Short summary

C# generics solve type-safety through reusable, constrained containers; collections like List, Dictionary, and HashSet are generic-based structures for different access patterns. Covariance and contravariance handle type relationships, and mastering all three is essential for interviews and production code.

• •Generics eliminate code duplication and unsafe casting by defining type parameters once and filling them in at use time
• •Constraints restrict what types a generic can accept, enabling safer and more expressive generic code
• •Collections (List, Dictionary, HashSet) are generic-based structures optimized for different access patterns

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