C# Development for Beginners #16: Collections - Lists and Arrays - Managing Groups of Data
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Video Description
Real programs don't work with one variable at a time - they manage hundreds or thousands of items. Let's master collections in C#!
What you'll learn: • Arrays - Fixed-size collections with indexed access • Lists - Dynamic collections that grow as needed • Dictionary - Lightning-fast key-value lookups • HashSet - Automatic duplicate prevention • How collections relate through interfaces (IEnumerable, IList) • When to use each collection type • Common gotchas (IndexOutOfRangeException, modifying during foreach) • Performance characteristics (Big O notation simplified) • Combining collections (Dictionary of Lists!)
Key insights: • List is your default choice 90% of the time • Arrays are rare in modern C# (fixed size is limiting) • Dictionary lookups are O(1) - nearly instant! • HashSet.Contains() beats List.Contains() for large data • All collections implement IEnumerable (that's why LINQ works!)
We'll build: • Grade tracker using multiple collection types • Real examples with student data • Collections inside collections
Previous Video: [Video 15 Title] Next Video: LINQ - Query Your Data ► Full Playlist: https://www.youtube.com/playlist?list=PLGxFXI4dC2shfDgudNdh1FtSLcAZG0-Ba ► Code Repository: https://github.com/benday-inc/csharp-for-beginners-2025
Finally understanding when to use List vs Dictionary? Smash that like button! Subscribe and hit the bell - LINQ is next and it's going to change everything. What collection type confused you the most when starting out? Let me know below!
#CSharp #Collections #Lists #Arrays #Dictionary #HashSet #DotNet #Programming #DataStructures
0:00 Collections - Lists and Arrays 0:31 The Problem With Single Variables 1:10 Two really important namespaces: 1:35 Arrays - Your First Collection 2:19 Common Array Mistake 3:30 Lists - Dynamic Collections 4:19 Array vs List 5:31 Dictionary - Key-Value Pairs 6:24 HashSet - Unique Items Only 7:13 How Collections Fit Together 8:04 How Do I Choose? 8:14 Choosing the Right Collection 8:52 Real-World Example 9:33 Common Collection Gotchas 10:15 Performance Quick Reference 11:05 Key Takeaways 11:57 Practice Challenge 12:46 Next up: LINQ
Video Info
- Duration: 13:10
- Published: November 10, 2025
