<aside> Collections in C# allow us to work with groups of objects. Each type has unique benefits for different scenarios.

📝 List

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A List is like a flexible array - it can grow or shrink as needed.

// Creating Lists
List<string> cities = new List<string>();
List<string> cities = new List<string> { "København", "Aalborg", "Odense" };

// Adding items
cities.Add("Roskilde");
cities.Insert(2, "Sorø");

🎯 Queue

Queues use First-In-First-Out (FIFO) - like a line at a store.

Queue<string> customers = new Queue<string>();
customers.Enqueue("Customer 1");   // Add to end
string next = customers.Dequeue(); // Remove from front
string peek = customers.Peek();    // Look at front

📚 Stack

Stacks use Last-In-First-Out (LIFO) - like a stack of plates.

Stack<string> cards = new Stack<string>();
cards.Push("Spar Es");        // Add to top
string top = cards.Pop();     // Remove from top
string peek = cards.Peek();   // Look at top

📖 Dictionary<TKey, TValue>

Dictionaries store key-value pairs for quick lookups.

Dictionary<string, int> grades = new Dictionary<string, int>();
grades.Add("Alice", 95);
grades["Bob"] = 87;

// Safe access
if (grades.TryGetValue("Alice", out int grade))
{
    Console.WriteLine($"Grade: {grade}");
}

📊 When to Use Each

<aside> 💡 Best Practices: • Use plural names for collections • Choose appropriate type for your needs • Handle errors when accessing items • Check for null/empty collections

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