Lists

Arrays are great, but they have one big limitation — their size is fixed. What if you do not know how many items you will need? That is where List comes in. It is like an array that can grow and shrink dynamically.

Creating a List

List<string> names = new List<string>();
List<int> scores = new List<int> { 85, 92, 78, 95 };

The angle brackets <string> tell C# what type of data the list will hold. This is called a generic type. You can create lists of any type — strings, integers, custom objects, anything.

Adding and Removing Items

List<string> cities = new List<string>();

cities.Add("Kano");
cities.Add("Lagos");
cities.Add("Abuja");
Console.WriteLine(cities.Count);  // 3

cities.Insert(1, "Ibadan");  // Insert at index 1
// cities: Kano, Ibadan, Lagos, Abuja

cities.Remove("Lagos");      // Remove by value
cities.RemoveAt(0);          // Remove by index
// cities: Ibadan, Abuja

cities.Clear();              // Remove everything

See how easy it is? With arrays, you would have to create a new array and copy everything over. With List, it handles all of that behind the scenes.

Accessing and Searching

List<int> numbers = new List<int> { 10, 20, 30, 40, 50 };

Console.WriteLine(numbers[0]);       // 10
Console.WriteLine(numbers.Count);    // 5

int index = numbers.IndexOf(30);     // 2
bool has40 = numbers.Contains(40);   // true

numbers.Sort();
numbers.Reverse();

List has all the useful methods you would expect — IndexOf, Contains, Sort, Reverse, and more.

Looping Through a List

List<string> students = new List<string>
{
    "Amina", "Bilal", "Chukwuemeka", "Fatima"
};

// Using foreach
foreach (string student in students)
{
    Console.WriteLine(student);
}

// Using for (when you need the index)
for (int i = 0; i < students.Count; i++)
{
    Console.WriteLine($"{i + 1}. {students[i]}");
}

List vs Array

• Use Array when you know the exact size and it will not change
• Use List when you need to add or remove items dynamically
• Arrays are slightly faster, but the difference is negligible for most applications

In practice, you will use List much more often than arrays. It is more flexible and easier to work with.