How to empty a list in C#?

Question

I want to empty a list. How to do that?

Answer 1

Option #1: Use Clear() function to empty the List<T> and retain it's capacity.

• Count is set to 0, and references to other objects from elements of the collection are also released.

• Capacity remains unchanged.

Option #2 - Use Clear() and TrimExcess() functions to set List<T> to initial state.

• Count is set to 0, and references to other objects from elements of the collection are also released.

• Trimming an empty List<T> sets the capacity of the List to the default capacity.

Definitions

Count = number of elements that are actually in the List<T>

Capacity = total number of elements the internal data structure can hold without resizing.

Clear() Only

List<string> dinosaurs = new List<string>();    
dinosaurs.Add("Compsognathus");
dinosaurs.Add("Amargasaurus");
dinosaurs.Add("Deinonychus");
Console.WriteLine("Count: {0}", dinosaurs.Count);
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);
dinosaurs.Clear();
Console.WriteLine("\nClear()");
Console.WriteLine("\nCount: {0}", dinosaurs.Count);
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);

Clear() and TrimExcess()

List<string> dinosaurs = new List<string>();
dinosaurs.Add("Triceratops");
dinosaurs.Add("Stegosaurus");
Console.WriteLine("Count: {0}", dinosaurs.Count);
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);
dinosaurs.Clear();
dinosaurs.TrimExcess();
Console.WriteLine("\nClear() and TrimExcess()");
Console.WriteLine("\nCount: {0}", dinosaurs.Count);
Console.WriteLine("Capacity: {0}", dinosaurs.Capacity);