In this lesson, we’ll cover various methods that make lists easy to work with. We’ll explore different ways to manipulate and interact with lists beyond just List.Add(). These methods and many more exist to help you manipulate and interact with lists effectively. Refer to the official documentation at the end of this lesson for a complete list of methods and properties.
Example List
We’ll use this list of movies as our example throughout this introduction:
List<string> movies = [
"Jurassic Park",
"Toy Story",
"Mortal Kombat",
"Braveheart",
"Big Daddy",
"Armageddon",
"Forrest Gump",
"True Lies",
"The Matrix",
"The Lion King"
];
List.Clear() - Removes all elements from the list.
movies.Clear();
Console.WriteLine(movies.Count); // Outputs 0
List.Contains(item) - Determines whether an element is in the list. Returns true if the element is found; otherwise, false.
bool containsToyStory = movies.Contains("Toy Story"); // returns true
bool containsBugsLife = movies.Contains("A Bug's Life"); // returns false
List.IndexOf(item) - Returns the index of the first occurrence of a value in the list. If not found, returns -1.
int indexOfToyStory = movies.IndexOf("Toy Story"); // returns 1
int indexOfBugsLife = movies.IndexOf("A Bug's Life"); // returns -1
List.Insert(index, item) - Inserts an element into the list at the specified index. Elements at or to the right of the index get shifted to the right.
movies.Insert(2, "Toy Story 2");
[
"Jurassic Park",
"Toy Story",
"Toy Story 2",
"Mortal Kombat",
"Braveheart",
"Big Daddy",
"Armageddon",
"Forrest Gump",
"True Lies",
"The Matrix",
"The Lion King"
]
List.Remove(item) - Removes the first occurrence of a specific object from the list. Returns true if the item was sucessfully removed; otherwise, false.
bool removed = movies.Remove("Jurassic Park");
[
"Toy Story",
"Mortal Kombat",
"Braveheart",
"Big Daddy",
"Armageddon",
"Forrest Gump",
"True Lies",
"The Matrix",
"The Lion King"
]
List.RemoveAt(index) - Removes the element at the specified index of the list.
movies.RemoveAt(5);
[
"Jurassic Park",
"Toy Story",
"Mortal Kombat",
"Braveheart",
"Big Daddy",
"Forrest Gump",
"True Lies",
"The Matrix",
"The Lion King"
]
List.Reverse() - Reverses the order of the elements in the list.
movies.Reverse();
[
"The Lion King",
"The Matrix",
"True Lies",
"Forrest Gump",
"Armageddon",
"Big Daddy",
"Braveheart",
"Mortal Kombat",
"Toy Story",
"Jurassic Park"
]
List.Sort() - Sorts the elements in the list.
movies.Sort();
[
"Armageddon",
"Big Daddy",
"Braveheart",
"Forrest Gump",
"Jurassic Park",
"Mortal Kombat",
"The Lion King",
"The Matrix",
"Toy Story",
"True Lies"
]
bool managingInventory = true;
List<string> inventory = [
"axe",
"shovel",
"axe",
"rope",
"tent",
"grill",
"poncho",
"sleeping bag",
"flint",
"sleeping bag"
];
Console.WriteLine("--- Inventory Manager ---");
while (managingInventory)
{
Console.WriteLine("\n-Main Menu-");
Console.WriteLine("1) List inventory");
Console.WriteLine("2) Add new item");
Console.WriteLine("3) Insert new item");
Console.WriteLine("4) Find item");
Console.WriteLine("5) Sort inventory");
Console.WriteLine("6) Remove an item");
Console.WriteLine("7) Delete inventory");
Console.WriteLine("8) Exit");
Console.Write("-> ");
string input = Console.ReadLine();
if (input == "1")
{
Console.WriteLine("-Inventory-");
if (inventory.Count == 0)
{
Console.WriteLine("No inventory.");
}
else
{
foreach (string item in inventory)
{
Console.WriteLine("- " + item);
}
}
}
else if (input == "2")
{
Console.Write("New Item: ");
input = Console.ReadLine();
inventory.Add(input);
Console.WriteLine(input + " added to list.");
}
else if (input == "3")
{
Console.Write("New Item: ");
input = Console.ReadLine();
Console.Write($"Which index? (0-{inventory.Count - 1}): ");
int index = Convert.ToInt32(Console.ReadLine());
// Validate index
if (index >= 0 && index < inventory.Count)
{
inventory.Insert(index, input);
Console.WriteLine(input + " inserted into list.");
}
else
{
Console.WriteLine("Invalid index.");
}
}
else if (input == "4")
{
Console.Write("Which item? ");
input = Console.ReadLine();
int index = inventory.IndexOf(input);
if (index >= 0)
{
Console.WriteLine($"{input} located at index {index}");
}
else
{
Console.WriteLine("Item not found.");
}
}
else if (input == "5")
{
Console.WriteLine("Sorting inventory.");
inventory.Sort();
}
else if (input == "6")
{
Console.Write("Which item? ");
input = Console.ReadLine();
bool itemRemoved = inventory.Remove(input);
if (itemRemoved)
{
Console.WriteLine(input + " removed.");
}
else
{
Console.WriteLine(input + " not found, or an error occurred.");
}
}
else if (input == "7")
{
// Clear the inventory
Console.Write("Are you sure? (y/n) ");
input = Console.ReadLine();
if (input == "y")
{
inventory.Clear();
Console.WriteLine("Inventory cleared.");
}
else
{
Console.WriteLine("Canceled.");
}
}
else if (input == "8")
{
Console.WriteLine("Exiting.");
managingInventory = false;
}
else
{
Console.WriteLine("Invalid selection. Please choose a valid option.");
}
}
--- Inventory Manager ---
-Main Menu-
1) List inventory
2) Add new item
3) Insert new item
4) Find item
5) Sort inventory
6) Remove an item
7) Delete inventory
8) Exit
-> 6
Which item? flint
flint removed.
-Main Menu-
1) List inventory
2) Add new item
3) Insert new item
4) Find item
5) Sort inventory
6) Remove an item
7) Delete inventory
8) Exit
-> 5
Sorting inventory.
-Main Menu-
1) List inventory
2) Add new item
3) Insert new item
4) Find item
5) Sort inventory
6) Remove an item
7) Delete inventory
8) Exit
-> 3
New Item: charcoal
Which index? (0-8): 0
charcoal inserted into list.
-Main Menu-
1) List inventory
2) Add new item
3) Insert new item
4) Find item
5) Sort inventory
6) Remove an item
7) Delete inventory
8) Exit
-> 1
-Inventory-
- charcoal
- axe
- axe
- grill
- poncho
- rope
- shovel
- sleeping bag
- sleeping bag
- tent
-Main Menu-
1) List inventory
2) Add new item
3) Insert new item
4) Find item
5) Sort inventory
6) Remove an item
7) Delete inventory
8) Exit