Here's a cheat sheet for common methods and operations on List in C#:

Creating and Initializing Lists

List<int> numbers = new List<int>(); // Empty list
List<string> names = new List<string> { "Alice", "Bob", "Charlie" }; // Initialized with elements

Adding Elements

numbers.Add(10); // Adds a single item
numbers.AddRange(new int[] { 20, 30, 40 }); // Adds a collection of items

Accessing Elements

int firstNumber = numbers[0]; // Access by index
int lastNumber = numbers[numbers.Count - 1]; // Last element

Removing Elements

numbers.Remove(20); // Removes the first occurrence of 20
numbers.RemoveAt(0); // Removes element at index 0
numbers.RemoveAll(n => n > 30); // Removes all elements matching the condition
numbers.Clear(); // Removes all elements from the list

Checking Existence

bool containsBob = names.Contains("Bob");
int index = names.IndexOf("Charlie"); // Returns index of first occurrence or -1 if not found

Sorting and Reversing

numbers.Sort(); // Sorts the list
numbers.Reverse(); // Reverses the list

Iterating Through List

foreach (var name in names)
{
    Console.WriteLine(name);
}

List Information

int count = numbers.Count; // Number of elements in the list
bool isEmpty = numbers.Count == 0; // Checks if list is empty

Converting to Array

int[] numbersArray = numbers.ToArray(); // Converts list to array

Finding Elements

List<string> results = names.FindAll(name => name.Length > 4); // Finds all elements matching the condition
string foundName = names.Find(name => name.StartsWith("A")); // Finds first element matching the condition

Copying and Cloning

List<int> copy = new List<int>(numbers); // Copies the list
List<int> clone = numbers.ToList(); // Clones the list

These are some of the most commonly used methods and operations on List in C#. They should cover a wide range of scenarios for manipulating and working with lists effectively.

Of course! Here are some additional operations and methods you might find useful when working with List in C#:

Inserting and Removing Range

numbers.Insert(2, 25); // Inserts 25 at index 2, shifting subsequent elements
numbers.InsertRange(1, new int[] { 15, 20 }); // Inserts a collection starting at index 1
numbers.RemoveRange(3, 2); // Removes 2 elements starting from index 3

Checking and Modifying List

numbers.Exists(n => n > 50); // Checks if any element satisfies the condition
numbers.TrueForAll(n => n > 0); // Checks if all elements satisfy the condition
numbers.ConvertAll(n => n.ToString()); // Converts all elements to another type

Range Operations

List<int> subList = numbers.GetRange(1, 3); // Gets elements from index 1 to 3 (exclusive)

Sorting with Comparer

numbers.Sort((x, y) => y.CompareTo(x)); // Custom sorting with a comparer

Binary Search

numbers.Sort();
int index = numbers.BinarySearch(30); // Performs binary search, requires sorted list

Checking Subsets

List<int> subset = new List<int> { 20, 30 };
bool isSubset = subset.All(item => numbers.Contains(item)); // Checks if subset exists in numbers

LINQ Integration

using System.Linq;

var sortedNumbers = numbers.OrderBy(n => n); // Sorting using LINQ
var filteredNames = names.Where(name => name.Length > 4); // Filtering using LINQ

Synchronizing Access

List<int> synchronizedList = List.Synchronized(numbers); // Creates a thread-safe wrapper

List Capacity Management

numbers.Capacity = 50; // Adjusts the capacity of the list
numbers.TrimExcess(); // Reduces the capacity to match the count

Enumeration

IEnumerator<int> enumerator = numbers.GetEnumerator();
while (enumerator.MoveNext())
{
    int current = enumerator.Current;
    // Do something with current element
}

These additional operations should cover a broad range of functionalities and scenarios when working with lists in C#. They provide flexibility and efficiency for managing collections of elements in your applications.

List Method Cheat-Sheet