List in c#

List is a class in C# that represents a generic collection of objects, similar to an array but with additional functionality. Here’s an example of using List to store and manipulate a collection of integers:

using System;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        // Create a List of integers
        List<int> numbers = new List<int>();

        // Add some numbers to the list
        numbers.Add(1);
        numbers.Add(2);
        numbers.Add(3);

        // Display the contents of the list
        Console.WriteLine("Numbers in list:");
        foreach (int number in numbers)
        {
            Console.WriteLine(number);
        }

        // Insert a number at a specific index
        numbers.Insert(1, 5);

        // Remove a number from the list
        numbers.Remove(3);

        // Sort the list
        numbers.Sort();

        // Display the sorted list
        Console.WriteLine("Numbers in sorted list:");
        foreach (int number in numbers)
        {
            Console.WriteLine(number);
        }
    }
}

In this example, we first create an empty List<int> object called numbers. We then add some integers to the list using the Add method. We use a foreach loop to display the contents of the list.

Next, we use the Insert method to insert the number 5 at index 1 in the list. We then use the Remove method to remove the number 3 from the list. Finally, we use the Sort method to sort the list in ascending order.

We then use another foreach loop to display the contents of the sorted list.

Here are some other useful methods provided by the List class:

• Count: Returns the number of elements in the list.
• Contains: Determines whether an element is in the list.
• IndexOf: Returns the index of the first occurrence of an element in the list.
• Clear: Removes all elements from the list.
• ToArray: Copies the elements of the list to a new array.

Here’s an example that demonstrates some of these methods:

// Create a List of strings
List<string> colors = new List<string>();
colors.Add("red");
colors.Add("green");
colors.Add("blue");

// Check if a color is in the list
if (colors.Contains("green"))
{
    Console.WriteLine("Green is in the list");
}

// Find the index of a color in the list
int index = colors.IndexOf("blue");
Console.WriteLine("Blue is at index {0}", index);

// Remove a color from the list
colors.Remove("green");

// Convert the list to an array
string[] colorArray = colors.ToArray();

It’s important to note that List provides many other useful properties and methods for working with collections, such as AddRange to add a collection of elements to the list, RemoveAt to remove an element at a specific index, and GetEnumerator to get an enumerator that iterates through the list.