Lists

C# List class is used to store and fetch elements. It can also have duplicate elements. It is found in System.Collections.Generic namespace. List class in C# represents a strongly typed list of objects. List provides functionality to create a list of objects, find list items, sort list, search list, and manipulate list items. In List, T is the type of object. What is the ‘T’ in List? List class represents a strongly typed list of objects. List provides functionality to create a list of objects, find list items, sort list, search list, and manipulate list items. In List, T is the type of objects. How to create List in C#? List is a generic class and is defined in the System.Collections.Generic namespace. You must import this namespace in your project to access the List class. using System.Collections.Generic; The List is a generic collection, so you need to specify a type parameter for the type of data it can store

The following example shows how to create a integer type list and add elements in list.

using System;
using System.Collections.Generic;


public class Program
{
	public static void Main()
	{
		// adding elements using add() method
		List Numbers = new List();
		Numbers.Add(1);
		Numbers.Add(2);
		Numbers.Add(3);
		Numbers.Add(4);
		
			   foreach(var i in Numbers)
			   {
				  Console.WriteLine("First number : " +  i);
			   }
	}
}
 

Output

First number : 1
First number : 2
First number : 3
First number : 4
 

The following example shows how to create a string type list and add elements in list.

using System;
using System.Collections.Generic;

public class Program
{
	public static void Main()
	{
		// adding elements using add() method
			var cities = new List();
			cities.Add("Yamuna Nagar");
			cities.Add("Kurukshetra");
			cities.Add("Panipat");
			cities.Add("Ambala");
		
			   foreach(var i in cities)
			   {
				  Console.WriteLine("City Name: " +  i);
			   }
	}
} 

Output

City Name: Yamuna Nagar
City Name: Kurukshetra
City Name: Panipat
City Name: Ambala
 

The following example shows how to adding elements using collection initializer syntax

using System;
using System.Collections.Generic;

public class Program
{
	public static void Main()
	{
		// adding elements using collection initializer syntax
		var cities = new List() {"Kurukshetra", "Panipat", "Ambala", "Yamuna Nagar"};
			   foreach(var i in cities)
			   {
				  Console.WriteLine("City Name: " +  i);
			   }
	}

} 

Output

City Name: Kurukshetra
City Name: Panipat
City Name: Ambala
City Name: Yamuna Nagar
 

The following example shows how to adding elements into list using classe

using System;
using System.Collections.Generic;
public class Program
{
	public static void Main()
	{
		var students = new List() { 
                new Student(){ Id = 1, Name="Shubham"},
                new Student(){ Id = 2, Name="mohit"},
                new Student(){ Id = 3, Name="Rohan"},
                new Student(){ Id = 4, Name="Rahul"}
            };
	
			foreach(var name in students)
			{
				Console.WriteLine("Student Name: " + name.Name);
			}
		
	}
}

class Student{
	public int Id { get; set; }
	public string Name { get; set; }
}
 

Output

Student Name: Shubham
Student Name: mohit
Student Name: Rohan
Student Name: Rahul
 

In the above example, List Numbers = new List(); creates a list of int type. In the same way, cities are string type list. You can then add elements in a list using the Add() method or the collection-initializer syntax. You can also add elements of the custom classes using the collection-initializer syntax. The following adds objects of the Student class in the List.

Example: Add Custom Class Objects in List

                var students = new List() { 
                new Student(){ Id = 1, Name="Shubham"},
                new Student(){ Id = 2, Name="mohit"},
                new Student(){ Id = 3, Name="Rohan"},
                new Student(){ Id = 4, Name="Rahul"}
 

using System;
using System.Collections.Generic;

public class Program
{
	public static void Main()
	{
		string[] cities = new string[3]{ "Kurukshetra", "Panipat", "Ambala" };

			var popularCities = new List();

			// adding an array in a List
			popularCities.AddRange(cities);

			var favouriteCities = new List();

			// adding a List 
			favouriteCities.AddRange(popularCities);
		
			foreach(var i in favouriteCities)
			  {
				  Console.WriteLine("City Name: " +  i);
			  }
	}

}	   
 

City Name: Kurukshetra
City Name: Panipat
City Name: Ambala
 

using System;
using System.Collections.Generic;
using System.Linq;
public class Program
{
	public static void Main()
	{
		var students = new List() { 
                new Student(){ Id = 1, Name="shubham" },
                new Student(){ Id = 2, Name="rahul" },
                new Student(){ Id = 3, Name="abir" },
                new Student(){ Id = 4, Name="shubham" },
				new Student(){ Id = 5, Name="mohit" }
		};
		
		//get all students whose name is shubham
		var Student = from s in students
			where s.Name == "shubham"
			select s;
		
		foreach(var student in Student)
			Console.WriteLine("student Id " + student.Id + " , student Name " +student.Name);
	}
}

public class Student
{ 
	public int Id { get; set; }
	public string Name { get; set; }
}
 

City Name: Kurukshetra
City Name: Panipat
City Name: Ambala
 

using System;
using System.Collections.Generic;
					
public class Program
{
	public static void Main()
	{
		List numbers = new List(){ 1,  3, 4 };

		numbers.Insert(1, 2);// inserts 11 at 1st index: after 10.
		
		foreach (var num in numbers)
			Console.WriteLine(num);
	}
}
 

1
2
3
4
 

using System;
using System.Collections.Generic;
					
public class Program
{
	public static void Main()
	{
		var numbers = new List(){ 1, 2, 3, 4, 5 };

		numbers.Remove(5); // removes 5 elements from a list
		
		numbers.RemoveAt(0); //removes the 3rd element (index starts from 0)
		
		foreach (var num in numbers)
			Console.WriteLine(num);
	}
}
 

2
3
4
 

using System;
using System.Collections.Generic;
					
public class Program
{
	public static void Main()
	{
		var Name = new List(){ "shubham", "batra", "abir", "mohit" };

		Console.WriteLine(Name.Contains("shubham"));
		Console.WriteLine(Name.Contains("batra"));
		Console.WriteLine(Name.Contains("shubham batra"));
		Console.WriteLine(Name.Contains("mohit"));

	}
}
 

True
True
False
True