c# lists of a list code example

Example 1: c# lists

// ------------------- How to initialize Lists? --------------------- //

using System.Collections.Generic   // You need to include this!

// 1º Method
var myList = new List<int>();
//OR
List<int> myList = new List<int>();
  

// 2º Method
List<int> myList = new List<int>() {2, 5, 9, 12};


// 3º Method
string myString = "Hello"
List<char> myList = new List<char>(myString);  // Creates a list of characters from that string 
//OR
var myFirstList = new List<int>() {9, 2, 4, 3, 2, 1};
var mySecondList = new List<int>(myFirstList);   // Copy a list to a second list 




// -------- How to dynamically change the List of elements? --------- //

// Use the Add or Insert method to add one element
myList.Add(4);  

myList.Insert(0,3)  // Insert element "3" in position "0"
  

// Use the AddRange method to add many elements (you can use an array or
// list, for passing the values)
myList.AddRange(new int[3] {3, 5, 5, 9, 2}); 


// Use the Remove method to eliminate specific elements
for (int i = 0; i < myList.Count; i++)   // Use a for loop to remove 
{										// repeated elements
  if ( myList[i] == 5)
  {
  	myList.Remove(myList[i]);
    i--;
  }
}

// Use the Clear method to remove all elements from the list
myList.Clear();




// ---------------- How to create a List of Lists? ------------------ //

List<List<int>> myList = new List<List<int>>(){
	new List<int>() {1,2,3},
	new List<int>() {4,5,6},
	new List<int>() {7,8,9}
};
		
Console.WriteLine(myList.ElementAt(0).ElementAt(1)); // You get "2"

Example 2: syntax list C#

List<int> primeNumbers = new List<int>();
primeNumbers.Add(1); // adding elements using add() method
primeNumbers.Add(3);
primeNumbers.Add(5);
primeNumbers.Add(7);

var cities = new List<string>();
cities.Add("New York");
cities.Add("London");
cities.Add("Mumbai");
cities.Add("Chicago");
cities.Add(null);// nulls are allowed for reference type list

//adding elements using collection-initializer syntax
var bigCities = new List<string>()
                    {
                        "New York",
                        "London",
                        "Mumbai",
                        "Chicago"                    
                    };