Answers for "c# class list"

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"

to list c#

var arr = new int[] {1, 2, 3};
List<int> list = arr.ToList();

c# list of different objects

Or is there a better/different way to do this?

If your objects descend from a common class, then you can store them in the same collection. In order to do anything useful with your objects without throwing away type safety, you'd need to implement the visitor pattern:

public interface EntityVisitor
{
    void Visit(Arc arc);
    void Visit(Line line);
}

public abstract class Entity
{
    public abstract void Accept(EntityVisitor visitor);
}

public class Arc : Entity
{
    protected double startx;
    protected double starty;
    protected double endx;
    protected double endy;
    protected double radius;

    public override void Accept(EntityVisitor visitor)
    {
        visitor.Visit(this);
    }
}

public class Line : Entity
{
    protected double startx;
    protected double starty;
    protected double endx;
    protected double endy;
    protected double length;

    public override void Accept(EntityVisitor visitor)
    {
        visitor.Visit(this);
    }
}
Once that's in place, you create an instance of EntityVisitor whenever you need to do something useful with your list:

class EntityTypeCounter : EntityVisitor
{
    public int TotalLines { get; private set; }
    public int TotalArcs { get; private set; }

    #region EntityVisitor Members

    public void Visit(Arc arc) { TotalArcs++; }
    public void Visit(Line line) { TotalLines++; }

    #endregion
}

class Program
{
    static void Main(string[] args)
    {
        Entity[] entities = new Entity[] { new Arc(), new Line(), new Arc(), new Arc(), new Line() };
        EntityTypeCounter counter = entities.Aggregate(
            new EntityTypeCounter(),
            (acc, item) => { item.Accept(acc); return acc; });

        Console.WriteLine("TotalLines: {0}", counter.TotalLines);
        Console.WriteLine("TotalArcs: {0}", counter.TotalArcs);
    }
}
And for what its worth, if your open to trying new languages, then F#'s tagged unions + pattern matching are a handy alternative to the visitor pattern.