Csharp/C Sharp by API/System.Collections.Generic/List

extends List

  
using System;
using System.Collections.Generic;
using System.Text;
public static class VectorDelegates {
    public static int Compare(Vector x, Vector y) {
        if (x.R > y.R) {
            return 1;
        } else if (x.R < y.R) {
            return -1;
        }
        return 0;
    }
    public static bool TopRightQuadrant(Vector target) {
        if (target.Theta >= 0.0 && target.Theta <= 90.0) {
            return true;
        } else {
            return false;
        }
    }
}
public class Vectors : List<Vector> {
    public Vectors() {
    }
    public Vectors(IEnumerable<Vector> initialItems) {
        foreach (Vector vector in initialItems) {
            Add(vector);
        }
    }
    public string Sum() {
        StringBuilder sb = new StringBuilder();
        Vector currentPoint = new Vector(0.0, 0.0);
        sb.Append("origin");
        foreach (Vector vector in this) {
            sb.AppendFormat(" + {0}", vector);
            currentPoint += vector;
        }
        sb.AppendFormat(" = {0}", currentPoint);
        return sb.ToString();
    }
}
public class Vector {
    public double? R = null;
    public double? Theta = null;
    public double? ThetaRadians {
        get {
            return (Theta * Math.PI / 180.0);
        }
    }
    public Vector(double? r, double? theta) {
        if (r < 0) {
            r = -r;
            theta += 180;
        }
        theta = theta % 360;
        R = r;
        Theta = theta;
    }
    public static Vector operator +(Vector op1, Vector op2) {
        try {
            double newX = op1.R.Value * Math.Sin(op1.ThetaRadians.Value)
               + op2.R.Value * Math.Sin(op2.ThetaRadians.Value);
            double newY = op1.R.Value * Math.Cos(op1.ThetaRadians.Value)
               + op2.R.Value * Math.Cos(op2.ThetaRadians.Value);
            double newR = Math.Sqrt(newX * newX + newY * newY);
            double newTheta = Math.Atan2(newX, newY) * 180.0 / Math.PI;
            return new Vector(newR, newTheta);
        } catch {
            return new Vector(null, null);
        }
    }
    public static Vector operator -(Vector op1) {
        return new Vector(-op1.R, op1.Theta);
    }
    public static Vector operator -(Vector op1, Vector op2) {
        return op1 + (-op2);
    }
    public override string ToString() {
        string rString = R.HasValue ? R.ToString() : "null";
        string thetaString = Theta.HasValue ? Theta.ToString() : "null";
        return string.Format("({0}, {1})", rString, thetaString);
    }
}
class Program {
    static void Main(string[] args) {
        Vectors route = new Vectors();
        route.Add(new Vector(2.0, 90.0));
        route.Add(new Vector(1.0, 180.0));
        route.Add(new Vector(0.5, 45.0));
        route.Add(new Vector(2.5, 315.0));
        Console.WriteLine(route.Sum());
        Comparison<Vector> sorter = new Comparison<Vector>(VectorDelegates.rupare);
        route.Sort(sorter);
        Console.WriteLine(route.Sum());
        Predicate<Vector> searcher = new Predicate<Vector>(VectorDelegates.TopRightQuadrant);
        Vectors topRightQuadrantRoute = new Vectors(route.FindAll(searcher));
        Console.WriteLine(topRightQuadrantRoute.Sum());
    }
}

List.Add

 
using System;
using System.Collections.Generic;
public class MainClass
{
    static void Main() {
        List<int> intList = new List<int>();
        intList.Add( 1 );
        intList.Add( 2 );
        intList.Add( 3 );
        intList.Add( 4 );
        foreach( int n in CreateReverseIterator(intList) ) {
            Console.WriteLine( n );
        }
    }
    static IEnumerable<T> CreateReverseIterator<T>( IList<T> list ) {
        int count = list.Count;
        for( int i = count-1; i >= 0; --i ) {
            yield return list[i];
        }
    }
}

List.AsReadOnly()

  
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Text;
public class MainClass
{
    public static void Main()
    {
        List<int> intList = new List<int>(new int[] { 3, 5, 15, 1003, 25 });
        ReadOnlyCollection<int> roList = intList.AsReadOnly();
    }
}

List.Capacity

 
using System;  
using System.Collections.Generic;  
  
class MainClass {  
  public static void Main() {  
    List<char> lst = new List<char>();  
      
    Console.WriteLine("Initial number of elements: " +  
                       lst.Count);  
  
    Console.WriteLine();  
  
    Console.WriteLine("Adding 6 elements");  
    lst.Add("C");  
    lst.Add("A");  
    lst.Add("E");  
    lst.Add("B");  
    lst.Add("D");  
    lst.Add("F");  
  
    Console.WriteLine("Number of elements: " +  
                       lst.Count);  
  
     Console.WriteLine("Adding 20 more elements");  
    // Add enough elements to force lst to grow.  
    for(int i=0; i < 20; i++)  
      lst.Add((char)("a" + i));  
    Console.WriteLine("Current capacity: " +  
                       lst.Capacity);  
    Console.WriteLine("Number of elements after adding 20: " +  
                       lst.Count);  
    Console.Write("Contents: ");  
    foreach(char c in lst)  
      Console.Write(c + " ");  
    Console.WriteLine("\n");  
  }
}

List.ConvertAll

  

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Text;
public class MainClass
{
    public static void Main()
    {
        List<string> stringList1 = new List<string>(new string[] { "99", "182", "15" });
        List<int> intList1 = stringList1.ConvertAll<int>(Convert.ToInt32);
    }
}

List.Count

 
  
using System;  
using System.Collections.Generic;  
  
class MainClass {  
  public static void Main() {  
    List<char> lst = new List<char>();  
      
    Console.WriteLine("Initial number of elements: " +  
                       lst.Count);  
  
    Console.WriteLine();  
  
    Console.WriteLine("Adding 6 elements");  
    lst.Add("C");  
    lst.Add("A");  
    lst.Add("E");  
    lst.Add("B");  
    lst.Add("D");  
    lst.Add("F");  
  
    Console.WriteLine("Number of elements: " +  
                       lst.Count);  
  
    Console.Write("Current contents: ");  
    for(int i=0; i < lst.Count; i++)  
      Console.Write(lst[i] + " ");  
    Console.WriteLine("\n");  
  }
}

List.ForEach

  
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Text;
public class MainClass
{
    public static void Main()
    {
        List<int> intList = new List<int>(new int[] { 3, 5, 15, 1003, 25 });
        
        intList.ForEach(delegate(int x) { Console.WriteLine(x); });
    }
}

List.Remove()

 
using System;  
using System.Collections.Generic;  
  
class MainClass {  
  public static void Main() {  
    List<char> lst = new List<char>();  
      
    Console.WriteLine("Initial number of elements: " +  
                       lst.Count);  
  
    Console.WriteLine();  
  
    Console.WriteLine("Adding 6 elements");  
    lst.Add("C");  
    lst.Add("A");  
    lst.Add("E");  
    lst.Add("B");  
    lst.Add("D");  
    lst.Add("F");  
  
    Console.WriteLine("Number of elements: " +  
                       lst.Count);  
  
    Console.WriteLine("Removing 2 elements");  
    // Remove elements from the array list.  
    lst.Remove("F");  
    lst.Remove("A");  
  
    Console.WriteLine("Number of elements: " +  
                       lst.Count);  
  }
}

new List<T>()

 
using System.Collections.Generic;
using System;

class MainClass
{
    public static void Main(string[] args)
    {
        List<MyClass> list = new List<MyClass>();
        list.Add(new MyClass());
        MyClass ass2 = list[0];
        Console.WriteLine("\nFound in list: {0}", ass2);
    }
}
class MyClass {
    
   public override string ToString(){
    
      return "my class";
   }
    
}