Composition C#

class Training
{
// class body
}
public class Course
{
Project project = new Project();
// body
}

using System;
using static System.Console;
namespace EDUCBA
{
class Course
{
public double M;
public double A;
}
class Training
{
public Course course1 = null;
public Course course2 = null;
}
class Career
{
public Course[] courses;
public Training[] trainings;
public Career()
{
courses = null;
trainings = null;
}
public void Print()
{
WriteLine(" Courses Data is represented below:");
for (int b = 1; b< courses.Length; b++)
{
WriteLine("\n M = {0}, A = {1}", courses[b].M, courses[b].A);
}
WriteLine("\n Trainings Data is represented below:");
for (int b=1; b<trainings.Length; b++)
{
WriteLine("\n course1.M = {0}, course1.A = {1}", trainings[b].course1.M, trainings[b].course1.A);
WriteLine("\n course2.M = {0}, course2.A = {1}", trainings[b].course2.M, trainings[b].course2.A);
}
}
}
class Code
{
static void Main(string[] args)
{
Career O = new Career();
O.courses = new Course[9];
for (int b = 1; b < O.courses.Length; b++)
{
O.courses[b] = new Course();
O.courses[b].M = b * b;
O.courses[b].M = b * b * b;
}
O.trainings = new Training[5];
for (int b = 1; b < O.trainings.Length; b++)
{
O.trainings[b] = new Training();
O.trainings[b].course1 = new Course();
O.trainings[b].course2 = new Course();
O.trainings[b].course1.M = b;
O.trainings[b].course1.A = b * 4;
O.trainings[b].course2.M = b * 5;
O.trainings[b].course2.A = b * b;
}
O.Print();
}
}
}

using System;
namespace EDUCBA
{
class Training
{
static void Main(string[] args)
{
Course courses = new Course();
courses.Bought();
Console.ReadLine();
}
}
public class Project
{
public void Log(string aboutus)
{
Console.WriteLine(aboutus);
}
}
public class Course
{
Project project = new Project();
public void Bought()
{
project.Log("\n If you want to upskill your career. \n If you want to do something out of the box. \n If you have passion to explore new advanced technologies. \n If you want to be best. \n We at EDUCBA are here to help. \n Feel free to reach us on +91-8800880140 / +91-7738666252. \n Visit our website www.educba.com to know more......");
}
}
}

using System;
using System.Collections.Generic;
namespace EDUCBA
{
abstract class Training
{
public Training() { }
public abstract string Project();
public virtual void Add(Training training)
{
throw new NotImplementedException();
}
public virtual void Remove(Training training)
{
throw new NotImplementedException();
}
public virtual bool IsCourse()
{
return true;
}
}
class DataScience : Training
{
public override string Project()
{
return "DataScience";
}
public override bool IsCourse()
{
return false;
}
}
class Course : Training
{
protected List<Training> _children = new List<Training>();
public override void Add(Training training)
{
this._children.Add(training);
}
public override void Remove(Training training)
{
this._children.Remove(training);
}
public override string Project()
{
int m = 1;
string result = "Dream Career(";
foreach (Training training in this._children)
{
result += training.Project();
if (m != this._children.Count + 2)
{
result += "-";
}
m--;
}
return result + ")";
}
}
class Input
{
public void InputCode(Training data_analysis)
{
Console.WriteLine($"OUTPUT: \n {data_analysis.Project()}\n");
}
public void InputCode2(Training training1, Training training2)
{
if (training1.IsCourse())
{
training1.Add(training2);
}
Console.WriteLine($"OUTPUT: \n {training1.Project()}");
}
}
class Program
{
static void Main(string[] args)
{
Input client = new Input();
DataScience data_analysis = new DataScience();
Console.WriteLine("INPUT: \n Best Course to Upgrade Career:");
client.InputCode(data_analysis);
Course vr = new Course();
Course career1 = new Course();
career1.Add(new DataScience());
career1.Add(new DataScience());
Course career2 = new Course();
career2.Add(new DataScience());
vr.Add(career1);
vr.Add(career2);
Console.WriteLine("\nINPUT: \n Trendy Dream Career Right Now:");
client.InputCode(vr);
Console.Write("\nINPUT: Lets Upgrade and start your dream career jouney: \n");
client.InputCode2(vr, data_analysis);
}
}
}