A very basic example of an IoC Container

ioCContainer

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var container = new Container();
        container.Bind<ICar, Car>();
        container.Bind<IEngine, Engine>();
        container.Bind<IStarterMotor, StarterMotor>();
    
        var car = container.Resolve<ICar>();
        car.StartEngine();

        Console.ReadLine();
    }
}

class Car : ICar
{
    public Car(IEngine engine)
    {
        Console.WriteLine("Car Created!");
    }

    public void StartEngine()
    {
        Console.WriteLine("-- Engine Started --");
    }
}

class Engine : IEngine
{
    public Engine(IStarterMotor startMotor)
    {
        Console.WriteLine("Engine Created!");
    }
}

class StarterMotor : IStarterMotor
{
    public StarterMotor()
    {
        Console.WriteLine("Starter Motor Created!");
    }
}

internal interface ICar { void StartEngine();}
internal interface IStarterMotor { }
internal interface IEngine { }

/// <summary>
/// IoC Container
/// </summary>
class Container
{
    private readonly Dictionary<Type, Func<object>> _providers;

    public Container()
    {
        _providers = new Dictionary<Type, Func<object>>();
    }

    public void Bind<TInterface, TConcrete>() where TConcrete : TInterface
    {
        _providers[typeof(TInterface)] = () => Resolve(typeof(TConcrete));
    }

    public T Resolve<T>()
    {
        return (T)_providers[typeof(T)]();
    }

    private object Resolve(Type type)
    {
        var constructor = type.GetConstructors().SingleOrDefault();
        var parametersInfo = constructor.GetParameters();
        var parameters = new List<object>();

        foreach (var parameterInfo in parametersInfo)
        {
            parameters.Add(_providers[parameterInfo.ParameterType]());
        }      

        return constructor.Invoke(parameters.ToArray());
    }
}