Getting Started DI example from https://autofac.readthedocs.io/en/latest/getting-started/index.html

AutoFacGettingStarted.cs

using System;
using Autofac;

namespace DemoApp
{
  // This interface helps decouple the concept of
  // "writing output" from the Console class. We
  // don't really "care" how the Write operation
  // happens, just that we can write.
  public interface IOutput
  {
    void Write(string content);
  }

  // This implementation of the IOutput interface
  // is actually how we write to the Console. Technically
  // we could also implement IOutput to write to Debug
  // or Trace... or anywhere else.
  public class ConsoleOutput : IOutput
  {
    public void Write(string content)
    {
      Console.WriteLine(content);
    }
  }

  // This interface decouples the notion of writing
  // a date from the actual mechanism that performs
  // the writing. Like with IOutput, the process
  // is abstracted behind an interface.
  public interface IDateWriter
  {
    void WriteDate();
  }

  // This TodayWriter is where it all comes together.
  // Notice it takes a constructor parameter of type
  // IOutput - that lets the writer write to anywhere
  // based on the implementation. Further, it implements
  // WriteDate such that today's date is written out;
  // you could have one that writes in a different format
  // or a different date.
  public class TodayWriter : IDateWriter
  {
    private IOutput _output;
    public TodayWriter(IOutput output)
    {
      this._output = output;
    }

    public void WriteDate()
    {
      this._output.Write(DateTime.Today.ToShortDateString());
    }
  }

  public class Program
  {
    private static IContainer Container { get; set; }

    static void Main(string[] args)
    {
      var builder = new ContainerBuilder();
      builder.RegisterType<ConsoleOutput>().As<IOutput>();
      builder.RegisterType<TodayWriter>().As<IDateWriter>();
      Container = builder.Build();

      // The WriteDate method is where we'll make use
      // of our dependency injection. We'll define that
      // in a bit.
      WriteDate();
    }
  }
  
  public static void WriteDate()
  {
    // Create the scope, resolve your IDateWriter,
    // use it, then dispose of the scope.
    using (var scope = Container.BeginLifetimeScope())
    {
      var writer = scope.Resolve<IDateWriter>();
      writer.WriteDate();
    }
  }
}