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CSharp · Console

/Program.cs

using System;

class Singleton
{
	protected Singleton() { }
	private static Singleton _singleton;

	public static Singleton Instance 
	{
		get { 
			if (_singleton == null)
			{
				_singleton = new Singleton();
			}
			return _singleton;
		}
	}       

	public int CodigoSingleton { get; set; }
}

public class Program
{
	public static void Main()
	{
		Singleton singleton0 = Singleton.Instance;
        Singleton singleton1 = Singleton.Instance; // mesma instância de singleton0
		
		singleton0.CodigoSingleton = 5;
		System.Console.WriteLine(singleton1.CodigoSingleton);
		
	}
}