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C#: abstract

Manuel C# · Guide pratique

Indique une classe qui n’est pas instanciée directement ou un membre non implémenté requis pour un descendant non abstrait.

Exemple simple (Example.cs)

Enregistrez cet exemple séparément dans Example.cs. Exécutez-le indépendamment des autres exemples de cette page.

Example.cs:

// PROJECT-EXAMPLE
Shape shape = new Square();
System.Console.WriteLine(shape.Area);
abstract class Shape { public abstract int Area { get; } }
class Square : Shape { public override int Area => 4; }

Résultat:

4

Syntaxe

abstract class Base { public abstract void Run(); }

Exemple 1 : formulaire de base

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.IO;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;

public static class Program
{
    public static async Task Main(string[] args)
    {
        Entity entity = new Player("Archer");
        Console.WriteLine(entity.Describe());
        Console.WriteLine(entity.Code);
    }
}
public interface ILabel { string Label { get; } }
public abstract class Entity : ILabel
{
    private readonly string name;
    protected Entity(string name) { this.name = name; }
    protected string Name => name;
    internal int Code { get; set; } = 7;
    public virtual string Label => Name;
    public abstract string Describe();
}
public sealed class Player : Entity
{
    public Player(string name) : base(name) { }
    public override string Label => "Player: " + base.Label;
    public override string Describe() => Label;
}

Exemple 2 : une autre forme pratique

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.IO;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;

public static class Program
{
    public static async Task Main(string[] args)
    {
        Shape shape = new Square(3);
        Console.WriteLine(shape.Area);
    }
}
public abstract class Shape { public abstract int Area { get; } }
public sealed class Square(int side) : Shape { public override int Area => side * side; }

Source officielle : Microsoft Apprendre.