Interfaces and Abstractions

Interface Intro

An interface names behavior that a class promises to provide.

Interface Intro

InterfaceIntro.cs 
using System;

interface ILabel
{
    string Label();
}

class NameTag : ILabel
{
    private readonly string name;

    public NameTag(string name)
    {
        this.name = name;
    }

    public string Label()
    {
        return "tag:" + name;
    }
}

class Program
{
    static void Main()
    {
        string name = ;
        NameTag tag = new NameTag(name);
        string label = tag.Label();

        Console.WriteLine($"name={name}");
        Console.WriteLine($"label={label}");
    }
}

using System;

interface ILabel
{
    string Label();
}

class NameTag : ILabel
{
    private readonly string name;

    public NameTag(string name)
    {
        this.name = name;
    }

    public string Label()
    {
        return "tag:" + name;
    }
}

class Program
{
    static void Main()
    {
        string name = ;
        NameTag tag = new NameTag(name);
        string label = tag.Label();

        Console.WriteLine($"name={name}");
        Console.WriteLine($"label={label}");
    }
}

using System;

interface ILabel
{
    string Label();
}

class NameTag : ILabel
{
    private readonly string name;

    public NameTag(string name)
    {
        this.name = name;
    }

    public string Label()
    {
        return "tag:" + name;
    }
}

class Program
{
    static void Main()
    {
        string name = ;
        NameTag tag = new NameTag(name);
        string label = tag.Label();

        Console.WriteLine($"name={name}");
        Console.WriteLine($"label={label}");
    }
}
interface An interface describes methods or properties without storing object state.