क्लोज़र और कैप्चर किए गए वैरिएबल

using System;

public class Program
{
    public static void Main()
    {
        int factor = 3;
        int Scale(int n) => n * factor; // captures factor

        Console.WriteLine(Scale(5));
        Console.WriteLine(Scale(10));
    }
}

using System;

public class Program
{
    public static void Main()
    {
        int offset = 10;
        int Add(int n) => n + offset;

        Console.WriteLine(Add(1)); // 11
        offset = 100;
        Console.WriteLine(Add(1)); // 101 - sees updated offset
    }
}

using System;

public class Program
{
    public static void Main()
    {
        int count = 0;
        void Tick() => count++;

        Tick(); Tick(); Tick();
        Console.WriteLine(count); // 3
    }
}

using System;

public class Program
{
    static Func<int> MakeCounter()
    {
        int count = 0;
        return () => ++count; // captures count
    }

    public static void Main()
    {
        var next = MakeCounter();
        Console.WriteLine(next());
        Console.WriteLine(next());
        Console.WriteLine(next());
    }
}

using System;

public class Program
{
    static Func<int> MakeCounter()
    {
        int count = 0;
        return () => ++count;
    }

    public static void Main()
    {
        var a = MakeCounter();
        var b = MakeCounter();
        Console.WriteLine(a()); // 1
        Console.WriteLine(a()); // 2
        Console.WriteLine(b()); // 1 - separate state
    }
}

using System;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {
        var actions = new List<Action>();
        foreach (var i in new[] { 1, 2, 3 })
            actions.Add(() => Console.WriteLine(i));

        foreach (var act in actions) act(); // prints 1, 2, 3
    }
}

using System;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {
        var actions = new List<Action>();
        for (int i = 0; i < 3; i++)
        {
            int copy = i; // fresh local each iteration
            actions.Add(() => Console.WriteLine(copy));
        }
        foreach (var act in actions) act(); // prints 0, 1, 2
    }
}

using System;

public class Program
{
    public static void Main()
    {
        string message = "first";
        Action print = () => Console.WriteLine(message);

        print();          // first
        message = "second";
        print();          // second
    }
}

using System;

public class Program
{
    static Func<double, double> MakeDiscount(double rate)
        => price => price * (1 - rate);

    public static void Main()
    {
        var tenOff = MakeDiscount(0.10);
        var halfOff = MakeDiscount(0.50);
        Console.WriteLine(tenOff(100));
        Console.WriteLine(halfOff(100));
    }
}

using System;

public class Program
{
    static Func<int> MakeStepper(int step)
    {
        int current = 0;
        return () => { current += step; return current; }; // captures current and step
    }

    public static void Main()
    {
        var byTwos = MakeStepper(2);
        var byTens = MakeStepper(10);
        Console.WriteLine(byTwos()); // 2
        Console.WriteLine(byTwos()); // 4
        Console.WriteLine(byTens()); // 10 - separate state
    }
}