https://www.csharpstudy.com/

https://www.youtube.com/watch?v=NZ0csWCxD3g&list=PLiNvMfa_Y5hfgpgd3hgXdHACCZuIEozjL

1. C# 데이타 타입
2. C# yield 문
3. C# 구조체 (struct)
4. C# 클래스 (class) 개념과 사용법
5. C# 이벤트(event) 활용 사례

C# yield 문

yield return은 데이터를 하나씩 리턴한다.

yield break는 메소드를 끝낸다. (break 는 가장 가까운 반복문을 끝낸다.)

private void main()
{
    foreach (var score in GetScores())
    {
        Console.WriteLine(score);
    }
}

private IEnumerable<int> GetScores()  // foreach 를 하나씩 돈다.
{
    int[] scores = new int[] { 10, 20, 30, 40, 50 };

    for (int i = 0; i < scores.Length; i++)
    {
        if (scores[i] == 30)
        {            
            yield break; // 메소드를 끝냄.
            // break // 가장 가까운 반복문을 끝냄.
        }
        yield return scores[i];
        Console.WriteLine(i + " : Done");
    }
}

C# 구조체 (struct)

https://docs.microsoft.com/ko-kr/dotnet/csharp/language-reference/builtin-types/struct

public struct Coords
{
    public Coords(double x, double y)
    {
        X = x;
        Y = y;
    }

    public double X { get; }
    public double Y { get; }

    public override string ToString() => $"({X}, {Y})";
}

C# 클래스 (class) 개념과 사용법

public class Brick
{
    // 필드 (데이타)
    private int width;
    private int height;
    private int depth;
    private Color color;

    // 생성자 (Constructor)
    public Brick()
    {
        width = 10;
        height = 10;
        depth = 5;
        color = Color.Gray;
    }

    // Constructor that takes four arguments:
    public Brick(int width, int height, int depth, Color color)
    {
        this.width = width;
        this.height = height;
        this.depth = depth;
        this.color = color;
    }

    // 속성 (Property)
    public int Width
    {
        get { return this.width; }
        set
        {
            if (value > 0)
            {
                this.width = value;
            }
        }
    }

    public Color Color
    {
        get { return this.color; }
    }

    public int Volume
    {
        get { return width * height * depth; }
    }

    // 메서드 (Method)
    public void MakeBrick()
    {
        // Event Fire
        if (ProcessStarted != null)
        {
            ProcessStarted(this, EventArgs.Empty);
        }
        Step1();
        Step2();
        Step3();
        if (ProcessCompleted != null)
        {
            ProcessCompleted(this, EventArgs.Empty);
        }
    }

    private void Step1()
    {
        Console.WriteLine("Step #1");
    }

    private void Step2()
    {
        Console.WriteLine("Step #2");
    }

    private void Step3()
    {
        Console.WriteLine("Step #3");
    }

    // 이벤트
    // 클래스 내부에서 일이 일어났을 때 외부에 알리는 역할
    public event EventHandler ProcessStarted;
    public event EventHandler ProcessCompleted;
}

public MainWindow()
{
    Brick br = new Brick();
    Brick br2 = new Brick(50, 100, 20, Color.Gray);

    int w = br2.Width;
    br2.Width = -1;
    Color c = br2.Color;
    int v = br2.Volume;

    br2.ProcessStarted += Br2_ProcessStarted;
    br2.ProcessCompleted += Br2_ProcessCompleted;
    br2.MakeBrick();
}

private void Br2_ProcessStarted(object sender, EventArgs e)
{
    Console.WriteLine("Process Started");
}

private void Br2_ProcessCompleted(object sender, EventArgs e)
{
    Console.WriteLine("Process Completed");
}

C# 이벤트(event) 활용 사례

// 방법: 스레드로부터 안전한 호출을 Windows Forms 컨트롤 만들기
https://docs.microsoft.com/ko-kr/dotnet/desktop/winforms/controls/how-to-make-thread-safe-calls-to-windows-forms-controls?view=netframeworkdesktop-4.8

namespace FormsEventExercise
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnCopy_Click(object sender, EventArgs e)
        {
            Thread t = new Thread(CopyFile);
            t.Start();
        }

        private void CopyFile()
        {
            FileManager fm = new FileManager();

            fm.InProgress += Fm_InProgress;
            fm.InProgress += Fm_InProgress2;
            fm.Copy("src.mp4", "destfile.mp4");
        }

        private void Fm_InProgress2(object sender, double e)
        {
            Debug.WriteLine("Progress {0}", e);
        }

        private void Fm_InProgress(object sender, double e)
        {
            // UI 쓰레드인지 확인
            if (InvokeRequired)
            {
                Invoke(new EventHandler<double>(Fm_InProgress), sender, e);
            }
            else
            {
                this.progressBar1.Value = (int)e;
                this.lblPct.Text = string.Format("{0} %", (int)e);
            }
        }
    }
}

namespace FormsEventExercise
{
    public class FileManager
    {
        public event EventHandler<double> InProgress;

        public void Copy(string srcfile, string destfile)
        {
            byte[] buffer = new byte[1024];
            int pos = 0;

            // 파일 사이즈
            var fi = new FileInfo(srcfile);
            var fileSize = fi.Length;

            // 파일 복사
            using (BinaryReader rd = new BinaryReader(File.Open(srcfile, FileMode.Open)))
            using (BinaryWriter wr = new BinaryWriter(File.Open(destfile, FileMode.Create)))
            {
                while (pos < fileSize)
                {
                    int count = rd.Read(buffer, 0, buffer.Length);
                    wr.Write(buffer, 0, count);
                    pos += count;

                    double pct = (pos / (double)fileSize) * 100;

                    if (InProgress != null)
                    {
                        InProgress(this, pct);
                    }
                }
            }
        }
    }
}

C# 데이타 타입

bool b = true;

// signed integer
short sh = 100;
int i = 100;
long l = 10000L;
            
// unsigned integer
ushort us = 111;
uint ui = 110U;
ulong ul = 1000UL;

float f = 3.14f; // 32bit
double d = 3.141592d; // 64bit
decimal dd = 3.14M; // 128bit
                        
char ch = '한'; // 16bit Unicode

byte by = 0x46; // 8bit

// nullable type
int? ix = null;
if (ix == null)
{
    Console.WriteLine("ix is null");
}
else
{
    Console.WriteLine(ix.Value);
}

string s = "Hello";
object o = null;