선택적/이름 지정 매개변수, ref/out/in(기초)

강의 개요

선택적 매개 변수

using System;

public static class Notifier
{
  // Optional parameter: suffix has a default value
  public static void Notify(string message, string suffix = "!")
  {
    Console.WriteLine(message + suffix);
  }
}

public class Program
{
  public static void Main(string[] args)
  {
    Notifier.Notify("Saved");          // uses "!"
    Notifier.Notify("Warning", "!!");  // overrides default
  }
}

이름 있는 인수

using System;

public static class Greeter
{
  public static void Greet(string name, string prefix, int repeat)
  {
    for (int i = 0; i < repeat; i = i + 1)
    {
      Console.WriteLine(prefix + " " + name);
    }
  }
}

public class Program
{
  public static void Main(string[] args)
  {
    // Named args improve readability and allow reordering at call site
    Greeter.Greet(name: "Ada", prefix: "Hello", repeat: 2);
    Greeter.Greet(repeat: 1, name: "Alan", prefix: "Hi");
  }
}

ref 매개 변수

using System;

public static class RefDemo
{
  public static void Increment(ref int n)
  {
    n = n + 1; // modifies caller's variable
  }
}

public class Program
{
  public static void Main(string[] args)
  {
    int value = 5;           // must be assigned before passing by ref
    RefDemo.Increment(ref value);
    Console.WriteLine("value = " + value); // 6
  }
}

out 매개 변수

using System;

public static class OutDemo
{
  public static bool TryDivide(int a, int b, out int result)
  {
    if (b == 0)
    {
      result = 0;   // out must be assigned before return
      return false;
    }
    result = a / b;
    return true;
  }
}

public class Program
{
  public static void Main(string[] args)
  {
    int r; // not required to be assigned before passing as out
    bool ok = OutDemo.TryDivide(9, 0, out r);
    Console.WriteLine("ok=" + ok + " r=" + r);
  }
}

"in"에 관하여(C# 6)

ref와 out의 기본

복습