using System;using System.Collections;using System.Collections.Generic;using System.Collections.Specialized;using System.Diagnostics;using System.IO;using System.Linq;using System.Runtime.InteropServices;using System.Text;using System.Threading.Tasks;using System.Runtime.Serialization.Formatters.Binary;using System.Threading;using System.Diagnostics.CodeAnalysis;namespace ConsoleApp1{ class Program { //out도 call by reference다. //ref와 다른점은 값을 할당만 가능, 무조건 사용해야됨 static void Swap(ref int a, ref int b) { int tmp = a; a = b; b = tmp; } static void Main(string[] args) { int a = 1; int b = 2; Swap(ref a, ref b); Console.WriteLine("a = {0}, b = {1}", a, b); } }}