example of zipping files to zip archive or extracting zipped files to a subdirectory

simpleCompExt.cs

using System; 
using System.IO;
using System.IO.Compression;

namespace ConsoleApplication {
    
    /*
    links to online source code listing: last updated 6/4/2019
      + https://gist.github.com/kyrathasoft/bdebc9ad97941e35abdde146bbf2d73b
      + https://pastebin.com/QYFZXEkq
    */

	class Program{
        
        static bool blnExit = false;
        static string startPath = @".\start";
        static string zipPath = @".\result.zip";
        static string extractPath = @".\extract";
 
 
		static void Main(string[] args){
            
  			ShowTitle();
            if(Init()){
                Console.WriteLine("\n Program initialization succeeded.");
                /* Because Init() succeeded, we know that:
                   (1) there's a /start subdir with at least one file
                   (2) there's NOT a result.zip file in the EXE's dir
                   (3) there's an /extract subdir that is empty
                */
                while(!blnExit){
                    BuildMenu();
                }
                
                Console.WriteLine("\n Program exits...\n");
            }
		}
        
        public static void BuildMenu(){
            Console.WriteLine("\n\n     Menu:");
            if(StartSubdirExistsWithOneOrMoreFiles() && ZipArchiveResultFileDoesntExist()){
                Console.WriteLine("       (Z)ip start subdir files to result.zip");
            }
            if(File.Exists("result.zip")){
                Console.WriteLine("      (E)xtract result.zip to .\\extract subdirectory");
                Console.WriteLine("       Extract (O)nly 'Program.cs to .\\extract sudirectory");
				Console.WriteLine("       (D)oes file 'MainForm.cs' exist in archive?");
				if(!ZipArchiveContainsThisFile("result.zip", "MyNameIs.txt")){
					Console.WriteLine("       D(y)namically add name/b-day to archive as entry 'MyNameIs.txt'");
				}
            }
			
            Console.WriteLine("       E(x)it Program");
            Console.Write("           Your selection > ");
            ConsoleKeyInfo cki = Console.ReadKey();
            switch(cki.Key){                    
                case ConsoleKey.Z:
                    ZipFile.CreateFromDirectory(startPath, zipPath);
                    SeeIfExtractDirExistsAndDeleteItsFiles();                
                    break;
				case ConsoleKey.D:
					if(ZipArchiveContainsThisFile("result.zip", "MainForm.cs")){
						Console.WriteLine("\n          Yes, 'MainForm.cs' is contained in result.zip.");
					}else{
						Console.WriteLine("\n          No, the program didn't find 'MainForm.cs' in result.zip.");
					}
					break;
                case ConsoleKey.E:
                    extractPath = SanitizeExtractPath(extractPath);
                    ZipFile.ExtractToDirectory(zipPath, extractPath);
                    SeeIfZippedArchiveExistsIfSoDelete();                
                    break;
                case ConsoleKey.O:
                    extractPath = SanitizeExtractPath(extractPath);
                    using (ZipArchive archive = ZipFile.OpenRead(zipPath)){
                        foreach (ZipArchiveEntry entry in archive.Entries){
                            string fname = entry.FullName;
                            if(fname.Contains("Program.cs")){
                                //Console.WriteLine("\n Found 'Program.cs'...");                            
                                string destinationPath = Path.GetFullPath(Path.Combine(extractPath, entry.FullName));                            
                                Console.WriteLine("\n Dest. path: {0}", destinationPath);
                                entry.ExtractToFile(destinationPath);
                            }
                        }
                    }                
                    break;
				case ConsoleKey.Y:
					using (FileStream zipToOpen = new FileStream(@".\result.zip", FileMode.Open))
					{
						using (ZipArchive archive = new ZipArchive(zipToOpen, ZipArchiveMode.Update))
						{
							ZipArchiveEntry readmeEntry = archive.CreateEntry("MyNameIs.txt");
							using (StreamWriter writer = new StreamWriter(readmeEntry.Open()))
							{
									writer.WriteLine("My name is Bryan Miller.");
									writer.WriteLine("The date: {0}", DateTime.Now.ToString());
							}
							Console.WriteLine("\n       Successfully added 'MyNameIs.txt' to 'result.zip'");
						}
					}				
					break;
                default:
                    blnExit = true;
                    break;
            }
        }
        
        public static bool Init(){
            bool success = false;
            if(SeeIfZippedArchiveExistsIfSoDelete()){
                if(SeeIfExtractDirExistsAndDeleteItsFiles()){
                    if(SeeIfStartDirExistsAndContainsFilesToBeZipped()){
                        success = true;
                    }
                }
            }
        
            return success;
        }
        
        public static string SanitizeExtractPath(string p){
            string result = p;
            
            result = Path.GetFullPath(result);
            if (!result.EndsWith(Path.DirectorySeparatorChar.ToString(), StringComparison.Ordinal)){
                result += Path.DirectorySeparatorChar;
            }
            
            return p;
        }
        
        public static bool ZipArchiveResultFileDoesntExist(){
            bool result = false;
            if(!File.Exists("result.zip")){ result = true;}
            return result;
        }
		
		public static bool ZipArchiveContainsThisFile(string _archive, string _filename_in_question){
				bool result = false;
				if(!File.Exists(_archive)){
					//control falls through; false is returned...
				}else{
					using(ZipArchive archive = ZipFile.OpenRead(_archive)){
						foreach(ZipArchiveEntry entry in archive.Entries){
							string filename = Path.GetFileName(entry.FullName);
							if(filename == _filename_in_question){
								result = true;
								break;
							}
						}
					}
				}
				return result;
		}
        
        public static bool StartSubdirExistsWithOneOrMoreFiles(){
            bool result = false;
            
            if(Directory.Exists(@".\start")){
                string[] files = Directory.GetFiles(@".\start", "*.*", SearchOption.TopDirectoryOnly);
                if(files.Length > 0){
                    result = true;
                }
            }
            
            return result;
        }
        
        public static bool SeeIfZippedArchiveExistsIfSoDelete(){
            bool success = false;
            if(File.Exists("result.zip")){
                try{
                    File.Delete("result.zip");
                    success = true;
                }catch{
                    Console.WriteLine("\n Unable to delete result.zip during initialization.");
                }
            }else{ success = true; }    
            return success;
        }
        
        public static bool SeeIfExtractDirExistsAndDeleteItsFiles(){
            bool success = false;
            if(Directory.Exists(@".\extract")){
                string[] files = Directory.GetFiles(@".\extract", "*.*", SearchOption.TopDirectoryOnly);
                if(files.Length > 0){
                    try{
                        for(int i=0; i < files.Length; i++){
                            File.Delete(files[i]);
                        }
                        success = true;
                    }catch{
                        Console.WriteLine("\n Unable to delete files in .\\extract during initialization.");
                    }
                }else{ success = true; }
            }else{
                Directory.CreateDirectory(@".\extract");
                success = true;
            }   
            return success;
        }
        
        public static bool SeeIfStartDirExistsAndContainsFilesToBeZipped(){
            bool success = false;
            if(!Directory.Exists(@".\start")){
                Console.WriteLine("\n Missing .\\start subdirectory with files to be zipped.");
                Console.WriteLine(" Program will terminate.\n");
            }else{
                //directory exists, but does it contain one or more files to be zipped?
                string[] files = Directory.GetFiles(@".\start", "*.*", SearchOption.TopDirectoryOnly);
                if(files.Length < 1){
                    Console.WriteLine("\n Subdirectory .\\start doesn't have any files to be zipped.");
                    Console.WriteLine(" Program will terminate.\n");
                }else{
					
                    success = true;
                }
            }            
            return success;
        }
        
        public static void ShowTitle(){
            Console.Clear();
            Console.ForegroundColor = ConsoleColor.Yellow;
            Console.WriteLine("\n running 'simple.exe'...");
            Console.ForegroundColor = ConsoleColor.Gray;
            Console.WriteLine(" kyrathasoft@gmail.com, 6/02/2019");
            Console.ForegroundColor = ConsoleColor.White;
        }
		  
    }
}