Книга: C# 2008 Programmer

Working with Directories

Working with Directories

The .NET Framework class library provides two classes for manipulating directories:

? DirectoryInfo class

? Directory class

The DirectoryInfo class exposes instance methods for dealing with directories while the Directory class exposes static methods.

The DirectoryInfo class provides various instance methods and properties for creating, deleting, and manipulating directories. The following table describes some of the common methods you can use to programmatically manipulate directories.

And here are some of the common properties:

To see how to use the DirectoryInfo class, consider the following example:

static void Main(string[] args) {
 string path = @"C:My Folder";
 DirectoryInfo di = new DirectoryInfo(path);
 try {
  //---if directory does not exists---
  if (!di.Exists) {
   //---create the directory---
   di.Create(); //---c:My Folder---
   //---creates subdirectories---
   di.CreateSubdirectory("Subdir1"); //---c:My FolderSubdir1---
   di.CreateSubdirectory("Subdir2"); //---c:My FolderSubdir2---
  }
  //---print out some info about the directory---
  Console.WriteLine(di.FullName);
  Console.WriteLine(di.CreationTime);
  //---get and print all the subdirectories---
  DirectoryInfo[] subDirs = di.GetDirectories();
  foreach (DirectoryInfo subDir in subDirs)
   Console.WriteLine(subDir.FullName);
  //---get the parent of C:My folder---
  DirectoryInfo parent = di.Parent;
  if (parent.Exists) {
   //---prints out C:---
   Console.WriteLine(parent.FullName);
  }
  //---creates C:My FolderSubdir3---
  DirectoryInfo newlyCreatedFolder =
   di.CreateSubdirectory("Subdir3");
  //---deletes C:My FolderSubdir3---
  newlyCreatedFolder.Delete();
 } catch (IOException ex) {
  Console.WriteLine(ex.Message);
 } catch (Exception ex) {
  Console.WriteLine(ex.Message);
 }
 Console.ReadLine();
}

In this example, you first create an instance of the DirectoryInfo class by instantiating it with a path (C:My Folder). You check if the path exists by using the Exist property. If it does not exist, you create the folder (C:My Folder) and then create two subdirectories underneath it (Subdir1 and Subdir2).

Next, you print out the full pathname (using the FullName property) of the folder and its creation date (using the CreationTime property). You then get all the subdirectories under C:My Folder and display their full pathnames. You can get the parent of the C:My Folder using the Parent property.

Finally, you create a subdirectory named Subdir3 under C:My Folder and pass a reference to the newly created subdirectory to the newlyCreatedFolder object. You then delete the folder, using the Delete() method.

The Directory class is similar to DirectoryInfo class. The key difference between is that Directory exposes static members instead of instance members. The Directory class also exposes only methods — no properties. Some of the commonly used methods are described in the following table.

Here's the previous program using the DirectoryInfo class rewritten to use the Directory class:

static void Main(string[] args) {
 string path = @"C:My Folder";
 try {
  //---if directory does not exists---
  if (!Directory.Exists(path)) {
   //---create the directory---
   Directory.CreateDirectory(path);
   //---set the current directory to C:My Folder---
   Directory.SetCurrentDirectory(path);
   //---creates subdirectories---
   //---c:My FolderSubdir1---
   Directory.CreateDirectory("Subdir1");
   //---c:My FolderSubdir2---
   Directory.CreateDirectory("Subdir2");
  }
  //---set the current directory to C:My Folder---
  Directory.SetCurrentDirectory(path);
  //---print out some info about the directory---
  Console.WriteLine(Directory.GetCurrentDirectory());
  Console.WriteLine(Directory.GetCreationTime(path));
  //---get and print all the subdirectories---
  string[] subDirs = Directory.GetDirectories(path);
  foreach (string subDir in subDirs)
   Console.WriteLine(subDir);
  //---get the parent of C:My folder---
  DirectoryInfo parent = Directory.GetParent(path);
  if (parent.Exists) {
   //---prints out C:---
   Console.WriteLine(parent.FullName);
  }
  //---creates C:My FolderSubdir3---
  Directory.CreateDirectory("Subdir3");
  //---deletes C:My FolderSubdir3---
  Directory.Delete("Subdir3");
 } catch (IOException ex) {
  Console.WriteLine(ex.Message);
 } catch (Exception ex) {
  Console.WriteLine(ex.Message);
 }
 Console.ReadLine();
}

As you can see, most of the methods in the Directory class require you to specify the directory you are working with. If you like to specify the directory path by using relative path names, you need to set the current working directory using the SetCurrentDirectory() method; if not, the default current directory is always the location of your program. Also, notice that some methods (such as GetParent()) still return DirectoryInfo objects.

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