Working with System.IO.Directory Class in C#

Output:

Using C# Directory Class, Available drives are:

A:\
C:\
D:\
E:\
Z:\

So lets understand how this works System.IO.Directory class has method called GetLogicalDrives() this method returns all available drives in your system as array of strings. Before that some important thing to remember is all methods of the Directory class are static and can therefore be called without having an instance of a directory. The static methods of the Directory class do a security check on all methods. If you are going to reuse an object several times, consider using the corresponding instance method of DirectoryInfo instead, because the security check will not always be necessary.

Now that we know about Directory class so we will examine the IL code of C# sample (getDr.exe) and also System.IO library.

(IL code of sample code getDr.exe)
IL_0000:call string[] ['mscorlib']'System.IO'.'Directory'::'GetLogicalDrives'()

|

V

(IL code of System.IO library)
IL_000b: call int32 Microsoft.Win32.Win32Native::GetLogicalDrives()

|

V

(IL code of System.IO library)
.method assembly hidebysig static pinvokeimpl("kernel32.dll" lasterr winapi)
int32 GetLogicalDrives() cil managed preservesig

{ }

If you see the above IL code of System.IO library it internally calls the kernel32.dll GetLogicalDrives() which is nothing but File I/O function in Kernel32.dll library which retrieves a bitmask representing the currently available disk drives. When you call Directory Class methods of System.IO library it internally pinvokes the Microsoft Win32 native functions (see the above Platform SDK code).

Similarly we will see a sample code to create and change directory. For this sample code we will be using Directory.CreateDirectory(), Directory.GetCurrentDirectory() ,Directory.Delete(), Directory.Exists() and Directory.SetCurrentDirectory().

chgDr.cs

using System.IO;
class chgDr
{
public static void Main()
{
try
{
Console.WriteLine("-->Your Current Directory");
String curDir=Directory.GetCurrentDirectory();
Console.WriteLine(curDir);
String newDir="TestDir";
Directory.CreateDirectory(newDir);
Console.WriteLine("--> '" + newDir + "' Directory created");
Directory.SetCurrentDirectory(newDir);
Console.WriteLine("--> Changing to '" + newDir + "' Directory ");
Console.WriteLine(Directory.GetCurrentDirectory());
Console.WriteLine("--> Changing to '" + curDir + "' Directory ");
Directory.SetCurrentDirectory(curDir);
Console.WriteLine(Directory.GetCurrentDirectory());
Console.WriteLine("--> Deleting '" + newDir + "' Directory ");
if(Directory.Exists(newDir))
Directory.Delete(newDir);
Console.WriteLine("--> Checking '" + newDir + "' Directory Exists or not");
if(!Directory.Exists(newDir))
Console.WriteLine("'" + newDir + "' Does not exists ");
}
catch(IOException e){ Console.WriteLine(e.ToString()); }
}
}

Output:

D:\samples\vstudio>chgDr
--> Your Current Directory
D:\samples\vstudio
--> 'TestDir' Directory created
--> Changing to 'TestDir' Directory
D:\samples\vstudio\TestDir
--> Changing to 'D:\samples\vstudio' Directory
D:\samples\vstudio
--> Deleting 'TestDir' Directory
--> Checking 'TestDir' Directory Exists or not
'TestDir' Does not exists

Some points to remember:

1. Path names are limited to 248 characters
2. The specified path can also refer to a relative path or a Universal Naming Convention (UNC) path for a server and share name.
3. Ensure that your paths are well-formed when using methods that accept a path string .In C# path names should have \\ instead of singe \
4. If you don't have permission it will generate FileIOPermission exception.

Further reading

1. .Net More information on .Net technologies