Programmers Heaven: C# School

14. The File System & Streams

Lesson Plan

Today we will learn how we can manipulate the Windows file system and different types of streams using C# and

.Net. We will start out by looking at how we can manipulate physical drives, folders and files, and perform different operations on them. In the second half of the lesson, we will explore the different types of streams used in

.Net and see how we can read data from and write data to files. Finally we will learn about the concept of serialization of objects and how we can implement serialization in C#. The lesson also contains a supplementary topic on Asynchronous I/O.

Working with the File System

This section is further divided into three parts. In the first part, we will see how we can get the software system’s environment information, e.g. the path to the Windows System folder & the Program Files folder, current user name, operating system version, etc. In the second part, we will learn how to perform common file operations such as copying, moving, deleting, renaming and more. In the last part of this section, we will explore directory (or Folder) manipulation techniques.

Obtaining the Application’s Environment Information – The System.Environment class

The System.Environment class is the base class used to obtain information about the environment of our application. The description of some of its properties and methods is presented in the following table:

Demonstration Application – Environment Information

Let’s make a demonstration application that uses the above mentioned properties and methods to display environment information. It is a windows application project that contains a list box named ‘lbx’ which is used to

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display the information, a button named ‘btnGo’ which will be used to start fetching the information and a button named ‘btnExit’ which terminates the application. The main logic is present inside the Go button's event handler:

private void btnGo_Click(object sender, System.EventArgs e)

{

OperatingSystem os = Environment.OSVersion;

PlatformID OSid = os.Platform;

string[] drives = Environment.GetLogicalDrives(); string drivesString = "";

foreach(string drive in drives)

{

drivesString += drive + ", ";

}

drivesString = drivesString.TrimEnd(' ', ',');

}

Here we have simply retrieved the environment information from public properties and methods and added them to the list box. A few important things to note here are:

•Environment.GetLogicalDrives() returns an array of strings, with each string representing the drive name.

•Environment.Version returns an object of type System.Version which contains the detailed information about the current version of the common language runtime (CLR).

•The event handler for exit button simply calls the Exit() method of the Environment class to terminate the current process.

private void btnExit_Click(object sender, System.EventArgs e)

{

Environment.Exit(0);

}

Here we have passed zero to the Exit() method. This value will be returned to the Operating System and can be used to check whether the program terminates successfully or not. When I executed this program to my system, I got the following result:

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Obtaining the paths of various Windows Standard folders – Environment.GetFolderPath()

The method Environment.GetFolderPath() can be used to get the complete paths of various windows standard folders on the current machine. The only argument passed to the method is a value from the System.Environment.SpecialFolder enumeration. Some of the more common members of this enumeration are:

Let’s use these in a simple program to understand their functionality. We can modify the previous program to include these results by changing the btnGo_Click method to:

private void btnGo_Click(object sender, System.EventArgs e)

{

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OperatingSystem os = Environment.OSVersion;

PlatformID OSid = os.Platform;

string[] drives = Environment.GetLogicalDrives(); string drivesString = "";

foreach(string drive in drives)

{

drivesString += drive + ", ";

}

drivesString = drivesString.TrimEnd(' ', ',');

Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles));

lbx.Items.Add("Common Program Files:\t" +

Environment.GetFolderPath(Environment.SpecialFolder.CommonProgramFiles));

Environment.GetFolderPath(Environment.SpecialFolder.History));

lbx.Items.Add("Personal (My Documents:\t" +

Environment.GetFolderPath(Environment.SpecialFolder.Personal));

lbx.Items.Add("Start Menu's Program:\t" +

Environment.GetFolderPath(Environment.SpecialFolder.Programs));

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