How to execute basic file I/O in Visual C #

Demonstrate file I/O operations

The example in this article describes basic file I/O operations. The step-by-step example section describes how to create an example program that demonstrates the following six file I/O operations:

•	Read text files
•	Write a text file
•	View File Information
•	List disk drives
•	List folders
•	List objects

Note:: If you want to use the following sample code directly, note the following:

•	Must includeSystem. IoThe namespace is as follows: using System.IO;
•	Declare as followsWindirVariable: string winDir=System.Environment.GetEnvironmentVariable("windir");
•	Declare as followsAddlistitemFunction: private void addListItem(string value){this.listbox1.Items.Add(value);} Note:: You can directly use the following statements without declaring and using them.AddlistitemFunction: this.listbox1.Items.Add(value);"

Read text files

Use the following sample codeStreamreaderClass to read the system. ini file. The content of this file is added toListBoxControl. TheTry... catchBlocks are used to send alerts to programs when files are empty. There are multiple ways to determine whether the end of the file is reached; this example usesPeekMethod: Check the row before reading the row.

    StreamReader reader=new  StreamReader(winDir + "//system.ini");        try           {                do            {                addListItem(reader.ReadLine());            }               while(reader.Peek() != -1);        }                       catch         {             addListItem("File is empty");}        finally        {            reader.Close();        }

Write a text file

This sample code usesStreamwriterClass to create a file and write information. If an existing file already exists, you can open it in the same way.

    StreamWriter writer = new StreamWriter("c://KBTest.txt");    writer.WriteLine("File created using StreamWriter class.");    writer.Close();    this.listbox1.Items.Clear();    addListItem("File Written to C://KBTest.txt");

View File Information

This sample code usesFileinfoObject. Notepad.exe is used in this example. Attribute inListBoxControl.

    FileInfo FileProps  =new FileInfo(winDir + "//notepad.exe");    addListItem("File Name = " + FileProps.FullName);    addListItem("Creation Time = " + FileProps.CreationTime);    addListItem("Last Access Time = " + FileProps.LastAccessTime);    addListItem("Last Write TIme = " + FileProps.LastWriteTime);    addListItem("Size = " + FileProps.Length);    FileProps = null;

List disk drives

Use this sample codeDirectoryAndDriveClass to list the logical drives on the system. The results in this example are displayed inListBoxControl.

    string[] drives = Directory.GetLogicalDrives();    foreach(string drive in drives)    {        addListItem(drive);    }

List subfolders

Use this sample codeDirectoryClassGetdirectoriesMethod to obtain the folder list.

    string[] dirs = Directory.GetDirectories(winDir);    foreach(string dir in dirs)        {            addListItem(dir);        }

List objects

This example usesDirectoryClassGetfilesMethod to obtain the folder list.

    string[] files= Directory.GetFiles(winDir);    foreach (string i in files)    {        addListItem(i);    }

Multiple errors may occur when users access files. The file may not exist or may be in use, or the user has no permission to access the files in the folder to be accessed. It is important to consider these possibilities when writing code and handling possible exceptions.