VB.NET File Handling Overview

File handling is an important aspect of any programming language, and VB.NET accomplishes this with the help of various classes and methods provided by the .NET framework. In this page, we will give an overview of file handling in VB.NET.

Syntax

The syntax of file handling in VB.NET involves the use of FileStream, StreamReader, StreamWriter, BinaryReader, and BinaryWriter classes.

To read from a file, you can use the following syntax:

Dim fs As New FileStream("path to file", FileMode.Open, FileAccess.Read)
Dim sr As New StreamReader(fs)
Dim str As String = sr.ReadToEnd()
sr.Close()
fs.Close()

To write to a file, you can use the following syntax:

Dim fs As New FileStream("path to file", FileMode.Create, FileAccess.Write)
Dim sw As New StreamWriter(fs)
sw.WriteLine("Hello, World!")
sw.Close()
fs.Close()

Example

Here's an example of file handling in VB.NET. This code reads the contents of a file and writes some text to it.

Imports System.IO

Module FileHandlingExample

    Sub Main()
        
        ' Read from a file
        Dim fs As New FileStream("usernames.txt", FileMode.Open, FileAccess.Read)
        Dim sr As New StreamReader(fs)
        Dim contents As String = sr.ReadToEnd()
        Console.WriteLine("File contents:")
        Console.WriteLine(contents)
        sr.Close()
        fs.Close()
        
        ' Append to the same file
        Dim fs2 As New FileStream("usernames.txt", FileMode.Append, FileAccess.Write)
        Dim sw As New StreamWriter(fs2)
        sw.WriteLine("New user added.")
        sw.Close()
        fs2.Close()
        
        ' Read from the file again
        Dim fs3 As New FileStream("usernames.txt", FileMode.Open, FileAccess.Read)
        Dim sr2 As New StreamReader(fs3)
        Dim contents2 As String = sr2.ReadToEnd()
        Console.WriteLine("File contents:")
        Console.WriteLine(contents2)
        sr2.Close()
        fs3.Close()
        
        Console.ReadKey()

    End Sub

End Module

Output

The output of the above program would be as follows:

File contents:
John
Sarah
Michael

File contents:
John
Sarah
Michael
New user added.

Explanation

File handling in VB.NET is accomplished through the use of streams and readers/writers. The FileStream class can be used to create a stream to a file with different modes, such as FileMode.Open or FileMode.Create. In order to read or write data to the file, readers and writers can be used, such as StreamReader or StreamWriter.

In the above example, we first read from a file called "usernames.txt" using a FileStream and StreamReader. Then, we append some text to the same file using a StreamWriter and a new FileStream with FileMode.Append. Finally, we read from the file again to see the updated contents.

Use

File handling in VB.NET is used to read or write to files in various formats, such as text files or binary files. It is commonly used in applications that require data to be stored or retrieved from files, such as reading configuration settings or writing log files.

Important Points

• VB.NET has various classes and methods for file handling, including FileStream, StreamReader, StreamWriter, BinaryReader, and BinaryWriter.
• Streams and readers/writers are used to read and write data to files.
• File handling is commonly used in applications that require data to be stored or retrieved from files.

Summary

In this page, we gave an overview of file handling in VB.NET. We covered the syntax, example, output, explanation, use, important points, and summary of file handling in the language. By understanding the different classes and methods for file handling in VB.NET, developers can read and write data to files in their applications.