VB.NET File Handling

A file is a collection of data stored in computer memory with a specific name and a defined folder path. The term File Handling in VB.NET is used to perform various operations like create a file, read a file, write to the file, closing the file, and more. Furthermore, when a file is opened for reading and writing, a stream is created.

A stream is a sequence of bytes that passes data to a file to read or write. In VB.NET file handling, there are two types of stream such as Input Stream or Read Stream and Output Stream or Write Stream.

VB.NET I/O Classes

In VB.NET, we use the System.IO namespace, that has different classes to perform various input and output operations with files, such as the FileStream class used to perform any operation like opening a file, closing a file, deleting a files, reading from or writing to a file, etc.

The following table shows the I/O classes that are commonly used in VB.NET programming.

I/O Class	Description
File	It is used to perform some changes in files.
FileInfo	It is used to perform any operation on files.
FileStream	It is used to apply read or write operations on any location of a file.
BinaryReader	As the name represents, a Binary reader is used to read primitive data in a binary stream.
BinaryWriter	It is used to write the data in binary format.
Directory	It is used to perform some changes or manipulating a directory structure.
DriveInfo	It helps to provide the necessary information for the drive.
BuffredStream	It is a temporary storage area for the collection of steam bytes.
MemoryStream	It is used to access stored streaming data in memory.
StreamReader	A StreamReader property is used to read characters from the stream byte.
Path	It is used to perform operations on the path of a file.
StreamWriter	A StreamWriter is used to write characters to a stream.
DirectoryInfo	It is used to perform an operation on the directory.
StringReader	It is used to read string from a string buffer.

FileStream Class

The FileStream class is provided by the System.IO namespace to read, write, close or create files in the file handling.

Syntax:

Dim Obj_name As FileStream = New FileSteam("file_name", FileMode, FileAccess, FileShare)

For example, we need to create a FileStream Object FS to read a file with named myfile.txt.

Dim FS As FileStream = New FileStream("myFile.txt", FileMode.Open, FileAccess.ReadWrite)

The following table is the description of FilesStream Class.

Parameter	Description
FileMode	The FileMode represents the various method for opening or creating a file. Following are the member of FileMode- Append: It is used to open an existing file and put the cursor at the end of the file. And if the file is not existing, it creates a file. Create: As the name defines, a create is uses to create a new file. CreateNew: It specifies the OS to create a new file. Open: It is used to open an existing file. OpenOrCreate: It is used to open an existing file, and if the file is not existing, it creates a new file. Truncate: It is used to open an existing file for shrinking its original size to zero bytes.
FileAccess	It is used to perform any operation such as Read, ReadWrite, Delete and Write, etc.
FileShare	A FileShare has the following members Read: It permits to open a file for reading Write: It permits you to open a file for writing. None: It is used to reject the sharing of the current file.
Obj_name	It represents the object name of the file.

Let's create a program to understand the concept of FileStream in VB.NET program.

File_Prog.vb

Imports System.IO
Module File_Prog
    Sub Main()
' Create an object FS for the FileStream class along with the name of the text file to perform operation like create, read or write.
        Dim FS As FileStream = New FileStream("myFile.txt", FileMode.OpenOrCreate, FileAccess.ReadWrite)
        Dim c As Integer
        ' use for loop to read character
        For c = 0 To 21
            FS.WriteByte(CByte(c))  'write byte to the file
        Next c
        FS.Position = 0
        Console.WriteLine("Bytes are:")
        For c = 0 To 21
        Console.WriteLine("{0} ", FS.ReadByte()) ' ReadByte() to read byte form the file.
        Next c
        FS.Close()  'Close the file
        Console.WriteLine(" Press any key to exit...")
        Console.ReadKey()
    End Sub
End Module

Output:

VB.NET has some advanced concepts of file operation.

1. StreamReader and StreamWriter

The StreamReader class is used to read a text from a text file, and the StreamWrite file is used to write a text to a specified text file. These Stream classes are inherited from the Abstract base class stream, which represents a reader to read a series of characters, and a writer can write a series of characters.

Example of StreamReader Class

Let's create the following example to understand the concept of StreamReader to read a text file named Myfile.txt, as shown below.

Myfile.txt

What is an Exception?
An exception is an unwanted error that occurs during the execution of a program and can be a system exception or application exception.

StReader.vb

Imports System.IO
Module StReader
    Sub Main()
        ' Create St as an object of StreamReader Class
        Dim St As StreamReader = New StreamReader("C:/Users/AMIT YADAV/Desktop/Myfile.txt")
        Dim ln As String
        ' It reads and prints the content from Myfile.txt
        ln = St.ReadLine()
        While (ln <> Nothing)
            Console.WriteLine(ln)
            ln = St.ReadLine()
        End While
        St.Close()
        Console.ReadKey()
    End Sub
End Module

Output:

Example of StreamWriter Class

Let's create the following example to understand the concept of StreamWriter to write a text into a file Mytext.txt, as shown below.

StWriter.vb

Imports System.IO
Module StWriter
    Sub Main()
        Dim ln As String
        ' Create a path for Mytext.txt file to insert the below data. 
        Dim St As StreamWriter = New StreamWriter("C:/Users/AMIT YADAV/Desktop/Mytext.txt")
        St.WriteLine(" Welcome To JavaTpoint")
        St.WriteLine(" VB.NET is the Programming language")
        St.WriteLine(" Learn VB.NET File Handling")
        St.Close()

        ' Read and print the data from the specified file.
        Dim sw As StreamReader = New StreamReader("C:/Users/AMIT YADAV/Desktop/Mytext.txt")
        ln = sw.ReadLine()
        While (ln <> Nothing)
            Console.WriteLine(ln)
            ln = sw.ReadLine()
        End While
        sw.Close()
        Console.WriteLine("Press any key to exit...")
        Console.ReadKey()
    End Sub
End Module

Output:

Further, we can also check if the file "Mytext.txt" is created on the defined route "C:/Users/AMIT YADAV/Desktop/Mytext.txt" or not. And when we follow the defined path, it shows the following content in Mytext file.

Note: Only one stream can be opened at a time. Therefore, in the above example, we first wrote data to the file and then closed the stream. After that, we open the Read stream to read the text and then closed the stream

2. BinaryReader and BinaryWriter Classes

The BinaryReader and BinaryWriter classes are used with binary streams. Binary data is read and write using its internal binary format, and these binary data are not human readable. The BinaryReader class can be used to read binary data from a file, and the BinaryWriter file is used to write text to a specified binary file.

Example of BinaryWriter Class

Let's create the following example to understand the concept of StreamWriter to write a text into a file Mytext.txt, as shown below.

BinWriter.vb

Imports System.IO
Module BinWriter
    Sub Main()
        Dim FS As FileStream = New FileStream("C:\Users\AMIT YADAV\Desktop\Myfolder\binary.txt", FileMode.OpenOrCreate, FileAccess.Write)
        Dim binWriter As New BinaryWriter(FS)
        Dim name As String = "Welcome to JavaTpoint"
        Dim db As Double = 1010
        Dim age As Integer = 10111
        binWriter.Write(name)
        binWriter.Write(db)
        binWriter.Write(age)
        binWriter.Close()
        FS.Close()
        Console.WriteLine(" Press any key to exit...")
        Console.ReadKey()
    End Sub
End Module

Output:

Example of BinaryReader Class

Let's create the following example to understand the concept of BinaryReader to read the text into a file Mytext.txt.

BinReader.vb

Imports System.IO
Module BinReader
    Sub Main()
        Dim FS As FileStream = New FileStream("C:\Users\AMIT YADAV\Desktop\Myfolder\binary.txt", FileMode.Open, FileAccess.Read)
        Dim binReader As New BinaryReader(FS)
        Dim a As Integer = binReader.ReadInt32()
        Dim c As Char = binReader.ReadChar()
        Dim f As Single = binReader.ReadSingle()
        Console.WriteLine("Integer is {0}", a)
        Console.WriteLine("Char data is {0}", c)
        Console.WriteLine(" Float data is {0}", f)
        binReader.Close()
        FS.Close()
        Console.WriteLine(" Press any key to exit...")
        Console.ReadKey()
    End Sub
End Module

Output:

3. FileInfo Class

The FileInfo class is used to get file properties such as file creation, copying, moving, name, and size. It also helps to create a FileStream object, and the FileInfo class is derived from the FileSystemInfo class.

Let's create an example to understand the concept of the FileInfo class in VB.NET.

GetFilename.vb

Imports System.IO
Module GetFilename
    Sub Main()
        Dim mk As DirectoryInfo = New DirectoryInfo("C:\Users\AMIT YADAV\Desktop\Myfolder")
        Dim fl As FileInfo() = mk.GetFiles()
        Dim f As FileInfo
        For Each f In fl
            Console.WriteLine(" Name of File: {0} Size: {1} Creation time: {2} Extension of file is :{3}", f.Name, f.Length, f.CreationTime, f.Extension)
        Next f
        Console.WriteLine("Press any key to exit...")
        Console.ReadKey()
    End Sub
End Module

Output: