VB.Net

VB.Net File Handling

VB.Net File Handling

VB.Net File Handling

A file is a collection of data on a disc that has a unique name and a directory path. When a file is opened for reading or writing, it is transformed into a stream.

The stream is essentially a sequence of bytes traversing the communication route. The input and output streams are the two main streams. The input stream is used to read data from the file (read operation), and the output stream is used to write data into the file (write action) (write operation).

VB.Net I/O Classes

The System.IO namespace contains classes for performing different file operations like creating and deleting files, reading from or writing to a file, closing a file, and so on.

The table below lists some of the most often used non-abstract classes in the System.IO namespace.

I/O Class

Description

BinaryReader

Reads primitive data from a binary stream.

BinaryWriter

Writes primitive data in binary format.

BufferedStream

A temporary storage for a stream of bytes.

Directory

Helps in manipulating a directory structure.

DirectoryInfo

Used to perform operations on directories.

DriveInfo

Provides information for the drives.

File

Used for manipulating files.

FileInfo

For performing operations on files.

FileStream

Used to read and write to any location in a file.

MemoryStream

Used for random access of streamed data stored in memory.

Path

Performs operations on path information.

StreamReader

Used for reading characters from a byte stream.

StreamWriter

It is used for writing characters to a stream.

StringReader

It is used for reading from a string buffer.

StringWriter

It is used for writing into a string buffer.

The FileStream Class

The System.IO namespace's FileStream class aids in reading from, writing to, and closing files. This class is a subclass of the abstract class Stream.

To create a new file or open an existing one, you must first create a FileStream object. The following is the syntax for creating a FileStream object −

Dim <object_name> As FileStream = New FileStream(<file_name>, <FileMode Enumerator>, <FileAccess Enumerator>, <FileShare Enumerator>)

For example, for creating a FileStream object F for reading a file named sample.txt −

Dim f1 As FileStream = New FileStream("sample.txt", FileMode.OpenOrCreate, FileAccess.ReadWrite)

Parameter

Description

FileMode

The FileMode enumerator defines several file-opening mechanisms. The FileMode enumerator's members are as follows:

  • Append- It opens an existing file and places the cursor at the end of the file, or it creates the file if it does not exist.
  • Create- It generates a new file.
  • CreateNew- This command instructs the operating system to create a new file.
  • Open- It opens a previously saved file.
  • OpenOrCreate- It tells the operating system that if a file exists, it should open it; otherwise, it should create a new file.
  • Truncate This command opens an existing file and reduces its size to zero bytes.

FileAccess

FileAccess enumerators have members: ReadWriteReadWrite.

FileShare

Listed below are the members of FileShare enumerators −

  • Inheritable – a filehandle can pass an inheritance to the child processes using this.
  • None − It is for declining sharing of the current file
  • Read – To open the file for reading
  • ReadWrite – To open the file for reading and writing
  • Write – To open the file for writing

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