Input And Output in Visual Basic

Input & Output

This chapter is dedicated to Input & Output in Visual Basic. The Input & Output in Visual Basic is based on streams.
Streams are objects to work with Input/Output. A stream is an abstraction of a sequence of bytes, such as a file, an input/output device, an inter-process communication pipe, or a TCP/IP socket. In Visual Basic, we have a Stream class, that is an abstract class for all streams. There are additional classes that derive from the Stream class and make the programming a lot easier.

MemoryStream

A MemoryStream is a stream which works with data in a computer memory.

Option Strict On


Imports System.IO

Module Example

   Sub Main()

      Dim ms As Stream = New MemoryStream(6)

      ms.WriteByte(9)
      ms.WriteByte(11)
      ms.WriteByte(6)
      ms.WriteByte(8)
      ms.WriteByte(3)
      ms.WriteByte(7)

      ms.Position = 0

      Dim rs As Integer
      rs = ms.ReadByte()

      Do While rs <> -1
        Console.WriteLine(rs)
        rs = ms.ReadByte()
      Loop

      ms.Close()

   End Sub 

End Module

We write six numbers to a memory with a MemoryStream. Then we read those numbers and print them to the console.

Dim ms As Stream = New MemoryStream(6)

The line creates and initializes a MemoryStream object with a capacity of six bytes.

ms.Position = 0

We set the position of the cursor in the stream to the beginning using the Position property.

ms.WriteByte(9)
ms.WriteByte(11)
ms.WriteByte(6)
...

The WriteByte() method writes a byte to the current stream at the current position.

Do While rs <> -1
  Console.WriteLine(rs)
  rs = ms.ReadByte()
Loop

Here we read all bytes from the stream and print them to the console.

ms.Close()

Finally, we close the stream.

$ ./memory.exe 
9
11
6
8
3
7

Output of the example.