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Note: You need to add a text file called "file.txt" and include it in the build directory ("Copy if newer").
Using: Look at how the Using-statement is formed to create the StreamReader. This is the most common usage pattern for StreamReader.
Also: We include the System.IO namespace at the top, with the line "Imports System.IO". This is important to compile the program.
VB.NET program that uses StreamReader
Imports System.IO
Module Module1
Sub Main()
' Store the line in this String.
Dim line As String
' Create new StreamReader instance with Using block.
Using reader As StreamReader = New StreamReader("file.txt")
' Read one line from file
line = reader.ReadLine
End Using
' Write the line we read from "file.txt"
Console.WriteLine(line)
End Sub
End Module
Output
(Contents of file.)
Also: There is a local line variable declared, which will store each line as it is read.
ListInfo: Before the loop begins, we read the first line of the file. Then we enter a Do While loop, which continues until the last line read is Nothing.
While, Do WhileNothingEnd: At the end of the program, I inserted a debugger breakpoint to show the contents of the List.
And: I found that there were two string elements, containing Line 1 and Line 2 of the text file we read.
VB.NET program that uses StreamReader and List
Imports System.IO
Module Module1
Sub Main()
' We need to read into this List.
Dim list As New List(Of String)
' Open file.txt with the Using statement.
Using r As StreamReader = New StreamReader("file.txt")
' Store contents in this String.
Dim line As String
' Read first line.
line = r.ReadLine
' Loop over each line in file, While list is Not Nothing.
Do While (Not line Is Nothing)
' Add this line to list.
list.Add(line)
' Display to console.
Console.WriteLine(line)
' Read in the next line.
line = r.ReadLine
Loop
End Using
End Sub
End Module
Finally: There are other methods on the File class that can simplify some of this code, but StreamReader proves to be an important tool.