Read specific columns and rows from .text - vb.net

Question

Well, I need to read columns and rows from a .txt
and get only the data I need.
Example: The file "sample.txt" has the following content
C = Columns
R = Rows
C1 C2 C3
R1 0 0 0 3694440008091082330089 ALBINA HANSEN OF OLMEDO 00000075000000022091401520117873
I need the following data for each row:
0003694440008091082330089 ALBINA HANSEN DE OLMEDO 00000075000000022091401520117873
(The series of numbers and letters above the value of the first line)
First Value: Starts at C19 to C25 (2330089)
Second Value: Starts at C28 to C50 (ALBINA HANSEN DE OLMEDO)
Third Value: Starts at C64 to C68 (75000)
Fourth Value: Starts at C73 to C78 (220914)
Fifth Value: It is only the C80 column (1)
And I need to display the data in a message box:
I have the following code:
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim fileReader As String
fileReader = My.Computer.FileSystem.ReadAllText("C:\Users\cogentvaio\Desktop\Banco Itau\TXT-FOMENTO ANGELIUS.txt")
MsgBox(fileReader)
End Sub
End Class
This allows me to read the entire contents of .txt
Hopefully you can help me with this, I'm learning to program in vb.net.
I'll show you my code, I can not see the boundaries made with ​​substrinng, I used the code you suggested,
Imports System
Imports System.IO
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim fileReader = My.Computer.FileSystem.ReadAllText("C:\Users\cogentvaio\Desktop\Banco Itau\ejemplo\-TXT-ITAU ANGELIUS.txt")
Dim line As String
For Each line In fileReader
If line.Length > 80 Then
Dim c1 = line.Substring(18, 7)
Dim c2 = line.Substring(28, 50)
Dim c3 = line.Substring(64, 68)
Dim c4 = line.Substring(73, 78)
Dim c5 = line.Substring(80)
End If
Next
MessageBox.Show(fileReader)
End Sub
End Class
And what I got was this
IMAGE_PHOTO
I don't know where is my mistake

Answer 1

string.Substring is your friend here. This method extracts substring from a string starting from a char index and getting back the requested number of chars (length). Also remember that an array (a string is an array of chars) starts always at index zero, so your values Cx values should be decremented by one.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
' Instead of ReadAllText, use ReadAllLines to have your input splitted in an array of strings
Dim fileReader = System.IO.File.ReadAllLines(......)
for each line in fileReader
' To avoid nasty exceptions be sure that the line is at least 81 chars long
if line.Length > 80 Then
Dim c1 = line.Substring(18, 7)
Dim c2 = line.Substring(27, 23)
Dim c3 = line.Substring(63, 5)
Dim c4 = line.Substring(72, 6)
Dim c5 = line.Substring(79, 1)
.... process these values....
.... for example ....
Dim newLine = string.Join(" ", c1,c2,c3,c4,c5)
MessageBox.Show(newLine)
End if
Next
End Sub
This changes takes a line, extract the part and creates a new string with only the parts required joined together with a space. Then prints out this new text. Of course, you want a join of all the rows with these subparts you need to add the newLine variable to a List( Of String) an then do a final join of the single rows
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
' Instead of ReadAllText, use ReadAllLines to have your input splitted in an array of strings
Dim fileReader = System.IO.File.ReadAllLines(......)
Dim subText = New StringBuilder()
for each line in fileReader
if line.Length > 80 Then
....
Dim newLine = string.Join(" ", c1,c2,c3,c4,c5)
subText.Add(newLine)
End if
Next
MessageBox.Show(string.Join(Environment.NewLine, subText))
However your indexes doesn't seem to correctly point to the data required.
This substring extraction seems to find correctly your data
Dim c1 = line.Substring(18, 7)
Dim c2 = line.Substring(26, 23)
Dim c3 = line.Substring(56, 5)
Dim c4 = line.Substring(65, 6)
Dim c5 = line.Substring(72, 1)