Display String From Text File in a Label Box in Visual Basic - vb.net

Question

So I am trying to make a code where the user inputs an ID number and receives the line of text that the ID corresponds to. I am having trouble with the code as I am unable to display the result (or correct result) in a label box.
For example:
If I type in ID 1, it displays the data that corresponds to ID 2, ID 2 corresponds to ID 3 and ID 3 ends the loop (there are only 3 records in the data currently).
I have included my code below
Private Sub btnSearch_Click(sender As Object, e As EventArgs) Handles btnSearch.Click
Filename = "NamesAndAges.txt"
FileOpen(1, Filename, OpenMode.Input,,,)
Dim ID As Integer
ID = txtSearch.Text
Dim Found As Boolean
Found = False
Do While Not EOF(1) And Found = False
If LineInput(1).Contains(ID) Then
lblDisplaySearch.Text = LineInput(1)
Found = True
Else MsgBox("Not Found")
End If
Loop
FileClose(1)
End Sub
Thanks in advance, would also really appreciate if anyone could explain the code they use as I am still a visual basic beginner.

Answer 1

Every time you call LineInput(1), it reads a line, so you're reading a line and checking if it contains ID then reading another line and setting lblDisplaySearch.Text to that value.
Try something like this:
Dim line As String
Do While Not EOF(1) And Found = False
line = LineInput(1)
If line.Contains(ID) Then
lblDisplaySearch.Text = line
Found = True
Else MsgBox("Not Found")
End If
Loop

Answer 2

I would strongly suggest simplifying this code, by using File.ReadLines:
Private Sub btnSearch_Click(sender As Object, e As EventArgs) Handles btnSearch.Click
Filename = "NamesAndAges.txt"
Dim line = File.ReadLines(Filename).FirstOrDefault(Function(x) x.Contains(txtSearch.Text))
If line Is Nothing Then
MsgBox("Not Found")
Exit Sub
End If
lblDisplaySearch.Text = line
End Sub
The primary advantage is that you don't need to manage the Do While loop. Instead, you are passing the match condition (Function(x) x.Contains(txtSearch.Text)) to the FirstOrDefault method, which internally will find the first line matching the condition and return it, or return Nothing if it's not found.
For Each and IEnumerable
VB.NET allows you to loop over a set of items without knowing or caring about the index within the set. For example:
For Each x As String In File.ReadLines(Filename)
'do something with the line, which is now in x
Next
In order to use For Each with an object, that object has to implement a specific interface — the IEnumerable interface.
Interfaces
Interfaces guarantee that a given object has, or implements, specific members. In this case, if an object implements the IEnumerable interface, that means it has a GetEnumerator method, which the For Each uses under the hood.
IEnumerable(Of T)
The object returned from File.ReadLines implements another more advanced generic interface called IEnumerable(Of T). With this interface, the compiler can figure out automatically that each step of the For Each will be parsing a string, and we don't need to specify it as a string:
For Each x In File.ReadLines(Filename)
'x is known to be a String here
Next
Lambda expressions
The condition "the line which contains the search text" is written as a lambda expression, which (in this case) is made into a method without an explicit name or definition. This is convenient, because we don't have to write this:
Function ContainsCondition(line As String, toFind As String) As Boolean
Return line.Contains(toFind)
End Function`
every time we want to express a condition this way.
Type of x in the condition
Because File.ReadLines returns an IEnumerable(Of T), in this case an IEnumerable(Of String), the compiler can figure out that the condition is working on strings, so we don't have to specify that x is a string within the condition.