Search a string from text file & Return the Line Number using VBA - excel

Question

I have one text file that contains around 100K lines. Now I would like to search a string from the text file. If that string is present then I want to get the line number at which it's present. At the end I need all the occurrence of that string with line numbers from the text file.
* Ordinary Method Tried *
We can read the whole text file line by line. Keep a counter variable that increases after every read. If I found my string then I will return the Counter Variable. The limitation of this method is, I have to traverse through all the 100K lines one by one to search the string. This will decrease the performance.
* Quick Method (HELP REQUIRED)*
Is there any way that will directly take me to the line where my searchstring is present and if found I can return the line number where it's present.
* Example *
Consider below data is present in text file. (say only 5 lines are present)
Now I would like to search a string say "Pune". Now after search, it should return me Line number where string "pune" is present. Here in this case it's present in line 2. I should get "2" as an output. I would like to search all the occurrence of "pune" with their line numbers

Answer 1

I used a spin off of Me How's code example to go through a list of ~10,000 files searching for a string. Plus, since my html files have the potential to contain the string on several lines, and I wanted a staggered output, I changed it up a bit and added the cell insertion piece. I'm just learning, but this did exactly what I needed and I hope it can help others.
Public Sub ReadTxtFile()
Dim start As Date
start = Now
Dim oFSO As Object
Set oFSO = CreateObject("Scripting.FileSystemObject")
Dim oFS As Object
Dim filePath As String
Dim a, b, c, d, e As Integer
a = 2
b = 2
c = 3
d = 2
e = 1
Dim arr() As String
Do While Cells(d, e) <> vbNullString
filePath = Cells(d, e)
ReDim arr(5000) As String
Dim i As Long
i = 0
If oFSO.FileExists(filePath) Then
On Error GoTo Err
Set oFS = oFSO.OpenTextFile(filePath)
Do While Not oFS.AtEndOfStream
arr(i) = oFS.ReadLine
i = i + 1
Loop
oFS.Close
Else
MsgBox "The file path is invalid.", vbCritical, vbNullString
Exit Sub
End If
For i = LBound(arr) To UBound(arr)
If InStr(1, arr(i), "Clipboard", vbTextCompare) Then
Debug.Print i + 1, arr(i)
Cells(a + 1, b - 1).Select
Selection.Insert Shift:=xlDown
Cells(a, b).Value = i + 1
Cells(a, c).Value = arr(i)
a = a + 1
d = d + 1
End If
Next
a = a + 1
d = d + 1
Loop
Debug.Print DateDiff("s", start, Now)
Exit Sub
Err:
MsgBox "Error while reading the file.", vbCritical, vbNullString
oFS.Close
Exit Sub
End Sub

Answer 2

the following fragment could be repalaced like:
Dim arr() As String
Dim i As Long
i = 0
If oFSO.FileExists(filePath) Then
On Error GoTo Err
Set oFS = oFSO.OpenTextFile(filePath)
Do While Not oFS.AtEndOfStream
ReDim Preserve arr(0 To i)
arr(i) = oFS.ReadLine 'to save line's content to array
'If Len(oFSfile.ReadLine) = 0 Then Exit Do 'to get number of lines only
i = i + 1
Loop
oFS.Close
Else
MsgBox "The file path is invalid.", vbCritical, vbNullString
Exit Sub
End If

Answer 3

Here's another method that should work fairly quickly. It uses the shell to execute the FINDSTR command. If you find the cmd box flickers, do an internet search for how to disable it. There are two options provided: one will return the line number followed by a colon and the text of the line containing the keyword. The other will just return the line number.
Not sure what you want to do with the results, so I just have them in a message box.
Option Explicit
'Set reference to Windows Script Host Object Model
Sub FindStrings()
Const FindStr As String = "Pune"
Const FN As String = "C:\users\ron\desktop\LineNumTest.txt"
Dim WSH As WshShell
Dim StdOut As Object
Dim S As String
Set WSH = New WshShell
Set StdOut = WSH.Exec("cmd /c findstr /N " & FindStr & Space(1) & FN).StdOut
Do Until StdOut.AtEndOfStream
S = S & vbCrLf & StdOut.ReadLine
'If you want ONLY the line number, then
'S = S & vbCrLf & Split(StdOut.ReadLine, ":")(0)
Loop
S = Mid(S, 2)
MsgBox (S)
End Sub