Searching multiple .txt files for all occurrences of a string? - regex

Question

I am trying to create a tool that will search 300+ .txt files for a string that that may be used several times in each of the 300+ .txt files
I want to be able to go through each file and get the string between each of the occurrences.
It sounds a bit twisted I know, I have been scratching my head for hours, while testing code.
What I have tried
I read through each file and check for if it contains my search text at least once, if it does, then I add the full path of the (files that do contain it) to a list
Dim FileNamesList As New List(Of String)
Dim occurList As New List(Of String)
Dim textSearch As String = TextBox1.Text.ToLower
'check each file to see if it even contains textbox1.text
'if it does, then add matching files to list
For Each f As FileInfo In dir.GetFiles("*.txt")
Dim tmpRead = File.ReadAllText(f.FullName).ToLower
Dim tIndex As Integer = tmpRead.IndexOf(textSearch)
If tIndex > -1 Then
FileNamesList.Add(f.FullName)
End If
Next
Then I thought, oh, now all I need to do is go through each string in that 'approved' files list and add the entire contents of each to a new list.
Then I go through each in 'that' list and get string between two delimiters.
And... I just get lost from there...
Here is the get string between delimiters I have tried using.
Private Function GetStringBetweenTags(ByVal startIdentifer As String, ByVal endIndentifier As String, ByVal textsource As String) As String
Dim idLength As Int16 = startIdentifer.Length
Dim s As String = textsource
Try
s = s.Substring(s.IndexOf(startIdentifer) + idLength)
s = s.Substring(0, s.IndexOf(endIndentifier))
'MsgBox(s)
Catch
End Try
Return s
End Function
In simple terms...
I have 300 .txt files
Some may contain a string that I am after
I want the substring of each string
Normally I am fine, and never need to ask questions, but there is too many forceptions going on.
Logical Example
== Table.txt ==
print("I am tony")
print("pineapple")
print("brown cows")
log("cable ties")
log("bad ocd")
log("bingo")
== Cherry.txt ==
print("grapes")
print("pie")
print("apples")
log("laugh")
log("tuna")
log("gonuts")
== Tower.txt ==
print("tall")
print("clouds")
print("nomountain")
log("goggles?")
log("kuwait")
log("india")
I want to end with list of the text between only the print function from all 3 files
Haven't found any other thread about this, probably because it stupid.
So I should end with
== ResultList ==
I am tony
pineapple
brown cows
grapes
pie
apples
tall
clouds
nomountain

Answer 1

RegEx is probably your best choice for something like this. For instance:
Dim results As New List(Of String)()
Dim r As New RegEx("print\(""(.*)""\)")
For path As String In filePaths
Dim contents As String = File.ReadAllText(path)
For Each m As Match in r.Matches(contents)
If m.Sucess Then
results.Add(m.Groups(1).Value)
End If
Next
Next
As you can see, the code loops through a list of file paths. For each one, it loads the entire contents of the file into a string. It then searches the file contents string for all matches to the following regular expression pattern: print\("(.*)"\). It then loops through all of those pattern matches and grabs the value of the first capture group from each one. Those are added to the results list, which contains your desired strings. Here's the meaning of the parts of the RegEx:
print - Looks for any string starting with the word "print"
\( - The next character after the word "print" must be an open parentheses (the backslash is an escape character)
" - The next character after the open parentheses must be a double quote character (it is repeated twice so as to escape it so that VB doesn't think it's the end of the string).
(.*) - The parentheses define this as a capturing group (so that we can pull out just this value from the matches). The .* means any characters of any length.
"\) - Matching strings must end with a double quote followed by a closing parentheses.

Answer 2

Use Regex:
Imports System.Text.RegularExpressions
Module Module1
Sub Main()
Dim input1 As String = _
"print(""I am tony"") " + _
"print(""pineapple"") " + _
"print(""brown cows"") " + _
"log(""cable ties"") " + _
"log(""bad ocd"") " + _
"log(""bingo"")"
Dim input2 As String = _
"print(""grapes"") " + _
"print(""pie"") " + _
"print(""apples"") " + _
"log(""laugh"") " + _
"log(""tuna"") " + _
"log(""gonuts"")"
Dim input3 As String = _
"print(""tall"") " + _
"print(""clouds"") " + _
"print(""nomountain"") " + _
"log(""goggles?"") " + _
"log(""kuwait"") " + _
"log(""india"")"
Dim pattern As String = "print\(""([^""]*)""\)"
Dim expr As Regex = New Regex(pattern, RegexOptions.Singleline)
Dim matches As MatchCollection = Nothing
Dim data As List(Of String) = New List(Of String)()
matches = expr.Matches(input1)
For Each mat As Match In matches
data.Add(mat.Groups(1).Value)
Next mat
matches = expr.Matches(input2)
For Each mat As Match In matches
data.Add(mat.Groups(1).Value)
Next mat
matches = expr.Matches(input3)
For Each mat As Match In matches
data.Add(mat.Groups(1).Value)
Next mat
End Sub
End Module