How can I look for certain words in a file and then do something? - vb.net

Question

How can I look for certain words in a file then do something if any of the words were found?
I would like to do something if for example any of these words banana horse window whatever is found within a file.
Here is my last attempt
Dim thefile As String = "C:\application\thefile"
If File.Exists(thefile) Then
Using reader As New StreamReader(thefile)
While Not reader.EndOfStream
Dim line As String = reader.ReadLine()
If line.Contains("Banana") OrElse line.Contains("horse") OrElse line.Contains("window") OrElse line.Contains("whatever") Then
msgbox("Word(s) found " & line)
Do_this_and_that()
Else
MsgBox("Word(s) not found")
Exit While
End If
End While
End Using
Else
msgbox("File not found")
End If
There seem to be so many variations of doing this, but I can't get them to work when its multiple words instead of just one. What is the easies and cleanest way of doing this?

Answer 1

You need to tokenize the line and use a HashSet. That is the fastest method. Put all the words in the HashSet and then check if each word is init:
static void Main()
{
var file = #"C:\application\thefile";
var hashSet = new HashSet<string>(new[] { "banana", "horse", "window", "whatever" }.Select(x => x.ToLower()));
foreach (var word in GetWords(file))
{
Console.WriteLine(word);
if (hashSet.Contains(word))
{
//DoSomething();
Console.WriteLine("\tFound!!");
//Continue or Break;
}
}
}
private static IEnumerable<string> GetWords(string file)
{
var rg = new Regex(#"[^\p{L}]");
const int bufferLen = 512;
using (var reader = File.OpenText(file))
{
var word = new StringBuilder();
while (!reader.EndOfStream)
{
var buffer = new char[bufferLen];
var readChars = reader.ReadBlock(buffer, 0, bufferLen);
for (int i = 0; i < readChars; i++)
{
if (rg.IsMatch(buffer[i].ToString()))//end of the word
{
if (word.Length > 0)
{
yield return word.ToString();
word = new StringBuilder();
}
}
else
word.Append(Char.ToLowerInvariant(buffer[i]));
}
}
if (word.Length > 0)
yield return word.ToString();
}
}
and here in VB
Imports System.Text.RegularExpressions
Imports System.IO
Imports System.Text
Module Module1
Sub Main()
Dim filename = "C:\application\thefile"
Dim words() As String = {"banana", "horse", "window", "whatever"}
Dim bagOfWords = New HashSet(Of String)(words.Select(Function(x) x.ToLower()))
For Each word As String In GetWords(filename)
Console.WriteLine(word)
If bagOfWords.Contains(word) Then
'DoSomething();
Console.WriteLine(vbTab & "Found!!")
'Exit For if you need to terminate here;
End If
Next
End Sub
Private Iterator Function GetWords(filename As String) As IEnumerable(Of String)
Dim rg = New Regex("[^\p{L}]")
Const bufferLen As Integer = 512
Using reader As New StreamReader(filename)
Dim word = New StringBuilder()
While Not reader.EndOfStream
Dim buffer = New Char(bufferLen - 1) {}
Dim readChars = reader.ReadBlock(buffer, 0, bufferLen)
For i As Integer = 0 To readChars - 1
If rg.IsMatch(buffer(i).ToString()) Then
'end of the word
If word.Length > 0 Then
Yield word.ToString()
word = New StringBuilder()
End If
Else
word.Append([Char].ToLowerInvariant(buffer(i)))
End If
Next
End While
If word.Length > 0 Then
Yield word.ToString()
End If
End Using
End Function
End Module

Answer 2

This might be a bit of a performance issue, but you can try using a List(Of String) :
Dim thefile As String = "C:\application\thefile"
Dim toCheck as New List(of String)
'You can fill up your list by whoever you want
toCheck.Add("banana")
toCheck.Add("horse")
'...
Dim FoundWords As New List(Of String)
If File.Exists(thefile) Then
Using reader As New StreamReader(thefile)
While Not reader.EndOfStream
Dim line As String = reader.ReadLine()
'We check our list to see if it matches
For Each item in toCheck
if line.Contains(item) then
FoundWords.Add(item)
End If
Next
End While
End Using
If FoundWords.Count > 0 Then
msgbox(FoundWords.Count.ToString() & " Word(s) found")
Do_this_and_that()
Else
MsgBox("Word(s) not found")
End If
Else
msgbox("File not found")
End If
Now this can be improved but if you don't have thousand of words to look for that should do the trick...