Question

I need to know is there some string at exact location on the .txt file.
I know how to found concrete string with Contains method, but since I do not need to search whole file (string will always be on the same location) I’m trying to find quickest solution.

if (searchedText.Contains(item))
{
   Console.WriteLine("Found {0}",item);
   break;
}

Thanks

Answer 1

If it’s in UTF-8 and isn’t guaranteed to be ASCII, then you’ll just have to read the relevant number of characters. Something like:

 using (var reader = File.OpenText("test.txt"))
 {
     char[] buffer = new char[16 * 1024];
     int charsLeft = location;
     while (charsLeft > 0)
     {
         int charsRead = reader.Read(buffer, 0, Math.Min(buffer.Length,
                                                         charsLeft));
         if (charsRead <= 0)
         {
             throw new IOException("Incomplete data"); // Or whatever
         }
         charsLeft -= charsRead;
     }
     string line = reader.ReadLine();
     bool found = line.StartsWith(targetText);
     ...
 }

Notes:

• This is inefficient in terms of reading the complete line starting from the target location. That’s simpler than looping to make sure the right data is read, but if you have files with really long lines, you may want to tweak this.
• This code doesn’t cope with characters which aren’t in the BMP (Basic Multilingual Plane). It would count them as two characters, as they’re read as two UTF-16 code units. This is unlikely to affect you.