speed boost

V 0

Hi there, We're having a small test here at work. Read in a text file and convert half the text to uppercase as quickly as possible ("aabb" => "aAbB", so not "AAbb") So I read in the text file and do a for with i+=2 instead of i++ and setting a Stringgbuilder. after the text is done I put text into the text box. Then I use ngen to boost speed a bit (compiler is set to optimized etc.) I also tried to use SuspenLayout and ResumeLayout, but that didn't gain me a lot. Any other tricks I can use to boost this up? (maybe I forgot to set some compiler options or I have to do it in another way? here's my code:

   System.IO.StreamReader reader = new System.IO.StreamReader(openfiledlg.FileName);
   text = new StringBuilder(reader.ReadToEnd());
   reader.Close();
   pb\_conversion.Maximum = text.Length;
   starttime = DateTime.Now;
   //Starting from 1 will gain me 1 character less to analyze.
   for(int i = 1; i < text.Length; i+=2){
       text\[i\] = text\[i\].ToString().ToUpper()\[0\];
       pb\_conversion.Value = i;
   }					//end for
   txtbox\_result.Text = text.ToString();
   difference = DateTime.Now - starttime;
   lbl\_result.Text = "Done in: " + difference.TotalMilliseconds + " milliseconds.";
   lbl\_result.Visible = true;

I'm curious what else I could do... thanks.

V. I found a living worth working for, but haven't found work worth living for.

althamda

You could go through the text as a char array and just subtract 32 from each other char to get uppercase. Might be a little faster.

Christian Graus

I reckon the ToString is probably expensive. Just deal with chars, instead. You can use Char.IsLower to find out if a char is a lower case letter, or just use Char.ToUpper to convert it.

Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog "I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

V 0

thanks for the reply. I'm around 81 seconds with a 20 Mb file. (84 first)

V.
Stop smoking so you can: Enjoy longer the money you save. Moviereview Archive

Pete OHanlon

I had a play round with this, and got a 21 MB file to process in about 10 seconds. This code isn't perfect, but it is a decent basis to carry on with:

public void ReadFile()
{
  if (openfiledialog.ShowDialog() == DialogResult.OK)
  {
    System.IO.StreamReader reader = new System.IO.StreamReader(openfiledialog.FileName); 
    StringBuilder text1 = new StringBuilder(reader.ReadToEnd()); 
    reader.Close(); 
    pb_conversion.Maximum = text1.Length; 
    DateTime starttime = DateTime.Now; 
    //Starting from 1 will gain me 1 character less to analyze. 
    int innercount = 0;
    for(int i = 1; i < text1.Length; i+=2)
    { 
      text1[i] = text1[i].ToString().ToUpper()[0];
      if (++innercount == 1000)
      {
        innercount = 0;
        pb_conversion.Value = i; 
      }
    }
    txtbox_result.Text = text1.ToString();
    TimeSpan difference = DateTime.Now - starttime;
    MessageBox.Show(difference.ToString());
  }
}

One of the key areas is that you no longer attempt to update the progress bar every iteration. This is just wasteful and should be avoided - which is why I update every 1000 iterations.

Deja View - the feeling that you've seen this post before.

V 0

dude, I couldn't believe my eyes when I saw the difference :omg: 11 seconds ! thanks man.

V.
Stop smoking so you can: Enjoy longer the money you save. Moviereview Archive

Pete OHanlon

Glad to be of service.:-D

Deja View - the feeling that you've seen this post before.

althamda

Wouldn't using a char[] be faster than using a StringBuilder? char[] c = sr.ReadToEnd().ToCharArray(); for (int i = 0; i < c.Length; i+=2) { c[i] = (char)((int)c[i] - 32); }

Pete OHanlon

It would, but you need to enclose the c[i] test with an if (char.IsLetter(c[i])... so that you don't end up converting none alphabetic characters.

Deja View - the feeling that you've seen this post before.