Count substring occurrence

Question

I have a text file called info.txt with string in it.

info.txt

05331
02555
03211
05222
04321
02387
03444
03127
05117
03680
03881
01579
03111

My output should be in new.txt

Output new.txt

05331
02555
03211
1
05222
04321
02387
03444
03127
2
05117
03680
03881
01579
03111
3

Basically I should get the count of all strings starting with "03" and print the count before the substring "01"

       try
       {
           String line;
           Int counter =0;
           StreamReader sr = new StreamReader("C:\\Files\\gamenam.txt");
           StreamWriter sw = new StreamWriter("C:\\Files\\gamenam_1.txt");

           while ((line = sr.ReadLine())!= null)
           {
               if (line.substring(0,2) == "05")
               {
                   sw.Write(counter.ToString());
                   counter =0;
               }
               If (line.subString(0,2) =="03")
               {
                   //loop
                   counter++;
               }

               sw.WriteLine(line);
           }

           sr.Close();
           sw.Close();
       }
       catch (Exception e)
       {
           Console.WriteLine("Exception: " + e.Message);
       }
       finally
       {
           Console.WriteLine("Exception finally block.");
       }
   }

After writing my code I could only get.

0
05331
02555
03211
1
05222
04321
02387
03444
03127
2
05117
03680
03881
01579
03111

The 0 on the first line shouldn't be the since I have no stings before and there is no count for last count.

Please help guys.

Answer 1

Instead of your while loop you can try something like that:

...
Boolean isFirstLine = true;

while ((line = sr.ReadLine()) != null) {
  // If line starts with "05" we should print out counter 
  // (that is number of "03" started lines)
  // unless it is the first line in the file
  if (line.StartsWith("05")) {
    if (!isFirstLine)
      sw.WriteLine(counter.ToString()); 

    sw.WriteLine(line); 
    counter = 0;  
    isFirstLine = false; 

    continue;
  }

  sw.WriteLine(line);

  if (line.StartsWith("03")) 
    counter += 1;

  // We should also print out counter after the last file line
  // if, say, counter > 0 
  if (sr.Peek() < 0) // <- No next line
    if (counter > 0)
      sw.WriteLine(counter.ToString());

  isFirstLine = false;
}
...

Answer 2

Here's code for using a READ AHEAD implementation. Just before the end of the loop, you read the next line, if it is null (end of file) or it starts with "05" then you output and reset counter

            try
            {
                int counter = 0;
                //Pass the file path and name to the StreamReader constructer
                StreamReader sr = new StreamReader("gamenam.txt");
                //Pass the file path and name to the StreamReader constructer
                StreamWriter sw = new StreamWriter("gamenam_1.txt");


                string line = sr.ReadLine();
                while (line != null)
                {
                    if (line.Substring(0, 2) == "03")
                    {
                        counter++;
                    }

                    sw.WriteLine(line);

                    line = sr.ReadLine();
                    if ((line == null) || (line.StartsWith("05")))
                    {
                        sw.WriteLine(counter.ToString());
                        counter = 0;
                    }
                }

                //Close
                sr.Close();
                sw.Close();
            }
            //Catching exception
            catch (Exception e)
            {
                //Exception Message
                Console.WriteLine("Exception: " + e.Message);
            }
        }
        finally
        {
            Console.WriteLine("Exception finally block.");
        }

Answer 3

Thanks for all you r help guys, from all you input, I finally got the output I needed.

I wrote my code like this

       String line;
       int counter = 0;
       Boolean isFirstLine = true;
       try
       {
           StreamReader sr = new StreamReader("C:\\Files\\gamenam.txt");
           StreamWriter sw = new StreamWriter("C:\\Files\\gamenam_1.txt");

           while ((line = sr.ReadLine()) != null)
           {
               if (line.Substring(0, 2) == "01")
               {
                   if (!isFirstLine)
                   {
                       sw.WriteLine(counter.ToString());
                       counter = 0;  
                   }
               }
               if (line.Substring(0, 2) == "05")
               {
                   counter++;
               }
               sw.WriteLine(line);
               if (sr.Peek() < 0)
               {
                   sw.Write(counter.ToString());
               }
               isFirstLine = false;
           }
           sr.Close();
           sw.Close();
       }