Extremely Large Single-Line File Parse

by

That’s an extremely inefficient way to read a text file, let alone a large one. If you only need one pass, replacing or adding individual characters, you should use a StreamReader. If you only need one character of lookahead you only need to maintain a single intermediate state, something like:

enum ReadState
{
    Start,
    SawOpen
}


using (var sr = new StreamReader(@"path\to\clinic.txt"))
using (var sw = new StreamWriter(@"path\to\output.txt"))
{
    var rs = ReadState.Start;
    while (true)
    {
        var r = sr.Read();
        if (r < 0)
        {
            if (rs == ReadState.SawOpen)
                sw.Write('<');
            break;
        }

        char c = (char) r;
        if ((c == '\r') || (c == '\n'))
            continue;

        if (rs == ReadState.SawOpen)
        {
            if (c == 'C')
                sw.WriteLine();

            sw.Write('<');
            rs = ReadState.Start;
        }

        if (c == '<')
        {
            rs = ReadState.SawOpen;
            continue;
        }

        sw.Write(c);
    }
}

More Related Contents:

  1. Easiest way to read from and write to files
  2. How do I read a specified line in a text file?
  3. How to read an entire file to a string using C#?
  4. c# search string in txt file
  5. Using StreamReader to check if a file contains a string
  6. Reversing the given string without using reverse function [closed]
  7. Why does Read interfere with ReadLine? [duplicate]
  8. Parsing CSV files in C#, with header
  9. FileSystemWatcher vs polling to watch for file changes
  10. Easiest way to split a string on newlines in .NET?
  11. Converting string to title case
  12. Most efficient way to remove special characters from string
  13. Converting string to double in C#
  14. Replace Multiple String Elements in C#
  15. How to remove all white space from the beginning or end of a string?
  16. Find Nth occurrence of a character in a string
  17. Replacing a char at a given index in string? [duplicate]
  18. Encode a FileStream to base64 with c#
  19. How does StringBuilder work internally in C#?
  20. Can I simply ‘read’ a file that is in use?
  21. Display Float as String with at Least 1 Decimal Place
  22. Delete last char of string
  23. Why is \ character being doubled in my @ string?
  24. string.Join on a List or other type
  25. How to sort list of Ip Addresses using c#
  26. String comparison – strA.ToLower()==strB.ToLower() or strA.Equals(strB,StringComparisonType)?
  27. Regular expression to find and remove duplicate words
  28. How can I safely convert a byte array into a string and back? [duplicate]
  29. Does any one know of a faster method to do String.Split()?
  30. How do i replace accents (german) in .NET

Leave a Comment