Question

I need some logic/programming help with reading more than one record from a text file. I can read line for line, but I need to stop as soon as the record is finished, push that object to a list, and then continue with a new record until the next one comes up, save to list, etc…

The header of the record always start with G as the first char. The rest if V (Variable), D (Coordinates), M (Insertion Point), etc…

The file contents looks like this: (dummy data)

G FEATURE01 LEVEL01
M -10.5132 10.0000 697.5086
V \~\@ENTITY=LINE 
V \~\@PENSTYLE=0
V \~\@PENTHICK=1
D -10.5089 12.0797 697.8155
D -10.4971 13.6198 698.0429
D -10.0399 17.3069 698.5913
D -10.7665 11.6108 699.2279
D -10.6769 15.9840 699.8735
D -10.8229 13.6024 710.4438
G FEATURE02 LEVEL02
M -10.2681 10.0000 700.4186
V \~\@ENTITY=LINE
V \~\@PENSTYLE=0
V \~\@PENTHICK=1
D -10.2269 10.6946 700.4941
D -10.2585 13.1788 700.7637
D -10.2937 15.9480 701.0642
D -10.9494 20.5230 709.1840
D -10.9277 21.4909 709.4517
D -10.8335 23.3862 709.9763
G FEATURE01 LEVEL02
M -15.4500 10.0000 700.4174
V \~\@ENTITY=LINE 0.00 0 0.00 A A
V \~\@PENSTYLE=0 0.00 0 0.00 A A
V \~\@PENTHICK=1 0.00 0 0.00 A A
D -15.5690 12.3042 700.6673
D -15.3502 14.3130 700.8863
D -15.1219 16.7179 701.1480
D -15.0628 17.3409 701.2427
D -15.5481 20.8968 709.2855
D -15.3132 22.9163 709.8470
D -15.1355 23.2957 709.9627
G FEATURE03 LEVEL03
P 0.0000 0.0000 0.0000 270.0000 90.0000
M -12.8612 14.2951 737.6336
V \~\@ENTITY=LINE
V \~\@PENSTYLE=1
V \~\@PENTHICK=1
V @0ver1ay=KOOS
D -13.2715 15.5321 736.5965

So, as from above there is 4 records in the text file.
Any ideas?
Thanks

Answer 1

Here is a piece of code that I have tried to put together for clarity rather than robustness etc. it should put you on the right track.

1- I created a simple record class which will be created for each record (lines starting with ‘G’) and then all subsequent lines are added to this record until a new start of record is encountered in the file.

class Record
{
  public List<string> Lines { get; private set; }
  public Record()
  {
    Lines = new List<string>();
  }
}

2- Then the following code will process the file line by line, creating new records as they occurr and adding each record to a Record collection.

  // Collection to be populated with the record data in the file
  List<Record> records = new List<Record>();

  using (FileStream fs = new FileStream("datafile.dat", FileMode.Open))
  using (StreamReader rdr = new StreamReader(fs))
  {
    string line;

    // Read first line
    line = rdr.ReadLine();
    while (line != null)
    {   
      // Check if we have a new record
      if (line.StartsWith("G"))
      {
        // We have a start of a record so create an instance of the Record class
        Record record = new Record();

        // Add the first line to the record
        record.Lines.Add(line);

        // Read the next line
        line = rdr.ReadLine();

        // While the line is not the start of a new record or end of the file,
        // add the data to the current record instance
        while (line != null && !line.StartsWith("G"))
        {
          record.Lines.Add(line);
          line = rdr.ReadLine();
        }

        // Add the record instance to the record collection
        records.Add(record);
      }
      else
      {
        // If we get here there was something unexpected
        // So for now just move on and read the next line
        line = rdr.ReadLine();
      }
    } 
  }