Random file access. reading a struct written from C++

This is not as elegant as reading in a block of bytes and then copying it into a struct, but it will work.  This is a complete sample application.  Just put the file to parse on your C drive with the name "myfile.txt" and then fill in the "/* Use fd here */" section with your processing code.

using System;
using System.IO;

namespace BinaryReadTest {
      public class FlightData_str {
            public string[] dataCell = new string[11];
            public string[] breakoutOrig = new string[10];
            public string[] breakoutConn = new string[10];

            public void ReadFromStream(StreamReader r) {
                  int i;
                  for(i = 0; i < dataCell.Length; i++) {
                        dataCell[i] = ReadFromStream(r, 200);
                  }
                  for(i = 0; i < breakoutOrig.Length; i++) {
                        breakoutOrig[i] = ReadFromStream(r, 10);
                  }
                  for(i = 0; i < breakoutConn.Length; i++) {
                        breakoutConn[i] = ReadFromStream(r, 10);
                  }
            }

            private string ReadFromStream(StreamReader r, int bytes) {
                  if(r.Peek() > 0) {
                        char[] buffer = new char[bytes];
                        r.ReadBlock(buffer, 0, buffer.Length);
                        return new string(buffer);
                  } else {
                        return "";
                  }
            }
      };

      class Flight {
            [STAThread]
            static void Main(string[] args) {
                  using(StreamReader r = new StreamReader("c:\\myfile.txt")) {
                        while(r.Peek() > 0) {
                              FlightData_str fd = new FlightData_str();
                              fd.ReadFromStream(r);

                              /* Use fd here */
                        }
                  }
            }
      }
}

I used this piece of code to read in a struct (a BSP file to be exact. It only had a simple struct, but you should be able to use it, once you get your struct in the proper format:

      public struct BSPHeader
      {
            public int ID;
            public int Version;
      }

And then in a loading method.

      FileStream stream = new FileStream(path, FileMode.Open);

      size = Marshal.SizeOf(typeof(BSPHeader));
      unmanagedByteArray = new IntPtr(0);
      byteArray = new byte[size];
      stream.Read(byteArray, 0, size);
      unmanagedByteArray = Marshal.AllocCoTaskMem(size);
      Marshal.Copy(byteArray, 0, unmanagedByteArray, size);
      Header = (BSPHeader)Marshal.PtrToStructure(unmanagedByteArray, typeof(BSPHeader));
      Marshal.FreeCoTaskMem(unmanagedByteArray);