Binary file I/O (I hate you!)

[Scott Penner]

Has anyone had any luck with binary file I/O?

I'm used to the good ole VB syntax...You know create a few structs for the headers and an array for the data. Then, read them in...It's like 6 lines (including the open and close).

Actually this is about the same in C++. So, why is this so dang obscure in C#? Or am I just slow (this is altogether possible).

I would like find an intelligent to read and write binary data (read not serialization) that is "Safe" in the .net sense. The biggest problem I've come accross so far is trying to read in a structure with what should be a fixed string:

struct MakeBelieveStructure
{
   public string MyName;  // should be 20 characters
   public string MyAddress;  // should be 100 characters
   public int[] MyNumbers;  // List of 20 integers
}
// What I would like to do...
BinaryReader  MyReader = new BinaryReader();
MakeBelieveStructure MyStruct;
MyStruct = MyReader.Read(sizeof(MakeBelieveStructure)); 

I've tried to explicitly define the structure, and to use pointers ( which work fine for fixed structure sizes ) but it just doesn't seem easy. And I haven't found a "Safe" way to do it yet....

any ideas?

[kovan]

this migh thelp

The BinaryWriter and BinaryReader classes are used for writing 
and reading data, rather than character strings. The following 
code example demonstrates writing data to and reading data 
from a new, empty file stream (Test.data). After creating the data 
file in the current directory, the associated BinaryWriter and 
BinaryReader are created, and the BinaryWriter is used to write 
the integers 0 through 10 to Test.data, which leaves the file 
pointer at the end of the file. After setting the file pointer back to 
the origin, the BinaryReader reads out the specified content.

[Visual Basic]
Option Explicit
Option Strict
Imports System
Imports System.IO
Class MyStream
   Private Const FILE_NAME As String = "Test.data"
   Public Shared Sub Main()
      ' Create the new, empty data file.
      If File.Exists(FILE_NAME) Then
         Console.WriteLine("{0} already exists!", FILE_NAME)
         Return
      End If
      Dim fs As New FileStream(FILE_NAME, FileMode.CreateNew)
      ' Create the writer for data.
      Dim w As New BinaryWriter(fs)
      ' Write data to Test.data.
      Dim i As Integer
      For i = 0 To 10
         w.Write(CInt(i))
      Next i
      w.Close()
      fs.Close()
      ' Create the reader for data.
      fs = New FileStream(FILE_NAME, FileMode.Open, FileAccess.Read)
      Dim r As New BinaryReader(fs)
      ' Read data from Test.data.
      For i = 0 To 10
         Console.WriteLine(r.ReadInt32())
         w.Close()
      Next i
   End Sub
End Class
[C#]
using System;
using System.IO;
class MyStream {
   private const string FILE_NAME = "Test.data";
   public static void Main(String[] args) {
      // Create the new, empty data file.
      if (File.Exists(FILE_NAME)) {
         Console.WriteLine("{0} already exists!", FILE_NAME);
         return;
      }
      FileStream fs = new FileStream(FILE_NAME, FileMode.CreateNew);
      // Create the writer for data.
      BinaryWriter w = new BinaryWriter(fs);
      // Write data to Test.data.
      for (int i = 0; i < 11; i++) {
         w.Write( (int) i);
      }
      w.Close();
      fs.Close();
      // Create the reader for data.
      fs = new FileStream(FILE_NAME, FileMode.Open, FileAccess.Read);
      BinaryReader r = new BinaryReader(fs);
      // Read data from Test.data.
      for (int i = 0; i < 11; i++) {
         Console.WriteLine(r.ReadInt32());
         w.Close();
      }
   }
}
If Test.data already exists in the current directory, an IOException is thrown. Use FileMode.Create to always create a new file without throwing an IOException.