how to write to file that is open

Question

My program writes to a file.

The user can needs to be able open file read it.

This gives an error, when trying add more data to file

This is for C#

Answer 1

If one program opens a binary file in this manner:

FileStream s = new FileStream( @"C:\MyFiles\file1.bin", 
   FileMode.OpenOrCreate, FileAccess.Write, FileShare.ReadWrite);

s.Write( . . . );
s.Flush();

then another program can read it:

FileStream s = new FileStream( @"C:\MyFiles\file1.bin", 
   FileMode.Open, FileAccess.Read, FileShare.ReadWrite );

s.Read( . . . );