OpenEuphoria

Re: Writing records into fixed length record file....

• Posted by Derek Parnell <ddparnell at bigpond.com> Aug 11, 2004
• 400 views

John F Dutcher wrote:
> 
> 
> Will it probably be my misfortune to discover that I cannot use puts()
> to write a string into a fixed length file (as in update or replace data)
> because puts() will append a trailing character(s) and mess up the file.
> Looping thru putc() is kind of undesireable for many records. 
> There seems to be no counter-part to 'get_bytes' to do writes to a 
> fixed length file with fixed length records .... i.e. 'put_bytes' ??

Actually you *can* use puts() to do this. 

  fh = open("thefile.dat", "ub")
  . . .
  pos_to_update = (recnum - 1) * recsize
  VOID = seek(fh, pos_to_update)
  newrec = get_bytes(fh, recsize)  -- Read in existing record.
  newrec[x..y] = whatever --- Fill in the 'fields' in the record.
  . . .
  VOID = seek(fh, pos_to_update)
  puts(fh, newrec)

  
-- 
Derek Parnell
Melbourne, Australia