Ergebnis der Suchanfrage

• Forum: Object-Pascal / Delphi-Language

  Re: Untyped Binary Files

    Delphi
    by marabu, 21. Feb 2006
  Hi Silvia,
  
  don't panic...
  
  If you decide on a blocksize of 1 byte you must use a read / write count of SizeOf(Integer) - and everything falls in place.
  
  Good Luck
  
  marabu
• Forum: Object-Pascal / Delphi-Language

  Re: Untyped Binary Files

    Delphi
    by marabu, 19. Feb 2006
  One more thing to mention is, you assign a block size when opening the file. You should make a decision:
  
  
  // either
  Reset(Mfile, 1);
  BlockRead(Mfile, tmp, SizeOf(Integer));
  
  // or
  Reset(Mfile, SizeOf(Integer));
  BlockRead(Mfile, tmp, 1);
• Forum: Object-Pascal / Delphi-Language

  Re: Untyped Binary Files

    Delphi
    by marabu, 19. Feb 2006
  Access to address 0 usually happens due to an uninitialized pointer. Try to single step through Button3Click() just to make sure the exception really is thrown there. As the second parameter of BlockRead() is concerned you are doing alright. The procedure signature states the second parameter as an untyped variable, so you can pass in any variable type you like.
  
  marabu
• Forum: Object-Pascal / Delphi-Language

  Re: Untyped Binary Files

    Delphi
    by marabu, 19. Feb 2006
  Hi Silvia,
  
  it is good practice to close a file before reopening it - there is a CloseFile() missing in your OnClick handler for Button1. There seems to be no further problem with your code, means it performs as intended on my machine. Can you point out the very line of code that throws the exception?
  
  BTW: Modern times file i/o is done with filestreams. You might want to read about it in the...