Limit to FileSize function

[Balchy]

It appears there is a limit to the FileSize function in Delphi 6. The function returns a 4 byte integer that reports incorrect file sizes for very large files (e.g. on DVDs). Has this changed in Delphi 7 (say Filesize:integer, to Filesize:Int64)?

 

[towerbase]

The Size function in the TStream (and hence TFileStream) class returns an Int64 in Delphi 7. It returns a LongInt (31 bit signed integer) in Delphi 5. I haven't got Delphi 6.

Andrew

 

[Balchy]

Thanks towerbase. Delphi 6 has Tstream and hence TFileStream. The following code worked on a 3.3 Gbyte file.

function BigFileSize(Filename:string):Int64;
var
BigFileStream : TFileStream;
begin
BigFileStream := TFileStream.Create(Filename, fmOpenRead);
BigFileSize := BigFileStream.Size;
BigFileStream.Free;
end;

Now I'm tracing back my Integers and replacing with Int64.
Thanks again,
Balchy

 

[towerbase]

I'm surprised your BigFileSize function worked because it doesn't seem to be returning a value in result. It's also considered good practice to use try..finally constructs when allocating resources.

function BigFileSize(FileName: string): Int64;
begin
  with TFileStream.Create(FileName,fmOpenRead) do try
    result := Size;
  finally
    free;
  end;
end;

 

[Stretchwickster]

Balchy's function is returning a value. You can return a value from a function by assigning a value to the function itself i.e.

  BigFileSize := BigFileStream.Size;

is equivalent to:

  Result := BigFileStream.Size;

But the preferred method is to use "Result". Clive

http://www.kucu.co.uk

Ex nihilo, nihil fit (Out of nothing, nothing comes)

 

[towerbase]

Quite right, Clive. I'm so used to assigning to result I forgot about the original Pascal way of returning values.

Andrew