BlockRead not working with dynamic arrays

[Joseph I. Ceasar]

Hi all,

I am using a dinamic array with block read and I keep on geting an I/O error
87. When I replace the dynamic array for a static one, then everything
works just fine. The problem is, I need to use that dynamic array.

Here is a piece of the code:

procedure Sort_UnzipFiles();
var WordBuf: array of char;
begin
S:=SearchZip.Name;
SetLength(WordBuf,50000);
AssignFile(WordFile, '\aaa\' + S);
Reset(WordFile, 1);
I:=Length(WordBuf);
BlockRead(WordFile, WordBuf, I, FileLength);
CloseFile(WordFile);
.
.
.
end; {Sort_UnzipFiles}

Any ideas?

--
------------------------------------------------------------
Joseph I. Ceasar
Senior Project Manager and IT/IS Administrator
Silent Type, Inc.
------------------------------------------------------------

[Rudy Velthuis (TeamB)]

In article <3aef04d4_2@dnews>, Joseph I. Ceasar says...

> var WordBuf: array of char;

...
> SetLength(WordBuf,50000);
...
> BlockRead(WordFile, WordBuf, I, FileLength);

> Any ideas?

WordBuf is a dynamic array, so WordBuf only contains a pointer to the
actual array. The actual array starts at WordBuf[0] (actually, this means
WordBuf^[0], but that is not valid syntax here). You could use:

BlockRead(WordFile, WordBuf[0], I, FileLength);

--
Rudy Velthuis (TeamB)

[Martin Lafferty]

> I am using a dinamic array with block read and I keep on geting an I/O
error
> 87. When I replace the dynamic array for a static one, then everything
> works just fine. The problem is, I need to use that dynamic array.
>
> Here is a piece of the code:
>
> procedure Sort_UnzipFiles();
> var WordBuf: array of char;
> begin
> S:=SearchZip.Name;
> SetLength(WordBuf,50000);
> AssignFile(WordFile, '\aaa\' + S);
> Reset(WordFile, 1);
> I:=Length(WordBuf);
> BlockRead(WordFile, WordBuf, I, FileLength);
> CloseFile(WordFile);
> .

A dynamic array variable is actually a pointer, whereas a static array is a
variable. I am sure there is a correct way to do this (and this isn't it),
but I would cast the reference into a pointer then deference it thus:

BlockRead(WordFile, Pointer(WordBuf)^, FileLength)

regards

Martin Lafferty