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From: Marco van de Voort <marcov@toad.stack.nl>
Newsgroups: comp.lang.pascal.delphi.misc
Subject: Re: xpost (Sorry) Can someone show me the fix for this please?
Date: Thu, 19 Jul 2012 19:45:05 +0000 (UTC)
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On 2012-07-19, bok <bok.globule@gmail.com> wrote:
>
> The line below of "S:=Reversestring(S)" causes a file full of "nul" to be written instead of S. How do I manipulate S and then correctly write the altered 
> string to n2.exe. 

An empty string might be NIL. Dereferencing NIL might cause an exception.

> Thanks, 
> DBM 
>========================================================= 
>
> procedure TForm1.Button1Click(Sender: TObject); 
> var 
>   readit,writeit: TFileStream; 
>   s: string; 
>   x:integer; 
> begin 
>   readit  := TFileStream.Create('n1.exe', fmOpenread); 
>   writeit := TFileStream.Create('n2.exe', fmCreate or fmOpenWrite); 
>   try 
>     SetLength(s,readit.Size); 
      if length(s)>0
>     readit.Read(PChar(s)^, Length(s)); 
>     s:=reversestring(s);  //<<<<<<-This line is incorrect 
>     writeit.Write(PChar(s)^, Length(s)); 
>   finally 
>     readit.Free; 
>     writeit.Free; 
>   end; 
> end;