Passing back a String with Pchar array 1

[robdon]

Hi,

I am new to Delphi, so sorry if this is a 'newbie' question ... pointers just confuse me at the moment.

I have a proc, that passes an array of pointers, and I cannot figure out how to pass back a string, and I've tried the following but it wont compile.

type
TPCharArray = array[0..12] of PChar;

function ReadFileToArray(argc: ShortInt; var argv: TPCharArray): integer; stdcall; export;
var strRob : String;
Begin
strRob := 'robdon'#0;
argv[3] := Pchar(strRob);
End;

If I change the code to
argv[3] := 'robdon'#0;
It works fine, but I want to pass back a variable, that has a string in it.

I cant change the parameters to the proc, cause its a DLL that is called by a 3rd party app.

Thanks for any help,

Rob Donovan.

ProIV Resource Centre

http://www.proivrc.com

 

[Zathras]

What is the error?
What version of Delphi?

I just pasted your code into a D7 app and it compiled ok for me.

 

[robdon]

Hi,

That was quick

My mistake sorry.

I was copying code between Delphi and FreePascal, and it was in FreePascal that I got the error, not Delphi, it was 'Illegal type conversion'.

I guess I should ask somewhere else for pascal questions, sorry, but thanks for the fast respone anyway.

Rob.

ProIV Resource Centre

http://www.proivrc.com

 

[Glenn9999]

Actually what you did is not the best thing in both cases. Delphi is just being freer from what i can see. Though what you posted compiles in FreePascal 2.0.2.

Proper way to do your code is:

  var strRob : String;
Begin
  strRob := 'robdon';
  argv[3] := Pchar(strRob);
end;

The PChar type cast will take the Pascal string and convert it to PChar type, which will include the #0 null terminator.

Question: Are you using Delphi mode on FreePascal "-sD"? Perhaps that's your trouble?

 

[robdon]

Hi,

Thanks for the post, that got me on the right tracks.

The version of Pascal I had downloaded was a very old one, version 1.x

I upgraded to 2.0.2 and then the code compiled fine.

However, the -sD switch did not work, but I ended up using -Mdelphi

Thanks again.

Rob D.

ProIV Resource Centre

http://www.proivrc.com