Hi,

When I use "copy" on a PChar (e.g. copy(p,1,1)), it is very slow, because the compiler converts the PChar to a string.

Is there already a function for PChar?

Can an overloaded version of copy be added?

Mattias

19.02.2012 18:38, Mattias Gaertner пишет:

Not sure why it is allowed in the first place. If out of Delphi compatibility, maybe we should leave it enabled for {$mode delphi} only (should be possible because copy is partially handled by compiler).

Is there already a function for PChar? Can an overloaded version of copy be added?

It is a question how to interpret indices then (PChar is zero-based while strings are 1-based). And actually it will mean 4 overloads: PChar, PWideChar, array of char, array of widechar.

Regards,
Sergei

In our previous episode, Mattias Gaertner said:

When I use "copy" on a PChar (e.g. copy(p,1,1)), it is very slow, because the compiler converts the PChar to a string. Is there already a function for PChar?

http://www.freepascal.org/docs-html/rtl/strings/strlcopy.html

It's a useful feature.

Indeed. That would be confusing.

Is there already a function

function Copy(StartPos: PChar; Count: PtrUInt; StopAt0: boolean =
true): string;

Mattias

Thanks. But apparently I was not exact enough.

"Copy" has the nice feature, that the bounds are checked. For PChar it does that too, but it always runs through the whole PChar to #0.
And I need an Ansistring as result.

Mattias

19.02.2012 20:34, Mattias Gaertner пишет:

I don't know about an already existing such function (well, actually SetString used to work that way in the past, but no longer), but here's one (assuming StartPosnil):

var
   len: sizeint;
begin
   if StopAt0 then
   begin
     len:=IndexByte(StartPos^,Count,0);
     if len=-1 then
       len:=Count;
   end
   else
     len:=Count;
   SetString(result,StartPos,len);
end;

Regards,
Sergei

In our previous episode, Mattias Gaertner said:

http://www.freepascal.org/docs-html/rtl/system/setstring.html

How should it work ?
A Phar as a left value sets the pointer to some (hopefully sensible) memory location. for a string resulting from "copy" such memory would need to be allocated.

IMHO implicitly doing a malloc() and propagate the need to free the memory allocation to the user is very ambiguous.

-Michael