On Tue, 21 Jun 2005, Marc Santhoff wrote:
> Hi,
>
> in an application of mine occurs a lot of string separation and
> re-concatenation. Since it is using masses of ANSI strings this is some
> performance problem.
>
> The strings get stored and loaded from TStringList's and concatenated
> by simply using '+' and separated with the function copy().
>
> What I'd like to know is: What's are fastest ways of handling ANSI
> strings?
It's hard to say in general; You would have to supply some example code.
if you're doing things like
For I:=X to Y do
S:=S+L[i]; // S string, L list.
then
It might be better to do
Len:=0;
For I:=X to Y do
Inc(Len,Length(L[i])); // S string, L list.
SetLength(S,Len);
P:=1;
For I:=X to Y do
begin
T:=L[i];
Len:=Length(T);
Move(T[1],S[P],Len);
inc(P,Len)
end;
This will avoid a lot of calls to uniquestring, get/setlength etc.
Also, keep in mind that getting the I-th string from a list is an expensive
operation.
So it is better to do
T:=L[i];
S:=Copy(T,X,Length(T)-X);
than to do
S:=Copy(L[i],X,Length(L[i])-X);
The first option will call GetString only once, the second will call it twice.
This is the kind of thing you should pay attention to.
Michael.
_______________________________________________
fpc-pascal maillist - fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal
