[fpc-devel] Re: enumerators

[Hans-Peter Diettrich]

Vincent Snijders schrieb:
> 2010/11/14 Thaddy <thaddy at thaddy.com>:
>> On 13-11-2010 20:56, Hans-Peter Diettrich wrote:
>>> The comparison in the UTF-8 string example is very questionable. First
>>> ch(i) is not equivalent to ch, not even closely related, and the claim of
>>> O(N^2) operations deserves an proof - IMO it's simply wrong.
>>>
>> Yes, this caught my eye as well: O(N^2) seems only the case if "length"
>> would be evaluated every time. S
> 
> the O(N^2) stems from the fact that it is hard to get the ith
> character in a a UTF8String in O(1). Suppose it is o(N), then the loop
> is O(n^2).

With regards to UTF-8 (or other MBCS) strings, what does Length(s) 
return in these cases? IMO other functions have to be used for the 
determination of the true character count (as opposed to the char=byte 
count).

At least the example code has to be made work, i.e. the nonsense statement
   DoSomething(ch(i));
has to be changed into something like
   DoSomething(GetUTF8char(s,i));
before we can can talk honestly about the order of the loop.

DoDi