Delphi 2009 + Unicode + Char-size


I just got Delphi 2009 and have previously read some articles about modifications that might be necessary because of the switch to Unicode strings.
Mostly, it is mentioned that sizeof(char) is not guaranteed to be 1 anymore.
But why would this be interesting regarding string manipulation?

For example, if I use an AnsiString:='Test' and do the same with a String (which is unicode now), then I get Length() = 4 which is correct for both cases.
Without having tested it, I'm sure all other string manipulation functions behave the same way and decide internally if the argument is a unicode string or anything else.

Why would the actual size of a char be of interest for me if I do string manipulations?
(Of course if I use strings as strings and not to store any other data)

Thanks for any help!

Best Solution

With Unicode SizeOf(SomeChar) <> Length(SomeChar). Essentially the length of a string is less then the sum of the size of its chars. As long as you don't assume SizeOf(Char) = 1, or SizeOf(SomeString[x]) = 1 (since both are FALSE now) or try to interchange bytes with chars, then you shouldn't have any trouble. Any place you are doing something creative stuffing Bytes into Chars or Strings, then you will need to use AnsiString.

(SizeOf(SomeString) is still 4 no matter the length since it is essentially a pointer with some compiler magic.)