[DUG] Upgrading to XE - Unicode strings questions

[John Bird]

Planning upgrading from D2007 to XE, but want to read up on issues I will 
need to consider first to do with strings becoming Unicode by default.   I 
recall the release of D2009 came with good white papers explaining 
ramifications, however I haven’t seen these as I haven’t upgraded.   Asked 
for such also at the XE event but have not been sent anything yet.

I have a lot of code which I want to plan to be able to recompile easily, 
and would like to plan this migration.   I would prefer to put anything 
contentious or varying into a library unit, a ‘wrapper’ so that I don’t have 
to deal with these version differences in the main code...

Anyone can answer any of these quick questions please post here or email 
me – thanks!

Q1 - Anyone got some good references to read up on ansistring to unicode 
issues ?  Comprehensive please!

Q2 – With XE do the .pas and .dfm files become unicode text and hence cannot 
be read by earlier Delphi, eg D2007 any more?

Q3 – I do a lot of reading ascii data files, and writing back.   Using 
mainly TFilestream and stringlists.   Does this in general mean I will need 
to use file variables declared as Ansichar and AnsiString instead of Char 
and String?
(I would prefer to use the standard VCL where possible)

If I have variables
        as1:Ansistring;
        s2:string;

Q4 –         if I do s2:=as1  does this convert ansistrings to unicode?

Q5 – if I do as1:=s2 does this convert a unicode string to ansstring?

    (otherwise how do I do this?)

Q6 – I understand any code like

            char1:=string1[i];
            if char1 in [‘a’..’z’] then
            begin
                    message:=string[i]+’ - character is lowercase’;
            end

        will break, as ansi characters are ordinal (less than 256 or 512) 
and set comparisons ['a'..'z']  or ['a','b','c']    can be used, this set 
code cannot be used for unicode characters.   What is the replacement?


Q7 – do literals like  #13#10 still mean carriage return and linefeed?  #9 
means tab?
        if I have code like (logline string1 string2 are string)

        logline:=FormatDateTime(‘dd-mmm-yyyy hh:nn:ss’,now) + string1 + 
#13#10+#9 + string2;
        ShowMessage(logline);
        Button1.hint:=logline;
        writeln(f,logline);

        these work D5-D2007   - ie a 2 line messagebox text, 2 line hint, 
and 2 lines written to a log file.
        is this still going to work?

        do carriage returns/tabs/other control characters have to be defined 
differently, eg as constants?

Q8 – stringlist1.loadfromfile(‘Test1.txt’);
        what happens if this file is ascii text being read into a stringlist 
which is unicode strings.

Q9 -   stringlist1.savetofile(‘Test1.txt’)
         presumably this is no longer ascii text.   How do I save and read a 
stringlist to/from a file if it is to be Ansi text?

Q10 – If there are complexities in Q8 and Q9 is there a TAnsiStringlist 
type (for ansistrings) as well as a unicode TStringlist type?
        (I use stringlists a lot)

Q11 – do inifiles become unicode too?

Q12 – does Windows Notepad open unicode text files correctly?   or can it 
only be used on Ansi text files?

Q13 - It looks like most programmers editors read and write ascii and 
unicode encoding.....the one I use seems to distinguish between UTF-8 and 
unicode as well – what is the difference?

John