Colin, the for C in loop and the for i := 1 to Length() loops are functionally identical! The only difference is that the for in version incurs the slight overhead of the enumerator framework invoked by the compiler and runtime magic to support that syntax.
But in neither case will the loop itself help detect/respond to surrogate pairs (a single WideChar is potentially only ½ the data required to form a complete character). The only way to reduce an iterator over a string to a simple char-wise loop, whether explicit or using enumerators, is to first convert to UTF32, the facilities for which in the Delphi RTL are <cough> rudimentary, to put it politely. Non-existent may be nearer the mark. The precise mechanics of the loop construct used is not material to that problem. However, just as before Unicode when most people didnt care and just wrote code that assumed ANSI==ASCII, these days people wont care and will write code that assumes that Unicode==BMP (Basic Multilingual Plane), ignoring surrogate pairs just as they used to ignore extended ASCII and ANSI characters. And for most people, that will probably actually work. J From: delphi-boun...@delphi.org.nz [mailto:delphi-boun...@delphi.org.nz] On Behalf Of Colin Johnsun Sent: Tuesday, 23 November 2010 14:31 To: NZ Borland Developers Group - Delphi List Subject: Re: [DUG] Upgrading to XE - Unicode strings questions I won't answer everything but just on this one question: On 23 November 2010 11:04, John Bird <johnkb...@paradise.net.nz> wrote: Extra question: It looks like code like for i:=1 to length(string1) do begin DoSomethingWithOneChar(string1[i]); end; cannot be used reliably. The problems are that length(string1) looks like it cannot be safely used - as unicode characters may include 2 codepoints and length(string1) highlights that there is a difference between the number of unicode characters in a string and the number of codepoints. Still figuring out what is the best practice here, as I have quite a lot of string routines. Should be be OK as long as the unicode text actually is ASCII. you can use something like this: var C: Char; ... for C in String1 do begin DoSomethingWithOneChar(C); end; In this case you don't need to know the index of each character, you just get the char using the for..in..do loop.
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