string – Check if MyString[1] is an alphabetical character? – Stack Overflow (and how Embarcadero broke one of the product version neutral redirects)

Quite a while ago [Wayback/Archive] string – Check if MyString[1] is an alphabetical character? – Stack Overflow asked by [Wayback/Archive] User Jeff was answered by [Wayback/Archive] Andreas Rejbrand:

The simplest approach is

function GetAlphaSubstr(const Str: string): string;
const
  ALPHA_CHARS = ['a'..'z', 'A'..'Z'];
var
  ActualLength: integer;
  i: Integer;
begin
  SetLength(result, length(Str));
  ActualLength := 0;
  for i := 1 to length(Str) do
    if Str[i] in ALPHA_CHARS then
    begin
      inc(ActualLength);
      result[ActualLength] := Str[i];
    end;
  SetLength(Result, ActualLength);
end;

but this will only consider English letters as “alphabetical characters”. It will not even consider the extremely important Swedish letters Å, Ä, and Ö as “alphabetical characters”!

Slightly more sophisticated is

function GetAlphaSubstr2(const Str: string): string;
var
  ActualLength: integer;
  i: Integer;
begin
  SetLength(result, length(Str));
  ActualLength := 0;
  for i := 1 to length(Str) do
    if Character.IsLetter(Str[i]) then
    begin
      inc(ActualLength);
      result[ActualLength] := Str[i];
    end;
  SetLength(Result, ActualLength);
end;

Back in 2011 I added a comment that for more than a decade would redirect to the most current documentation on the IsLetter method:

+1 for using IsLetter which checks the Unicode definition for being a letter or not [Wayback] docwiki.embarcadero.com/VCL/en/Character.TCharacter.IsLetter

Back then, Delphi X2 was current, so it would redirect

1. from [Wayback] http://docwiki.embarcadero.com/VCL/en/Character.TCharacter.IsLetter
2. to [Wayback] http://docwiki.embarcadero.com/VCL/XE2/en/Character.TCharacter.IsLetter
3. then to [Wayback] http://docwiki.embarcadero.com/VCL/XE2/en/Character.TCharacter.IsLetter
4. ending at [Wayback] http://docwiki.embarcadero.com/Libraries/XE2/en/System.Character.TCharacter.IsLetter

After a long outage in 2022 (see The Delphi documentation site docwiki.embarcadero.com has been down/up oscillating for 4 days is now down for almost a day.) only the Alexandria help was restored.

This killed the above redirect.

Luckily [Wayback/Archive] George Birbilis noticed that and commented this:

@JeroenWiertPluimers the correct link now is: docwiki.embarcadero.com/Libraries/Alexandria/en/…

In order to refer to the most recent Delphi version, now you have to use [Wayback] http://docwiki.embarcadero.com/Libraries/en/System.Character.TCharacter.IsLetter.

This redirects:

1. via [Wayback] http://docwiki.embarcadero.com/Libraries/Alexandria/en/System.Character.TCharacter.IsLetter to
2. to [Wayback] https://docwiki.embarcadero.com/Libraries/Alexandria/en/System.Character.TCharacter.IsLetter

The above breaks the help integration from older Delphi products which is bad. It is also bad because it makes it harder to port legacy Delphi code to more modern Delphi versions.

Hopefully the above gives you a bit insight how the docwiki help system was designed and what is left of that design.

–jeroen