Using Regex to replace string in Delphi

Question

From Official documentation of RegularExpressions, the output should be NUMabcabc. But it is not. I wonder what is wrong ?

program Project128;

{$APPTYPE CONSOLE}

uses RegularExpressions;

var Regex: TRegEx;
begin
  Regex := TRegEx.Create('{[0-9]}{[a-c]*}');
  WriteLn(Regex.Replace('3abcabc', 'NUM\1'));
  ReadLn;
end.

Answer 1

You've got the wrong docs. The docs you reference are for the regex flavour used by IDE search and replace. That flavour of regex is just used by the IDE. The flavour used by the RegularExpressions unit is PCRE, which is quite different and is documented here.