Ohh my bad. I corrected G with \G but still no chnage ... prints nothing. Still not sure what difference it was supposed to make. 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $x = '1 2 3kg 4 5 6 7 8 9 10Kg 11 12 13 kg 14 15';
 print qq{string \$x: '$x'};
 ;;
 printf qq{captured '$1'  } while $x =~ /\G(\d+)\s*kg\s*/ig;
 print '----------';
"
string $x: '1 2 3kg 4 5 6 7 8 9 10Kg 11 12 13 kg 14 15'
----------

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The  \G anchor matches at the point (the exact character offset in the string) at which matching stopped in the last  /g global match iteration. But on the first  /g iteration, where is that point? On the first  /g iteration,  \G matches the same as  \A (the \Absolute-start-of-string anchor).

So what  /\G(\d+)\s*kg\s*/ig says is:

  1. \G From the string offset at which the previous match stopped (or from the start of the string if it's the first match);
  2. (\d+) Match and capture one or more decimal digits;
  3. \s* Then match zero or more whitespace characters;
  4. kg Then match the literal characters  'kg' case-insensitively (due to the  /i flag);
  5. \s* Then match zero or more whitespace characters (this can't fail);
  6. And this match iteration is finished.

But your  '1 2 3kg 4 5 6 7 8 9 10Kg 11 12 13 kg 14 15' string begins with some digits, some whitespace, and then some more digits, not the required  'kg' literals: the match immediately fails. There is a  '3kg' subsequence further on that could satisfy part of the overall match, but matching has already failed due to the  \G assertion.

Give a man a fish:  <%-{-{-{-<

In reply to Re^5: Regular expression by AnomalousMonk
in thread Regular expression by pravakta

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