I thought the documentation said that:

... which prints 
    Got a TGA stop codon at position 18
    Got a TGA stop codon at position 23

[download]

Position 18 is good, but position 23 is bogus. What happened?

The answer is that our regexp works well until we get past the last real match. Then the regexp will fail to match a synchronized TGA and start stepping ahead one character position at a time, not what we want. The solution is to use \G to anchor the match to the codon alignment: ...

If there is no match at all, I would assume that we are always past the last real match.

In reply to Re^2: Understanding a portion of perlretut by Corion
in thread Understanding a portion on the Perlretut by BlueStarry

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