Size of @+

[merlyn]

OK, I've seen this go by (incorrectly) in the CB twice in a week, so I'm going to post a note on it so I can refer to it again and again.

After this code:

my @x = "abcdefgh" =~ /(.)(.)/g;

the size of @+ is three elements, since it records only the most recent complete regex match, with ending position info for $&, $1, $2 (3 elements total). The values are (8, 7, 8).

The size of @x is indeed eight elements: the cumulative total of how many different memories matched for all matches (four matches, two apiece).

There. Let's please have no more advice in the CB that the way to get the "number of matches" is to look at @+. Thank you.

-- Randal L. Schwartz, Perl hacker

[roho]

Just a quick side note. @+ does not interpolate inside double quotes. Printing it inside double quotes results in @+, not its contents. Printing it outside double quotes results in its contents. Feature or bug?

[Chmrr]

Bug. This is fixed between 5.6.1 and 5.8.0: Compare:

$ perl -e '"foo" =~ /(o)/; print @+,$/'
22
$ perl -e '"foo" =~ /(o)/; print "@+",$/'
@+
$ perl -v
This is perl, v5.6.1 built for i686-linux

..to:

$ perl -e '"foo" =~ /(o)/; print @+,$/'
22
$ perl -e '"foo" =~ /(o)/; print "@+",$/'
2 2
$ perl -v
This is perl, v5.8.0 built for i386-linux-thread-multi

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'

[tommyw]

Except, of course, read "The entire match" instead of $0.

Update:I'm blind, or merlyn's updated that. Would have sworn it said $0, not $&. Oh well. I'll go back to sleep now.

--
Tommy
Too stupid to live.
Too stubborn to die.

[blakem]

You aren't blind.... you can see the original by using my original node cache.

-Blake

[merlyn]

Yes, it was an update. Mind-slip.

-- Randal L. Schwartz, Perl hacker

[cluka]

This is one of the those cases where as a new perl programmer I jump into perlvar to figure out what these variables are.

If I understand the documentation correctly, @+ would be calculated as follows:

1: Entire regex matched the'gh' in 'abcdefgh'. End of match is 8. (This corresponds to $&).

2: First backreference matches 'g'. End of match is at position 7. ($1)

3: 2nd backreference matches 'h'. End of match is at position 8. ($2) Am I on track? Thanks