Re: Perl Idioms Explained - @ary = $str =~ m/(stuff)/g

[bart]

$num_matches_stuff = $str =~ m/(stuff)/g;
@all_the_matches   = $str =~ m/(stuff)/g;

In scalar context we get the count of the matches, in array context we get the matches.

No, the former just is not right. You haven't actually tried it, have you?

$str = "stuff stuff stuff";
$num_matches_stuff = $str =~ m/(stuff)/g;
print $num_matches_stuff;

Result:

1

The /g modifier in scalar context is very special. It is intended to be used in a loop, something like this:

$str = "stuff stuff stuff";
while($str =~ m/(stuff)/g) {
    print "Got one!\n";
}

Result:

Got one!
Got one!
Got one!

So in scalar context, it will match at most once at a time — next time around, it'll continue where it left off last time.

Therefore, the returned valued of //g when used in scalar context is either 0, or 1.

[tachyon]

Hmm it is of course as you say. I must have got myself confused with the behaviour of s///.

$data = 'stuff stuff stuff';
$num = $data =~ s/(stuff)//g;
print $num, $/;
__DATA__
3

You can force it to do as I said by cheating thusly....

$num = () = 'stuff stuff stuff' =~ m/(stuff)/g;
print $num;
__DATA__
3

cheers

tachyon

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