Yes. Grep.

my @a=('a' .. 'z');
print scalar grep {$_ eq "q"} @a;
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...this is actually equivalent to a foreach loop, so don't do it for big arrays. There is no quick way to do that - if you must, use hashes instead. The above (last line) is more-or-less equivalent to:

my @foo;
foreach (@a) {
  push @foo,$_ if ($_ eq "q");
}
print scalar @foo;
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HTH.

Originally posted as a Categorized Answer.