$b ++ if ( $_ eq "b" ) foreach @a ;
[download]

Any simple statement may optionally be followed by a SINGLE modifier, just before the terminating semicolon (or block ending).

This will work:

( $_ eq "b" ) and $b ++ foreach @a ;
[download]

foreach(@a) {
    $b ++ if ( $_ eq "b" );
}
[download]

p.s. I think it's not good style to detach the ++ operator from the lvalue it's working on. So, use $b++ instead of $b ++.

And in the

statement if condition;
[download]

do you mean there is a difference between $b++ and $b ++ ?

Apparently, there isn't. But I had to test it.

I just have a very hard time reading and understanding it — while it's just such a small thing. Bring on the huge expressions!

Your whitespace isn't improving readability — on the contrary.

You should remember that there _is_ a difference betwixt ++$b and $b++, however. ++$b doesn't have the nuisance of making a copy of its original value to return before incrementing, and therefore it's slightly less efficient if, as in this case, you don't need to know what that value was.

#!/usr/bin/perl
use strict ;
use warnings ;

my @foo = qw( a b c b d b e b f );

my $bar = grep { $_ eq 'b' } @foo;

print "$bar\n";
[download]

strict/warnings will clobber my $b because $a and $b are special variables. Change the name.

Dead wrong, that first guess. Two modifiers, one statement. Rewrite as,

$_ eq "b" and $b++ foreach @a ;
[download]

for (@a) {
    $b++ if $_ eq "b";
}
[download]

You can fill the array in one step using qw, and you can count all 'b' in this array in one step using grep:

my @ar  = qw /a b b a/;
my $cnt = 0 ;

$cnt    = grep /b/, @ar;
[download]