$ perl -e 'my $var = 5; my $res= $var--; print $res'
$ 5
$ perl
my $var = 5;
my $counter = 0;

for ( my $i = $counter; $var--; 1 ) {
    print ++$counter;
}
12345
$ perl -E 'my $var = 1; say "yes" if $var--'
yes
$ perl -E 'my $var = 0; say "yes" if $var--'
$