2+2 illustrates some interesting behavior.

1. ++$_ && $_++ && print eval() + eval();
2. $_++; print eval() + eval() unless ( $_ + 1 == $_++ );
3. for (2..2){$_ = $_ + $_ and print;}
4. $a = 2; print "$a + $a = ", $$b + $$b; BEGIN{ $b = \$a }
5. my $num = 2; $num =~ s/(2)/$1 + $1/gxe; print $num;

mkmcconn