perl -le "print eval(print 1+1)"

##</code><code>##

2      <-- printed within the eval()
1      <-- printed outside the eval()

##</code><code>##

perl -le "$i=5;print $i,eval('$i++;print $i;');print $i"

##</code><code>##

6      <-- printed outside the eval(), but AFTER it has run so $i has been incremented
61      <-- 6 printed within the eval(), 1 printed outside
6      <-- printed in the next statement outside the eval()