print "number of cols= $#{s1[$i]}\n";
if ($j=0;$j<$#{s1[$i]};$j++)

##</code><code>##

# dont put @array in string or it prints the elements
print "number of cols=".@{s1[$i]}."\n";
for(my $j=0;$j<scalar @{s1[$i]};$j++) # explicit scalar