What, nobody remembers grep in grep BLOCK LIST usage?!

@l = qw( a b c );

#  '@m' just as well be '()' unless used later, but then I personally
#  would be doing C</a/ and $_ = 'z' for @l;>.
@m =  grep { /a/ and $_ = 'z' } @l;

print @l;
[download]

And a different take on reply from Sidhekin ...

/a/ and $_ = 'z' for @l;
[download]

~Nov 26 2006, 7p US-EDT: Changed '@p' to '@l'.