$block_comment = 0;
while ( <INPUT> ) {
    if    ( m{^//}  ) { next; }
    elsif ( m{^/\*} ) { $block_comment = 1; next; } # start block
    elsif ( m{^\*/} ) { $block_comment = 0; next; } # end block
    elsif ( $block_comment) { next; } # inside block
    else { ... do something with the line, that is no comment ... }
}