while ( ... ) {
    unless ( some-condition ) {
        next
    }
    some-code
}

##</code><code>##

while ( ... ) {
    if ( some-condition ) {
        some-code
    }
}

##</code><code>##

while ( <DATAFILE> ) {
    chomp;
    unless ( m{^ (\d\.\d{5}) \s*,\s* (\d\d:\d\d:\d\d) \s* (.*) $ }x ) {
        next
    }

    my ( $quote, $time, $comment ) = ( $1, $2, $3 ); # captures
    my ( $hours, $minutes, $seconds ) = split /:/, $time;

    #do something with $quote, $hours, $minutes, $seconds & $comment
}