my $date;
my $lastdate = '';
my $logdata = '';
while ( <LOGFILE> ) {
   $date = extract_date( $_ );
   $logdata .= $stuff;
   if (length $lastdate and $lastdate ne $date) {
     print_report( $lastdate, $logdata );
     $logdata = '';
   }
   $lastdate = $date;
}
print_report( $lastdate, $logdata );

##</code><code>##

  ( $date, my $stuff ) = parse( $_ );
  $logdata .=  $stuff;
  # etc.

##</code><code>##

if ( $lastdate and $lastdate ne $date ) {

##</code><code>##

my $date;
my $lastdate = '';
my $logdata = '';
while ( <LOGFILE> ) {
   ( $date, my $stuff ) = parse( $_ );
   $logdata .= $stuff;
   if ( $lastdate and ( $lastdate ne $date or eof LOGFILES ) ) {
     print_report( $lastdate, $logdata );
     $logdata = '';
   }
   $lastdate = $date;
}