My Timezone is GMT +1, Daylight

Unix Timestamp is Seconds since 1.1.1970

I want to calculate in Days!

One Day has: 60*60*24 Seconds = 86400 Seconds

So for calculating in Days I divide the Unix TimeStamp throu 86400 and cut the rest

But while programming I found a strange behaviour:

  $time = gmmktime(1,0,0,4, 30, 1999);  // 1 hour if Daylight else 0 hours to get a Unix Timestamp 
                                                           // without a Rest if divide throu 86400 in Days 
  $time2 = mktime(2,0,0,4, 30, 1999);  // 1 hour if Daylight else 0 hours + 1 hour GMT +1 for my Timezone
                                                         // to get a Unix Timestamp 
                                                         // without a Rest if divide throu 86400 in Days 
  echo $time."-".$time2."\n";
  echo ($time/86400)."-".($time2/86400)."-".date("YmdHis",$time)."-".date("YmdHis",$time2)."\n";


My Probem is:

1. Why is the Conversion doing such?
2. Not every Country has Daylight, so what can i do if the script should run on a site without daylight
   May I thest every time my scipt for such hidden bugs?

bye Peter.