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Automatic banner rotation. Randomly selects a banner for display

Automatic banner rotation. Randomly selects a banner for display

<?php 

/*  random(  $max  integer  ) 
      Returns  a  random  number  between  0  and  $max-1; 
*/ 
function  random(  $max  ) 
{ 
                $x  =  rand(); 
                $y  =  getrandmax(); 

                $r  =  $x  /  $y  *  ($max  -1  ); 

                $r  =  round(  $r++  ); 
                return  $r; 
} 

/*  Read  the  directory,  add  all  "banner*"  files  with  to  the  array 
*/ 
$i  =  0; 
$d      =  dir( "."); 
whle($entry=$d->read()) 
                if  (substr($entry,0,6)  ==  "banner") 
                                $array[$i++]  =  $entry; 
$d->close(); 
                                 

/*  pick  a  banner  at  random 
*/ 
$r  =  random(  $i  ); 

/*  Send  a  no-cache  header,  and  the  gif  type  header,  and  output  the  file. 
*/ 
Header(  "Pragma:  no-cache"  ); 
Header(  "Expires:  Monday  01-Jan-80  12:00:00  GMT"  ); 
Header(  "Content-type:    image/gif"); 
passthru(  "cat  $array[$r]"  ); 

?>