<?php 
function factorial ($n) { 
 if ( ($n == 0) || ($n == 1) ) 
    return 1; 
   else 
    return $n*factorial($n-1); 
 } 
echo  factorial(4);
?>

<?php
function randInt($low,$high) { 
     srand ( date("s") ); 
     $range = $high - $low; 
     $num = (rand() % $range) + $low; 
     return $num; 
}
function binSearch($key,$array,$left,$right)
{
     $mid = ceil( ($left + $right) / 2 );
     if ($left > $right)
          return -1;
     if ($array[$mid] == $key)
         return $mid;
else if ($key < $array[$mid])
         return binSearch($key,$array,$left,$mid-1);  // recursive call
else
        return binSearch($key,$array,$mid+1,$right); // recursive call
}
$num=100;
$key = randInt(0,$num);
for($i=0; $i < $num; $i++) {
     $sorted_array[$i] = $i+1;
}
echo binSearch(13,$sorted_array,0,$num); 
?>

<?php
function randomToken($len) { 
   srand( date("s") ); 
   $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; 
   $chars.= "1234567890!@#$%^&*()"; 
   $ret_str = ""; 
   $num = strlen($chars); 
   for($i=0; $i < $len; $i++) { 
     $ret_str.= $chars[rand()%$num]; 
   } 
   return $ret_str; 
}
echo randomToken(13)," ";
?>