Factorial of a number in php

This is a small program which generates a factorial of a number in php.

function doFactorial ($x) { 
    if ($x <= 1) 
        return 1; 
    else 
        return ($x * doFactorial ($x-1)); 
} 

while($i<100)
{
 print $i." --> ".(doFactorial ($i)) . "
"; 
 $i++;
}
?>

Its a very basic program which generates a factorial of small numbers.