I recieved some comments about this class and some members told me they cannot 
see the chart in their browsers. Some browsers cannot get the header of the page 
automatically so I think it is better to add the following line to piechart.php 
second and after <?php tag.
header ("Content-type: image/jpeg");
I should thank people who commented me on this class specially    
Arn&oacute;r Hei&eth;ar from Ireland for this correction file.