某工厂使用 一种圆柱形的铁桶来运输色拉油，但是关于该油桶的容量已经模糊，现在工人们测得油桶直径和高（由键盘输入），请设计一个圆柱形类CCylinder帮工人们计算一下油桶的容量和制造该油桶需要的铁皮面积。-A factory use the use of a cylindrical drum to transport salad oil, but about the oil drum capacity has fuzzy, now the workers measure oil drum diameter and high (by keyboard input), please design a cylindrical class CCylinder people to calculate the oil drum capacity and make the oil drum need sheet area.