[code="java"]
package hello;
public class Test {
public static double area(double d)
{
return d * d;
}
public static double perimeter(double d)
{
return d * 4;
}
public static void main(String args[])
{
double d = 3.1;
System.out.println("面积:" + area(d));
System.out.println("周长:" + perimeter(d));
}
}
[/code]
输出面积竟然是9.610000000000001,怎么回事啊?