正Man's World

public class hw
//main
{
public static void
       main(String [] args)

 {
 int x,y,a,b;

 x=10;
 y=10;

 System.out.println("x++= " + x++ +":x= " +x);
 System.out.println("--y= " + --y +":y= " +y);
 a=17;
 b=3;
  System.out.println("r= " + a/b + ":r= " + (float)a/b + ":r= " + a/(float)b + " :r= " + (float)a/(float)b);

 final double PI=3.14159;
 double r;
 r=4.0;  //強制Double可以省略 因為r已經設為double了，反之若r為int 亦同
 System.out.println("當r=4.0");

 //強制資料型態為double時
 System.out.println("圓周長=" + 2*(double)r*(double)PI + "；面積=" + (double)r*(double)r*(double)PI );
 
//強制資料型態為int時
 System.out.println("圓周長=" + 2*(int)r*(int)PI + "；面積=" + (int)r*(int)r*(int)PI );
 System.out.println(" ");
 
r=100.0;
 System.out.println("當r=100.0");
  
//強制資料型態為double時
 System.out.println("圓周長=" + 2*(double)r*(double)PI + "；面積=" + (double)r*(double)r*(double)PI );
 
//強制資料型態為int時
 System.out.println("圓周長=" + 2*(int)r*(int)PI + "；面積=" + (int)r*(int)r*(int)PI );
 }
}