20の階乗

Main.java

package longCover;

public class Main{

	public static void main(String[] args){
		try{
			longTest(20);
		}catch(Exception e){
			e.printStackTrace();
		}
		try{
			doubleTest(20);
		}catch(Exception e){
			e.printStackTrace();
		}
		/*/
		 * long test
		 * 1*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16*17*18*19*20=2432902008176640000
		 * long max-l=6790470028678135807
		 * double test
		 * 1.0*2*3*4*5*6*7*8*9*10*11*12*13*14*15*16*17*18*19*20=2.43290200817664E18
		 * double max-d=1.7976931348623157E308
		 */
	}

	public static void longTest(int cnt){
		long l = 1;
		System.out.println("long test");
		System.out.print(l);
		for(int i = 2;i<=cnt;i++){
			System.out.print('*');
			System.out.print(i);
			l = l*i;
		}
		System.out.print('=');
		System.out.println(l);
		System.out.print("long max-l=");
		System.out.println(Long.MAX_VALUE-l);
	}

	public static void doubleTest(int cnt){
		double d = 1;
		System.out.println("double test");
		System.out.print(d);
		for(int i = 2;i<=cnt;i++){
			System.out.print('*');
			System.out.print(i);
			d = d*i;
		}
		System.out.print('=');
		System.out.println(d);
		System.out.print("double max-d=");
		System.out.println(Double.MAX_VALUE-d);
	}
}

doubleよくわかんない()