实验三：分别用for、while和do-while循环语句以及递归方法计算n！，并输出算式

 1 package For;
 2 
 3 import java.util.Scanner;
 4 public class FORXH {
 5 
 6     public static void main(String[] args) {
 7         int n,i,sum=1;
 8         System.out.print("请输入n：");
 9         Scanner in=new Scanner(System.in);
10         n=in.nextInt();
11         for(i=1;i<=n;i++)
12         {sum=sum*i;}
13         System.out.println(sum);
14 
15     }
16 
17 }

 1 package While;
 2 
 3 import java.util.Scanner;
 4 
 5 public class WHLIE {
 6 
 7     public static void main(String[] args) {
 8     
 9         int n,i=1,sum=1;
10         System.out.print("请输入n：");
11         Scanner in=new Scanner(System.in);
12         n=in.nextInt();
13         while(i<+n)
14         {
15             sum=sum*i;
16             i++;
17         }
18         System.out.println(sum);
19     }
20 
21 }

 1 package Dowhile;
 2 
 3 import java.util.Scanner;
 4 
 5 public class DOWHILE {
 6 
 7     public static void main(String[] args) {
 8         // TODO Auto-generated method stub
 9 
10         int n,i=1,sum=1;
11         System.out.print("请输入n：");
12         Scanner in=new Scanner(System.in);
13         n=in.nextInt();
14         do {
15             sum=sum*i;
16             i++;
17         }
18         while(i<=n);
19             System.out.println(sum);
20     }
21 
22 }

 1 package Digui;
 2 
 3 import java.util.Scanner;
 4 
 5 public class DIGUI {
 6 
 7     public static void main(String[] args) {
 8         int n;
 9         System.out.print("请输入n：");
10         Scanner in=new Scanner(System.in);
11         n=in.nextInt();
12         fun(n);
13         System.out.println(fun(n));
14     }
15 public static int fun(int n) {
16     if(n==1||n==0) return 1;
17     else return n*fun(n-1); 
18     
19 }
20 }