Java练习题

编写程序计算1！+2！+3！+…+n！，并输出计算结果。

 

import java.util.Scanner;

public class Factorial {
    public static void main(String[] args) {
        long t = 1;
        long sum = 0;
        Scanner sc = new Scanner(System.in);
        if(sc.hasNextInt()){        ////判断输入值是否为int类型
            int n = sc.nextInt();
            for (int i = 1; i <= n; i++) {
                for (int j = 1; j <= i; j++) {      //计算n的阶乘
                    t *= j;
                }
                sum += t;
                t = 1;
            }
            System.out.println("小于整数:"+n+"的所有正整数阶乘之和是："+sum);
        }
        else
            System.out.println("输入错误！");
    }
}