do-while、随机输入n计算1+2+3+...+n的值

package ture_f;

import java.util.Scanner;

public class do_while_yuju {
    public static void main(String[] args) {
        int n;
        int i=1;
        Scanner sc=new Scanner(System.in);
        System.out.println("请输入n=:");
        n= sc.nextInt();
        int sum=n;
        do {
            sum+=i;
            i++;
        }while (i<=n);
        System.out.println("1+...+n="+sum);
    }
}

运行结果