while for do while 循环区别

import java.util.Scanner;
public class Demo2 {
    public static void main(String[] args) {
        先执行，在自增   如果循环条件不满足，不执行，直接跳过.
            int i = 0;
            while (i<=10){
                System.out.println("好好学习，天天向上");
                i++;
            }
        System.out.println("--------");

          先执行，在自增
        for (int j = 0; j <=10 ; j++) {
            System.out.println("good good study day day up");
           }
        System.out.println("--------");

             先执行，再判断,  至少执行一次
        int score = 60;
        do {
            //循环操作，循环体
            System.out.println("准备开始-------");
            System.out.println("考完了，我的得分是" + score++);
        }while (score<70);
        System.out.println("--------");

        System.out.println("请输入批阅成绩");
        Scanner sc = new Scanner(System.in);
        int  a = sc.nextInt();
        do {
            System.out.println("考试中--------上机编程");
            System.out.println("批阅成绩，你的成绩是：" + a++);

        }while (a < 70);
        System.out.println("成绩合格");
        System.out.println("--------");


          循环录入学生成绩，有错误停止录入
            int he = 0;
     System.out.println("请输入考生姓名");
            Scanner w =new Scanner(System.in);
            String name =w.next();

             for (int q = 1; q < 6; q++) {
                  System.out.println("请输入五门功课中第"+q+"门功课的成绩");
                 int cj =w.nextInt();

            he += cj;
            if (cj < 0 ){
                  break;
   }
          if (cj >= 0 ){
                System.out.println("五门功课的平均值为" + he/5);
            }else {
                System.out.println("数值录入错误");
            }
             }


          for 循环 计算10 以内相加大于20的数

             int sum = 0;
        for (int i = 1; i < 11; i++) {
             sum += i;
            System.out.println(sum);
            if (sum > 20){
                System.out.println(i);
                break;
            }
           for 循环  计算100以内偶数和
        }
        int num = 0;
        for(int j = 1; j <=100 ; j++) {
            if (j % 2 ==0){
                num+=j;
                System.out.println(num);
            }
        }
    while  计算100以内偶数和
                int i = 2;
                int num =0;
            while (i <= 100){
                num +=i;
                 i+=2;
                      System.out.println(num);
         }

   do while  计算100以内偶数和
                int i = 0;
                int sum =0;
                do {
                    sum +=i;
                    i +=2;
                    System.out.println(sum);
                }while (i <=100);
        ATM  取款
                Scanner w =new Scanner(System.in);
              System.out.println("请输入密码");
                String pwd =w.next();

        for (int i = 0; i <=3 ; i++) {
           if (pwd.equals("111111")){
                System.out.println("密码正确");
                break;
            }else {
                System.out.println("登陆失败");
                break;
            }
        }
            Scanner q =new Scanner(System.in);
            System.out.println("请输入取款金额");
            int money = q.nextInt();
            if (money%100==0){
                System.out.println("取款成功");
            }else {
                System.out.println("输入错误");
            }
            System.out.println("您的余额还有10000RMB");

           加法 算法
        System.out.println("请输入一个数");
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();

        int a = 0;
        int b = num;

        for (int i = 1; i <= num; i++) {
            int c = a++;
            int d = b--;
            System.out.println(c + "+" + d + "=" + num);


        }
    班级80分学生占比
        Scanner w = new Scanner(System.in);
        System.out.println("请输入班级总人数");
        int p = w.nextInt();
        int num =0;
        for (int i = 1; i <=p ; i++) {
            Scanner q =new Scanner(System.in);
            System.out.println("请输入第"+i+"个同学的成绩");
            int score =q.nextInt();
            if (score<80){
                continue;
            }
            num++;
    }
                 int bi = num/p*100;
                  System.out.println("80分以上的学生人数为"+num);
                 System.out.println("80分以上的同学所占的比例为"+bi+"%");



  10以内偶数和
        int num = 0;
        for(int j = 1; j <=10 ; j++) {
            if (j % 2 ==0){
                num+=j;
                System.out.println(num);
            }
        }


        }

    }