JAVA基础学习（3）之循环

3循环

3.1循环

3.1.1循环
- 一直要做的行为进行循环

3.1.2数数字

while(){}判断是否进行
数数字：number/10

 1 //数数字
Scanner in = new Scanner(System.in);
 2         System.out.println("请输入一个数！");
 3         int number = in.nextInt();
 4         int count = 0;
 5         while (number > 0)
 6         {
 7             number = number / 10;
 8             count++;
 9             System.out.println("number=" + number + " count=" + count);
10         }
11         System.out.println("该数有" + count + "位！");

3.1.3while循环

测试数据

个位数
10
0
负数

 1 Scanner in = new Scanner(System.in);//解决0的数数字
 2         System.out.println("请输入一个数！");
 3         int number = in.nextInt();
 4         int count = 0;
 5         do
 6         {
 7             number = number / 10;
 8             count++;
 9             System.out.println("number:" + number + " count:" + count);
10         } while (number > 0);
11         System.out.println("该数有" + count + "位");

3.1.4do-while循环

while();分号不能忘记

//计数循环
Scanner in = new Scanner(System.in);
        int count = 100;
        do
        {
            System.out.println(count);
            count = count - 1;
        } while (count > 0);
        System.out.println(count);
        System.out.println("发射!");

3.2循环的例子

计数循环
- 如果要模拟运行一个很大次数的循环，可以模拟较少的循环次数，然后作出判断。

算平均数

 1 Scanner in = new Scanner(System.in);//计算平均数
 2         int number;
 3         int sum = 0;
 4         int count = 0;
 5         while ((number = in.nextInt()) != -1)
 6         {
 7             sum = sum + number;
 8             count++;
 9         }
10         if (count > 0)
11         {
12             System.out.println("平均数为：" + (double) sum / count);
13 
14         }

猜数

 1 Scanner in = new Scanner(System.in);//猜数游戏
 2         int number = (int) (Math.random() * 100 + 1);// [0,1)-->[0,100)-->[1,100]
 3         int a;
 4         int count = 0;
 5         while ((a = in.nextInt()) != number)
 6         {
 7             if (a > number)
 8             {
 9                 System.out.println("大了");
10             } else if (a < number)
11             {
12                 System.out.println("小了");
13             }
14             count++;
15         }
16         System.out.println("恭喜你猜对了,你猜了" + count + "次！");

整数分解

 1 Scanner in = new Scanner(System.in);//整数分解
 2         int number;
 3         number = in.nextInt();
 4         int result = 0;
 5         do
 6         {
 7             int digit = number % 10;
 8             result = result * 10 + digit;
 9             System.out.print(digit);
10             number = number / 10;
11         } while (number > 0);
12         System.out.println();
13         System.out.println(result);

n%10->得到个位
n/10->去掉一位

posted on 2019-12-05 09:16 生长的力量阅读(188) 评论(0) 编辑收藏举报