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
原文地址:https://www.cnblogs.com/quxiangjia/p/11987065.html