import java.util.Scanner;
public class Test {

    public static void main(String[] args) {

        count();

    }

    public static void count() {

        Scanner input1 = new Scanner(System.in);

        System.out.println("输入一个数");

        double a = input1.nextDouble();

        while (true) {

            Scanner input3 = new Scanner(System.in);

            System.out.println("提示：请输入您的操作");

            System.out.println("+");

            System.out.println("-");

            System.out.println("*");

            System.out.println("/");

            System.out.println("F:退出");

            String str = input3.nextLine();

            char chr = str.toCharArray()[0];

            switch (chr) {

            case '+':

                a = add(a);

            System.out.println("当前结果为："+a);

                break;

            case '-':

                a = subtrace(a);

                System.out.println("当前结果为："+a);

                break;

            case '*':

                a = ride(a);

                System.out.println("当前结果为："+a);

                break;

            case '/':

                a = except(a);

                System.out.println("当前结果为："+a);

                break;

            case 'F':

                System.out.println("结果:" + a);

                System.exit(-1);

            default:

                System.out.println("操作错误！");

                break;

            }

        }

    }

    public static double add(double a) {

        Scanner input2 = new Scanner(System.in);

        System.out.println("输入一个数");

        double b = input2.nextDouble();

        return (a + b);

    }

    public static double subtrace(double a) {

        Scanner input2 = new Scanner(System.in);

        System.out.println("输入一个数");

        double b = input2.nextDouble();

        return (a - b);

    }

    public static double ride(double a) {

        Scanner input2 = new Scanner(System.in);

        System.out.println("输入一个数");

        double b = input2.nextDouble();

        return a * b;

    }

    public static double except(double a) {

        Scanner input2 = new Scanner(System.in);

        System.out.println("输入一个数");

        double b = input2.nextDouble();

        return a / b;

    }

}