import java.util.Scanner;
public class Calculation_Demo_01 {
    public static void main(String[] args) {
        while (true) {
            Scanner scanner = new Scanner(System.in);
            System.out.println("请输入有效数字a");
            double a = scanner.nextDouble();
            System.out.println("请输入有效数字计算符");
            String c = scanner.next();
            System.out.println("请输入有效数字b");
            double b = scanner.nextDouble();
            System.out.println(calculation(a, c, b));
        }
    }
    public static double calculation (double a,String c,double b) {
        double d = 0;
        switch (c) {
            case "+" :
                d = a + b;
                break;
            case "-" :
                d = a -b;
                break;
            case "*" :
                d = a * b;
                break;
            case "/" :
                d = a / b;
                break;
            default:
                System.out.println("非法的运算符");
        }
        return d;
    }
}