c3-31 case13简单算术计算器

import java.util.Scanner;
public class Case13 {
    public static void main(String [] args){
        Scanner in = new Scanner(System.in);
        //接受第一个操作数
        double a = in.nextDouble();
        //接受操作符
        String operator = in.next();
        //接受第二个操作数
        double b = in.nextDouble();
        double result = 0;
        switch(operator){
            case "+":
                result = a + b;
                break;
            case "-":
                result = a - b;
                break;
            case "*":
                result = a * b;
                break;
            case "%":
                result = a%b;
                break;
            case "/":
                result = a/b;
                break;
            default:
                result = Double.NaN;
        }
        System.out.printf("%.2f%s%.2f = %.2fn",a,operator,b,result);
    }
}