Calculator

char sign = ' ';
        double a=0, b=0;
        Scanner in = new Scanner(System.in);
        System.out.println("Please enter the number:");
        a = in.nextDouble();
        while(sign != 's')
        {
            System.out.println("Please enter the sign");
            sign = in.next().charAt(0);
            if (sign == '+')
            {
                System.out.println("Please enter the next number:");
                b = in.nextDouble();
                a+=b;
            }
            if (sign == '-')
            {
                System.out.println("Please enter the next number:");
                b = in.nextDouble();
                a-=b;
            }
            if (sign == '*')
            {
                System.out.println("Please enter the next number:");
                b = in.nextDouble();
                a*=b;
            }
            if (sign == '/')
            {
                System.out.println("Please enter the next number:");
                b = in.nextDouble();
                a/=b;
            }
            if (sign == '^')
            {
                System.out.println("Please enter the next number:");
                b = in.nextDouble();
                a = Math.pow(a, b);
            }
            if (sign == 'v')
            {
                a=Math.sqrt(a);
            }

        }
        System.out.print(a);