simple calculator(using c)

#include <stdio.h>
#include<stdlib.h>
int main()
{
    char ch,x;
    double a,b;
    while(1)
    {
        printf("enter any operation(+,-,*,/),if you want exit press x::\t");
        scanf(" %c",&ch);
        if(ch=='x')
        {
            printf("you are exited");
            exit(0);
        }
        printf("enter first operand::\t");
        scanf("%lf",&a);
        printf("enter second operand::\t");
        scanf("%lf",&b);
        switch(ch)
        {
            //AXxdiition::
            case '+':
                printf("%.1lf + %.1lf = %.1lf\n",a,b,a+b);
                break;
            //Substraction::
            case '-':
                printf("%.1lf - %.1lf = %.1lf\n",a,b,a-b);
                break;
            //Multiplication::
            case '*':
                printf("%.1lf * %.1lf = %.1lf\n",a,b,a*b);
                break;
            //Division::
            case '/':
                if(b!=0)
                {
                printf("%.1lf / %.1lf = %.1lf\n",a,b,a/b);
                 
                }
                else
                {
                    printf("Error! Division by zero is not allowed.\n");
                }
                break;
        default:
        {
            printf("Error!,please enter the valid input!!");
        }
        }
        printf("\n");
    }
}