How to creat calculator by using C.programing

#include <stdio.h>
int main(){

    float num1;
    float num2;
    char op;
    float result;



    printf("Enter the first number");
    scanf("%f",&num1);

    printf("Enter the operation");
    scanf(" %c",&op);



    printf("Enter the secound number");
    scanf("%f",&num2);

    switch(op)
    {
    case'+':
        result= num1 + num2;
        printf("%f",result);
        break;
        case'-':
        result= num1 - num2;
        printf("%f",result);
        break;
        case'*':
        result= num1 * num2;
        printf("%f",result);
        break;
        case'/':
        result= num1 / num2;
        printf("%f",result);
        break;
        default :
            printf("This operation is error!");
    }

    getchar();
}