calculator in c

#include<stdio.h>
#include<stdlib.h>
int main(){
double num1, num2, sum;
char op;

printf("Enter expression: ");
scanf("%lf %c %lf", &num1, &op, &num2);
if(op == '+'){
    sum = num1 + num2;
}else if(op == '-'){
    sum = num1 - num2;
}else if(op == '*'){
    sum = num1 * num2;
}else if(op == '/'){
    sum = num1 / num2;
}else{
    fprintf(stderr, "Invalid input!\n");
    return EXIT_FAILURE;
}
printf("Result = %.2lf\n",sum);

    return EXIT_SUCCESS;
}