Question:
I’m trying to make a calculator program using switch statements for +,-,* and /. I know how to handle and divide by zero error. I also have to use the cin.good() function to check whether the inputted numbers or the requested operation is good. Whenever I try to use the cin.good() function, I get an error saying that ‘good’ is an undefined variable. What can I do, and how should I use it correctly?

Answer:
Unless you’re using a very outdated compile or you omitted the parentheses after the function’s name, your code should compile. Make sure that you’re using the appropriate user-declaration or qulaified name to ensure that the compiler recognizes the object cin. Here’s an exmaple:

#include int main(){ bool b = std::cin.good();}

If your compiler fails to compile it, you should probably upgrade it.