I find this to be really interesting advise but I wonder when this is right and when this would be wrong. Especially in C, where a lot of data is passed throug

I find this to be really interesting advise but I wonder when this is right and when this would be wrong. Especially in C, where a lot of data is passed through pointers, you'd want to make sure the data you are given isn't pointing to nothing and can't always rely on the callee doing it for you.