Checking for null before pointer usage

Question

Most people use pointers like this...

if ( p != NULL ) {
  DoWhateverWithP();
}

However, if the pointer is null for whatever reason, the functi

Answer 1

I prefer this style:

if (p == NULL) {
    // throw some exception here
}

DoWhateverWithP();

This means that whatever function this code lives in will fail quickly in the event that p is NULL. You are correct that if p is NULL there is no way that DoWhateverWithP can execute but using a null pointer or simply not executing the function are both unacceptable ways to handle the fack the p is NULL.

The important thing to remember is to exit early and fail fast - this kind of approach yields code that is easier to debug.