Question

If I have the following for example:

int *x;
x = func(a);

For the statement: x = func(a);, do we say that we are returning an address to x? Or, how exactly do we read it?

EDIT: Is it eligible to say that we are returning a pointer to x? If so, can you explain how this is done exactly? I mean, how are we returning a pointer?

Answer 1

x is a pointer, specifically to an int. So it should be obvious that there are two memory locations used. One for the pointer and one for the memory it’s pointing to (assuming the pointer is not null).

The pointer itself holds a memory address, specifically the location of the memory it’s pointing to. Something like 0xa456e4fa.

Yes, func() is returning a pointer. The prototype of func would look like the following..

int * func(someObj a); //I don't know the datatype of your parameter,
                       //so I'm just making something up.

Notice the return type is a pointer to an int. From this and what I said previously, it should be obvious what this will return. Something of the form 0xyyyyyy, or a memory address/pointer. That memory address goes into your x pointer.

Remember that the pointer itself is not holding the data that it’s pointing to, it is only the address. There’s really no reason you CAN’T return a pointer. However, you do need to be careful in WHAT you return. You do not want to return the address of a local variable because that variable will go out of scope once the function has completed its execution. You’ll then be returning the address of something invalid. Returning the VALUE of a local pointer however, is fine because the value you returned (the address) will be preserved as will the memory it’s pointing to.

I also just realized I wrote you a book. Damn, I sure do ramble when I’m tired.