Differene between reference object and value object

Quote:

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Originally Posted by csonx_p

Oh, now you making interesting comment to me here ... So in some regard, one can refer an address variable a const pointer to some degree! The differences between

Code:

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Address& add;
const Address& myadd;

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you can change the members of add class (setAddress(x, y, z), etc), but with myadd, you cant?? But, also you can't change add to another Address object....

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That's right. (And of course, you can't change myadd to another address object either.) And since it's a reference, any changes made in this function are reflected back in the original wherever-we-came-from as well. (I think we're dealing with functions here, but I admit I've lost track.)

If we were using pointers, it would be Address * const add - that is, the pointer itself can not change, but the content can.

However, _I_ still think you should use a Address member, not a reference - there is no point in using a reference here - you still need an address, and the address itself is not a free-standing object that makes any sense. So storing the address in full inside the driver is a fine thing to do.

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Mats

Quote:

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Originally Posted by csonx_p

Code:

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Address& add;
const Address& myadd;

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you can change the members of add class (setAddress(x, y, z), etc), but with myadd, you cant?? But, also you can't change add to another Address object....

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Put in very simply terms... you can only call const functions on the myadd variable, because it's a const reference.
A const function is, simply put, a function that promises to never change the internal state of the class*.

And as some have mentioned, references cannot be reassigned.

Code:

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int a = 10;
int b = 20;
int& x = a;
x = 30;
x = b; // Oops, assigns 20 (the contents of b) to a.
x = 40; // Oops, assigns 40 to a, not b.

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*) It's actually possible to make an exception to what const functions MAY modify in a class, but let's ignore that for now.