c++: pointer VS reference

http://stackoverflow.com/questions/57483/what-are-the-differences-between-a-pointer-variable-and-a-reference-variable-in

https://www.dgp.toronto.edu/~patrick/csc418/wi2004/notes/PointersVsRef.pdf

Summary from answers and links below:

1. A pointer can be re-assigned any number of times while a reference can not be re-seated after binding.
2. Pointers can point nowhere (NULL), whereas reference always refer to an object.
3. You can't take the address of a reference like you can with pointers.
4. There's no "reference arithmetics" (but you can take the address of an object pointed by a reference and do pointer arithmetics on it as in &obj + 5).

To clarify a misconception:

The C++ standard is very careful to avoid dictating how a compiler must implement references, but every C++ compiler implements references as pointers. That is, a declaration such as:

int &ri = i;

if it's not optimized away entirely, allocates the same amount of storage as a pointer, and places the address of i into that storage.

So, a pointer and a reference both occupy the same amount of memory.

As a general rule,

• Use references in function parameters and return types to define useful and self-documenting interfaces.
• Use pointers to implement algorithms and data structures.

Interesting read:

• My alltime favorite C++ FQA lite.
• References vs. Pointers.
• An Introduction to References.
• References and const.

================总结================

C++编译器使用指针来实现引用。

对于指针，需要使用 * 来 解引用(dereference)；对于引用，解引用是编译器自动完成的。（可以查看使用“引用的”汇编代码来确认。）