What are the differences and similarities between pointers and references?

1. The similarities between references and pointers

1. Both pointers and references can optimize parameter passing efficiency;

2. Both are concepts of address; the

pointer points to a piece of memory, and its content is the address of the pointed memory; the reference is the alias of a certain piece of memory.

2. The difference between references and pointers

1. Pointers occupy memory space, while references do not occupy memory space;

2. Pointers can be Null, but the reference cannot be null;

3. The pointer does not need to be initialized, but the reference must be initialized;

4. The pointer can have multiple levels, but the reference can only be one level;

5. The value of the pointer can be changed after initialization, that is, it points to other storage units, but the reference will not change after initialization.

6. The pointer is A variable, whereas a reference is just a reference.

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