The difference between C + + references and pointers

I. Definitions of references and pointers

Reference: It takes an alias to another variable and does not allocate space again (which can lead to optimization of the program)

Pointer: It is an entity that needs to allocate space

references must be initialized at the time of definition, and space cannot be changed .

The pointer does not have to be initialized at the time it is defined, and the space it points to is variable . (Note: The referenced value cannot be null)----------> can bring program security

A reference to access a variable is directly accessible, while a pointer to access a variable is an indirect access

Second, C + + initialization function 6 default functions

1. Constructors

2. Destructors

3. Copy constructors (when function arguments are objects)-------> shallow copy deep copy

Text T1;

Text T2 (T1)

Text t2 = t1;

4. Assignment function-----------> Shallow Assignment depth value

Text T1;

Text T2;

t2 = T1;

5.Text A;

Text *b = &a;

text* operator& () {return this};

　　

6.const Text A (constant object);

Const Text *B = &a;

Const text* operator () {return this};

Third, deep copy, shallow copy

Execution procedure: Call the constructor once, customize the copy constructor once, and two times the destructor. A pointer member of two objects refers to a different memory.

A shallow copy is just a copy of the pointer, and the two pointers point to the same memory space

A deep copy not only copies the pointer, but also copies the contents of the pointer, which is a pointer to two different addresses.

Student::student () {      name = new char ();      cout << "Student" << Endl;} Student::~student () {         cout << "~student" << (int) name << Endl;         Delete name;         name = NULL;} Student::student (const Student &s) {         name = new char (a);         memcpy (name, S.name, strlen (s.name));         cout << "Copy Student" << Endl;}

The difference between C + + references and pointers