C + + operator overloading and some basic concepts

C++primer Fourth Edition 435

1. Assignment (=), subscript ([]), Call (()), member Access Arrow (-) operator must be defined as member, when defined as non-member, compiler error

2. Like a value assignment. A conforming assignment operator should normally be defined as a member of a class, but no compilation error occurs when a compound assignment operator is defined as a non-member

3. Some other operators, such as self-increment, self-subtract, and dereference, that change the state of an object or a given type, should normally be defined as members of a class

4. Symmetric operations, such as arithmetic operators, equality operators, relational operators, and bit operators. Best defined as a normal non-member function

Operators that cannot be overloaded:

::       .*      . ? :

Basic Attention:

1. member variables are initialized in the same order as they were declared, regardless of the order in the initialization list2The case that must be initialized in the initialization list: Members of class type without default constructors                         &NBSP ;                          ,         &NB Sp;const member variables for type members and reference types                 &NBSP;--&GT;CONST type members call copy constructors and reference types do not invoke Shellfish constructor class B;class a{    friend class b;    public:    A ()     {    &NBSP ;   A_ = 0;        cout << "A ()" << endl;   }    A (int a): A_ (a) &NB Sp   {        cout << "A (int)" << endl;   }    A (const A &s) &NB Sp   {        A_ = s.a_;        cout << "A &" << endl;  &NB Sp }    private:    int a_;}; Class B:public a{    public:        B (a &a2, A &AMP;A3)            : a2_ (A2),            a3_ (A3)     {    }        void Prin ()         {          &NBS P cout << a2_.a_ << "<< endl;       }    private:      &N Bsp A a1_;        A &a2_;        const a a3_;}; int main (int argc, const char *argv[]) {    a A1 (4), A2 (5), A3 (6);//--> A (int) a (int) a (int)     b b (A2, A3);    B.prin ();    return 0;} -Friend class, you can access the private members of Class A

two ways to initialize 3.c++: 1. Direct initialization: Calling constructors2. Copy initialization: Use the = number operator, which is called to the copy constructor4.A A1;fun (a) is copied by the copy constructor when the function parameter or return value is a class type. ---> Call fun (a) calls the copy constructor and, of course, calls the destructor5.The copy constructor is the reason for the reference: prevents the copy constructor from being called indefinitely. A copy constructor of a type is called when copying a constructor, so infinity6.Deep copy shallow copy: Shallow copy: Simple assignment of data members deep copy: For dynamic members in the object, can not be simple assignment, but should be dynamically allocated space7.Spatial C + + objects: Call the base class constructor first, initialize the members on the list, and then call your own constructor---when the destructor is reversed8. Overloaded Overlay Hidden Concepts9. The difference between a conversion constructor and a type conversion function. Type Conversion functions Note the following: 1. member functions, 2. Cannot specify a return type, 3. Cannot have a reference-->operator int ()--in the function to return the same type of out.Polymorphism: Static polymorphism (overloaded (operator). function)) Dynamic polymorphism: virtual functionOne by one .: Use pointers to access non-virtual functions: When you access a pointer's type, use the pointer to visit a virtual function: the type of the object that the pointer refers to---> reference is similar, but the reference cannot be changed once it is declared.Conditions that trigger dynamic binding: 1. virtual function ability to run dynamic Binding 2. A function call must be made through a pointer or reference to a base class type 13. Constructors cannot be virtual: Virtual functions produce different actions for objects of different types, and there are no virtual function pointers. No virtual functions are visited.

13. Dynamic execution-time type recognition (RTTI): typeID Returns a pointer or refers to the actual type of the object being referred to dynamic_cast a pointer to the base class Or a reference to a safe conversion of a pointer to a derived type or reference 14. Explicit Conversions: reinterpret_cast coercion Type conversions--> type conversions similar to C const_cast convert the const attribute or add con The St attribute static_cast Implicit type conversion, the dynamic_cast that can be self-actively converted is mainly used for the downstream conversion with virtual function.

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C + + operator overloading and some basic concepts