C + +-class

Class A;

Class Members:

1. Function members

Constructor: A special member function that cannot be declared as a const

The constant pointer this:this type is "a *const" and always points to the "this" object that invokes the member function;

Const member function: Used to modify the type of the implicit this pointer, modified after the this pointer type is "const A *const". Equivalent to the this pointer added " Bottom const", can cause overloading;

The function that returns the This object:

/* Note the return type and the return statement */  & Sales_data::combine (const Sales_data &RHS)    {... return *this;     // Dereference this pointer    }

Const can cause overloading

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2. Data members

Typically encapsulated as in the "private" part, the private part encapsulates (that is, hides) the implementation details of the class.

Variable data member (mutable keyword ): For variable data members, any member function, including the const function, can change its value within.

class screen{public:    voidconst;   // Const member Functions Private :    mutable size_t access;           // Variable data members }voidconst{    ++access;                  // Change Access}

initial value in class : When we provide an initial value in a class, we must use "=" or curly braces.

3. Type Members

class screen{public:    typedef std::string:: Size_type pos;  // type member pos Private :    pos cursor=0;    pos Height=0;    std::string contents;

A class can customize an alias for a type in a class, and the type alias defined by the class has access restrictions (public or private) like other members;

The members used to define the type must first be defined and used, usually where the class begins !

4. Friends

A friend declaration is placed in the same header file as the class itself;

In order for a friend to be visible to the user of the class, the function is specifically declared once outside the class (in addition to the friend declaration inside the class);

Private members of the class can be accessed, and private data members of the class can be overwritten. Abusing a friend destroys the encapsulation of a class.

C + +-class