Class

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Resolvers (::)

Pure '::' resolves to global

void f(){} // Global f();

class A{
public:
    void f(){
        ::f(); // Call global f();
    }
};

Ctors

If a ctor with argument is defined, default ctor will not be generated automatically.

class A{
public:
    A(int x){}
};

A a; // Compile error. No default ctor

Constant object

Constant object can only call constant functions:

void func() const ;

Constant members

Has to be initialized in the ctor's list.

Compile time constants

Needs to be static and const.

static const member needs not be declared outside the class and can be assigned inside the class.

class A{
    static const int size = 10;
    int arr[size];
};

Inline

inline in c++ means multiple definition is allowed (in linking multiple compile units).

multiple definition still not allowed in compiling.

Put inline functions' body in the header file.