Static member function (object-oriented static keyword)

Static member functions

As with static data members, we can also create a static member function that serves the entire service of a class rather than the specific object of a class. Static member functions, like static data members, are internal implementations of the class and are part of the class definition. Ordinary member functions generally imply a this pointer, which points to the object of the class itself, because ordinary member functions are always specific to the specific object of a class. Typically, this is the default. such as the function fn () is actually THIS->FN (). However, compared to a normal function, a static member function does not have the this pointer because it is not associated with any object. In this sense, it cannot access non-static data members that belong to a class object, nor can it access a non-static member function, which only calls the rest of the static member functions. Here is an example of a static member function.

1#include <iostream>2 using namespacestd;3  4 classMyClass5 {6  Private:7       intA, B, C;8       Static intSum//declaring a static data member9  Public:TenMyClass (intAintBintc); One       Static voidGetsum ();//declaring a static member function A }; -  - intMyclass::sum =0;//defining and initializing static data members theMyclass::myclass (intAintBintc) - { -       This->a =A; -       This->b =b; +       This->c =C; -sum + = A+b+c;//non-static member functions can access static data members + } A  at voidMyclass::getsum ()//implementation of static member functions - { -       //cout<<a<<endl;//error code, a non-static data member -cout<<"sum ="<<sum<<Endl; - } -  in intMain () - { toMyClass M (1,2,3); + m.getsum (); -MyClass N (4,5,6); the n.getsum (); * myclass::getsum (); $ Panax Notoginseng       return 0; -}

For static member functions, you can summarize the following points:

• A function definition that appears outside the class body cannot specify a keyword static;

• Static members can access each other, including static member functions to access static data members and access static member functions;

• Static member functions and static data members can be accessed arbitrarily by non-static member functions;

• Static member functions cannot access non-static member functions and non-static data members;

• Because there is no additional overhead for this pointer, the static member function has a slight increase in speed compared to the global function of the class;

• Call a static member function to call a static member function with the member access operator (.) and (-) for a class object or a pointer to a class object, or you can use the following format directly:

< class name >::< static member function name > (< parameter table >)

Invokes the static member function of the class.

Static member function (object-oriented static keyword)