C + + Learning-Special class members

Static variables:

#include <iostream>#include<string>#include<typeinfo>using namespacestd;classa{ Public: A () {Total++; } Static intTotal ;};//@warn static member variables must be defined globallyintA::total =0; voidMain () {A A1;    A A2; cout<< a1.total<<Endl; cout<< a2.total<<Endl;
cout << a::total << Endl;}

Static member functions:

#include <iostream>#include<string>#include<typeinfo>using namespacestd;classa{ Public: A () {Total++; } Static voidShow () {cout<< Total <<Endl; }    voidEcho () {cout<< Total <<Endl; }Private:    Static intTotal ; intA;};intA::total =Ten; voidMain () {a::show ();    A A1; A1.echo ();

A a1,a2;
A1.echo ();
A1.show ();//You can also call a static function from an object

}

Static member functions and methods are still available after inheritance:

#include <iostream>#include<string>#include<typeinfo>using namespacestd;classa{ Public: A () {Total++; } Static voidShow () {cout<< Total <<Endl; }    voidEcho () {cout<< Total <<Endl; }Private:    Static intTotal ; intA;};classD | Publica{};intA::total =Ten; voidMain () {a::show (); B::show ();}

Static member functions cannot be described as virtual functions

Int (*fun) (int);//Declare a function pointer, the argument to the function is int, the return value is int
Int*fun (int);//Declare a function with a parameter of int and a return value of int type pointer

function pointers use:

#include <iostream>#include<string>#include<typeinfo>using namespacestd;intTest1 (intXinty) {    returnX +y;}intTest2 (intXinty) {    returnX *y;}voidMain () {int(*p) (int,int); P=test1; cout<< P (1,2) <<Endl; P=test2; cout<< P (1,2) <<Endl; }

Array of function pointers:

#include <iostream>#include<string>#include<typeinfo>using namespacestd;intTest1 (intXinty) {    returnX +y;}intTest2 (intXinty) {    returnX *y;}voidMain () {int(*p[2])(int,int) ={test1, test2}; cout<< p[0](1,2) <<Endl; cout<< p[1](2,3) <<Endl; }

C + + Learning-Special class members