C + +, a combination of classes

1. In Class A The object of Class B is a member variable, called a combination of classes (composition).

2. When combined, the class B is typically initialized in the constructor initialization list of Class A (a constructor of Class B is called).

If Class B is not initialized, a constructor that can pass arguments in class B is called.

#include <iostream>using namespacestd; #include<string>//--------------------------------------classa{ Public:    intM_ax; intM_ay;    A (); A (intValintvy);}; A::a () {}a::a (intVxintvy) {     This->m_ax =VX;  This->m_ay =vy;}//--------------------------------------classb{ Public:    intM_BX;    B (); B (intval);}; B::b () {}b::b (intval) {     This-&GT;M_BX =Val;}//--------------------------------------classc{ Public: A ac;    B BC;    C (); C (intVaxintVayintVBX); C (intVAX,intVay); C (intVBX); voidshow ();}; C::c () {}c::c (intVAX,intVayintvbx): AC (Vax,vay), BC (VBX) {}c::c (intVAX,intvay): AC (Vax,vay) {}
C::c (intvbx): BC (VBX)//non-Initialized internal class object, can not be written out, can also be written outac (). c::c (int vbx): BC (VBX), ac ()

{}voidc::show () {cout<<"Ac.m_ax ="<<ac.m_ax<<Endl; cout<<"Ac.m_ay ="<<ac.m_ay<<Endl; cout<<"BC.M_BX ="<<bc.m_bx<<Endl;}//--------------------------------------intMain () {C C1 (1,2,3 );    C1.show ();  while(1); return 0 ;}//Ac.m_ax = 1//Ac.m_ay = 2//BC.M_BX = 3

C + +, a combination of classes