C + + class inheritance-small note

classa{ Public: A () {print1 ();}//The call to virtual function inside the constructor itself is not correct, this is only for testing    Virtual voidprint1 () {std::cout<<"A print1"<<Std::endl; }};classD | Publica{ Public:    Virtual voidprint1 () {std::cout<<"B print1"<<Std::endl; }};classc{ Public:    Charch; Virtual voidPrint2 () {std::cout<<"C Print2"<<Std::endl; }};classB | PublicA Publicc{ Public:    intcd; Virtual voidprint1 () {std::cout<<"D print1"<<Std::endl; }    Virtual voidPrint2 () {std::cout<<"D Print2"<<Std::endl; }};intMain () {//Q1b b;//Output A print1//Q2Std::cout <<sizeof(D) <<std::endl;// -    return 0;}/*A1: The reason for output a print1 is that in the constructor of Class A, the constructor of object B has not been executed internally, so object B has not been initialized and there is no virtual function table, in the construction method of a The this pointer is a type,
So is the memory layout of the PRINT1//A2A that calls A is----------__vfptr = 0x00c0ae48 Const A:: ' vftable ' {for ' a '}----------C memory layout----------__vfptr = 0x00c0abd8 Const C:: ' vftable ' {for ' c '}ch = 0XCCCCCCCC----------D memory layout---------A = {__vfptr = 0x00c0ae48 const D:: ' Vftabl E ' {for ' A '}}b = {__vfptr = 0x00c0abd8 const D:: ' vftable ' {for ' C '} ch = 0xcccccccc}CD = 0XCCCCCCCC---------

So sizeof (D) = 4 + 8 + 4 (the size of C is 8 because memory has to be on it)*/

C + + class inheritance-small note