Knowledge that you must know in C + +

//In-depth understanding of inheritance and the spatial size of virtual functions#include <iostream>using namespace STD;classa{Chara[ -];};classB: Publica{Charb[ -];};classC: Publica{Charc[ -];};classD: PublicB Publicc{Chard[ -];};//virtual inheritance for other classesclassE: Public Virtuala{Chare[ -];};classF: Public Virtualb{Charf[ -];};the method of getting the length of the array with//function parameterTemplate<TypeNameTintN>voidPrintarrlength (T (&AMP;C) [N]) {cout<<"c[] spare mem space is"<<sizeof(C) << Endl;cout<<"c[] length is"<< N << Endl;cout<<"The array typebyte is"<<sizeof(C)/n << Endl;}/ * Detailed explanation virtual inheritance: In the inheritance definition contains the Virtual keyword Inheritance Relationship virtual base class: In the virtual function system, the base class that inherits from virtual, need to notice is: class Csubclass:public virtual CBase { Where CBase is called the virtual base class of Csubclass, rather than saying that CBase is a virtual base class * /structcbaseclass1{CBaseClass1 (size_t N): M_val (n) {} Public: size_t M_val;};structCSubClassV1: Public Virtualcbaseclass1{CSubClassV1 (size_t N): CBaseClass1 (n) {}};structCSubClassV2: Public Virtualcbaseclass1{CSubClassV2 (size_t N): CBaseClass1 (n) {}};structCDIAMONDCLASS1: PublicCSubClassV1, Publiccsubclassv2{CDiamondClass1 (size_t N): CBaseClass1 (n), CSubClassV1 (n), CSubClassV2 (n) {}};structCDIAMONDSUBCLASS1: Publiccdiamondclass1{CDiamondSubClass1 (size_t N): CBaseClass1 (n), CDiamondClass1 (n) {}};//function pointervoidFA () {cout<<"Hello fa"<< Endl; }voidFB () {cout<<"Hello fb"<< Endl; }voidFC () {cout<<"Hello FC"<< Endl; }//define function pointer, return type void, parameter passed to voidtypedef void(*FUNCPTR) (void);//Generate two-dimensional arrays in the heap areavoidNew2darray (intXintY) {int* * p=New int*[y]; for(intI=0; i<y;i++) p[i]=New int[x];intCount=0; for(intI=0; i<x;i++) for(intj=0; j<y;j++) p[i][j]=count++; for(intI=0; i<x;i++) { for(intj=0; j<y;j++)cout<< P[i][j] <<" ";cout<< Endl; }}//test SectionintMain () {///Direct inheritance the size of the space occupied by each class    cout<<"sizeof (A)"<<sizeof(A) << Endl;//100    cout<<"sizeof (B)"<<sizeof(B) << Endl;//200    cout<<"sizeof (C)"<<sizeof(C) << Endl;//200    cout<<"sizeof (D)"<<sizeof(D) << Endl;//500    //For virtual inheritance of the size of the class function space, there are also virtual function pointers    cout<<"sizeof (E)"<<sizeof(E) << Endl;//200+4    cout<<"sizeof (F)"<<sizeof(F) << Endl;//300+4    //For examples of implicit conversions in multiple inheritanced* PD =NewD c* PC =dynamic_cast<C*> (PD); b* PB =dynamic_cast<B*> (PD);cout<< (int)(void*) PC << Endl;cout<< (int)(void*) PB << Endl;cout<< (int)(void*) PC-(int)(void*) PB << Endl;//200    //Test get array length    intp[]={1,2,3,4,5}; Printarrlength (P);//test part of the function pointerFuncptr FP;CharChoosefunc;Cin>> Choosefunc;Switch(Choosefunc) { Case ' A ': fp=&fa; Break; Case ' B ': fp=&fb; Break; Case ' C ': FP=FC; Break;default: Break; }//Don't forget to call here(*FP) ();//test the generation of two-dimensional arraysNew2darray (4,5);return 0;}

Knowledge that you must know in C + +