C++primer 15.5-day exercise

Exercise 15.18

User code can use derived classes to convert to a base class only if the derived class is public-inheriting the base class: B &tb=D;

Base *p=&d1; Correct, Pub_derv is the public inherit base

p=&d2; Error, Priv_derv is a private inheritance base

p=&d3; Error, Prot_dery is protecting inherited base

p=&dd1; Right, Derived_from_public is the public inheritance in Pub_dery

p=&dd2; Error, Priv_derv is private inherited from base

p=&dd3; Error, Prot_dery is protection inherited from base

Exercise 15.19

1 classBase2 {  3CharPriv; 4 protected:  5intProt; 6  Public:  7voidpub () {}8voidMEMFCN (Base &b) {b = * This; }//correct9 }; Ten structPub_dery: PublicBase One {   A voidMEMFCN (Base &b) {b = * This; }//correct -intF () {returnProt;}  - };  the structProt_dery:protectedBase - {   -voidMEMFCN (Base &b) {b = * This; }//correct - };  + structPriv_dery:PrivateBase - {   +voidMEMFCN (Base &b) {b = * This; }//correct AintF1 () {returnProt;}  at };  - structDfpub: PublicPub_dery - {   -voidMEMFCN (Base &b) {b = * This; }//correctly, a derived class of a public inheritance derived class can access its public and protected parts -intUse_base () {returnProt;}  - };  in structDfpro: PublicProt_dery - {   tovoidMEMFCN (Base &b) {b = * This; }//correctly, a derived class that protects inherited derived classes can access its protection section + };  - structDFPRI: PublicPriv_dery the {   *voidMEMFCN (Base &b) {b = * This; }//error, the base type is inaccessible and does not allow for the conversion of inaccessible base class "base". The reason is that priv_dery is a private inheritance base, so for Dfpri, the base portion of its priv_dery part is private.

Exercise 15.20

See above

Exercise 15.21

C++primer 15.5-day exercise