12th Week "C + + language Basics" program reading-Multiple inheritance (5)

Problem Description:

(5) Read the definition of the following class, and say the result of a call from a different situation in the test function

<span style= "Font-family:kaiti_gb2312;font-size:18px;color: #ff6666;" ><strong> #include <iostream>using namespace Std;class a{protected:    int a,b;public:    A (int aa, int BB): A (AA), B (BB) {}    void PrintA ()    {        cout<< "a:" <<a<< "\TB:" <<b<<endl;    } };class b:public a{    int c;public:    B (int aa, int bb, int cc): A (AA,BB), C (cc) {}    void Printb ()    {        cout& lt;< "A:" <<a<< "\TB:" <<b<< "\TC:" <<c<<endl;    }}; int main () {    a A ();    b b (2,3,4);    Add the code in the following quiz    return 0;} </strong></span>

(a)

<span style= "Font-family:kaiti_gb2312;font-size:18px;color: #ff6666;" ><strong>    a=b;    A.printa ();    B.printa ();    B.PRINTB ();</strong></span>

What do you think the output is: a:2 B:3 a:2 B:3 a:2 b:3 c:4 The result of running the program is: (b)

<span style= "Font-family:kaiti_gb2312;font-size:18px;color: #ff6666;" ><strong>    b=a;    A.printa ();    B.printa ();    B.PRINTB ();</strong></span>

A compilation error occurs because B inherits a data member that has a a, but not equal to a, data member.
Record the errors and understand the prompts in the IDE:
(c)

<span style= "Font-family:kaiti_gb2312;font-size:18px;color: #ff6666;" ><strong>    A &r1=a;    A &r2=b;    R1.printa ();    R2.printa ();    R2.PRINTB ();</strong></span>

Delete the line where the error occurred;
For the rest of the program, you think the output is: a:1 b:1 a:2 B:3 the actual running output is:The wrong reason for that line is that a &r2=b; R2 is a object that cannot use the member function of B.
(d)

<span style= "Font-family:kaiti_gb2312;font-size:18px;color: #ff6666;" ><strong>    A *p=&a;    P->printa ();    p=&b;    P->printa ();    P->PRINTB ();</strong></span>

Delete the line where the error occurred;
For the rest of the program, you think the output is: a:1 b:1 a:2 B:3
The actual running output is: the wrong reason for that line is that p is a pointer to a object, because B inherits a so it can execute p=&b; P->printa (); But there is no printb () in a, so p->printb (); error cannot be performed. (E)
Add member functions in Class A:

<span style= "Font-family:kaiti_gb2312;font-size:18px;color: #ff6666;" ><strong>    int Geta () {return A;} </strong></span>

add a general function before the main function:

<span style= "Font-family:kaiti_gb2312;font-size:18px;color: #ff6666;" ><strong>void f (A x) {    cout<< "Aaaaah, my A:" <<x.geta () <<endl;} </strong></span>

The specified part of the main function is:

<span style= "Font-family:kaiti_gb2312;font-size:18px;color: #ff6666;" ><strong>    F (a);    F (b);</strong></span>

What do you think the output is: Aaaaah, my a:1 Aaaaah, my a:2 The result of running the program is:

12th Week "C + + language Basics" program reading-Multiple inheritance (5)