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Có bốn cách để trộn và đối sánh các con trỏ lớp cơ sở và các con trỏ lớp dẫn xuất với các đối tượng lớp cơ sở và các đối tượng lớp dẫn xuất:

 Tham chiếu tới một đối tượng lớp cơ sở với một con trỏ lớp cơ sở thì không phức tạp.

 Tham chiếu tới một đối tượng lớp dẫn xuất với một con trỏ lớp dẫn xuất thì không phức tạp.

 Tham chiếu tới đối tượng lớp dẫn xuất với một con trỏ lớp cơ sở thì an toàn bởi vì đối tượng lớp dẫn xuất cũng là một đối tượng lớp cơ sở của nó. Như vậy đoạn mã chỉ có thể tham chiếu tới các thành viên lớp cơ sở. Nếu đoạn mã tham chiếu tới các thành viên lớp dẫn xuất thông qua con trỏ lớp cơ sở, trình biên dịch sẽ báo một lỗi về cú pháp.

 Tham chiếu tới một đối tượng lớp cơ sở với một con trỏ lớp dẫn xuất thì có lỗi cú pháp. Đầu tiên con trỏ lớp dẫn xuất phải được ép sang con trỏ lớp cơ sở.

Đa kế thừa (multiple inheritance)

Một lớp có thể được dẫn xuất từ nhiều lớp cơ sở, sự dẫn xuất như vậy được gọi là đa kế thừa. Đa kế thừa có nghĩa là một lớp dẫn xuất kế thừa các thành viên của các lớp cơ sở khác nhau. Khả năng mạnh này khuyến khích các dạng quan trọng của việc sử dụng lại phần mềm, nhưng có thể sinh ra các vấn đề nhập nhằng.

Ví dụ 5.7: Lớp Circle và project có tên là CT5_8.PRJ (gồm các file DIRIVED.CPP, CT5_8.CPP).

File BASE1.H

1: //BASE1.H

2: //Định nghĩa lớp Base1

3: #ifndef BASE1_H

4: #define BASE1_H

5:

6: class Base1

7: {

8: protected:

9: int Value;

10: public:

11: Base1(int X)

12: {

13: Value = X;

14: }

15: int GetData() const

16: {

17: return Value;

18: }

19: };

20:

21: #endif

File BASE2.H

1: //BASE2.H

2: //Định nghĩa lớp Base2

3: #ifndef BASE2_H

4: #define BASE2_H

5:

6: class Base2

7: {

8: protected:

9: char Letter;

10: public:

11: Base2(char C)

12: {

13: Letter = C;

14: }

15: char GetData() const

16: {

17: return Letter;

18: }

19: };

20:

21: #endif

File DERIVED.H

1: //DERIVED.H

2: //Định nghĩa lớp Derived mà kế thừa từ nhiều lớp cơ sở (Base1&Base2)

3: #ifndef DERIVED_H

4: #define DERIVED_H

5:

6: #include "base1.h"

7: #include "base2.h"

8:

9: class Derived : public Base1, public Base2

10: {

11: private:

12: float Real;

13: public:

14: Derived(int, char, float);

15: float GetReal() const;

16: friend ostream&operator<<(ostream&Output, const Derived&D);

17: };

18:

19: #endif

File DERIVED.CPP

1: //DERIVED.H

2: //Định nghĩa lớp Derived kế thừa từ nhiều lớp cơ sở (Base1&Base2)

3: #ifndef DERIVED_H

4: #define DERIVED_H

5:

6: #include "base1.h"

7: #include "base2.h"

8:

9: class Derived : public Base1, public Base2

10: {

11: private:

12: float Real;

13: public:

14: Derived(int, char, float);

15: float GetReal() const;

16: friend ostream&operator<<(ostream&Output, const Derived&D);

17: };

18:

19: #endif

File CT5_8.CPP

1: //CT5_8.CPP

2: //Chương trình 5.8

3: #include<iostream.h>

4: #include "base1.h"

5: #include "base2.h"

6: #include "derived.h"

7:

8: int main()

9: {

10: Base1 B1(10), *Base1Ptr;

11: Base2 B2('Z'), *Base2Ptr;

12: Derived D(7, 'A', 3.5);

13: cout<<"Object B1 contains integer "

14:     <<B1.GetData()<<endl

15:     <<"Object B2 contains character "

16:     <<B2.GetData()<<endl

17:     <<"Object D contains:"<<endl<<D<<endl<<endl;

Questions & Answers

how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
ninjadapaul
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Lập trình hướng đối tượng. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10794/1.1
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