Bài giảng lập trình hướng đối tượng dùng c chương 4 tính kế thừa

Chương 4. Kế thừa lớp
đối tượng



Cập nhật: 15 tháng 03 năm 2013
#2
Nội dung

 !"#$%

$#$&'#$%

$(')*+,-.#$%
#3
Đặt vấn đề
/012345+6.&'78-)9
 7: 45+ 6. ;. <. " ! 3 * = .5 ). ) (' .)+
>?@A@>BBC
7:45+6.;.<.D0EFG=".)+.H
IF'0%>CJ,KFL
#4
Đặt vấn đề
Cch 1:M1N&'78-'OP'&+F:*&'78,-.;.
<.,FM1N)#Q,RSK.2$ST.,U#G
1<.&'78KN.J.D
4
#5
Đặt vấn đề
Cch 2:V5+6.&'78&2=('&&'78W!X.;
Cch 3:M-Y'&'782QN-&'78&)2G1N-+F:

*ST.,UG#H-6 *X.#K,=.Z('(Z
5
#6
Đặt vấn đề
7:GT$-'Y'#-&'78&)&'78[&>W
12JJ.
#7
Đặt vấn đề
ST.6-ST.,U2,-Z\S&.,F+"]D5\2SP
4S>2Q#E6I78LS.]D5\G^.2_2Q#
8-(+:1<.&'78J.)12J=W':;
#X.'0WX.;2Q45+6.N%2:
7
#8
Khái niệm
8
$%-'Y'#->&'`)>&'a4b%&'c2G`dGb
0=")2_2Q*cZ ),`GQGF^.="
)^.)2=.&
#9
Khái niệm
9

$%Q #0H.1<.&'232SP2e.f

7GQ2e.f&'2WSP.&6,F>+!&'2WSP.23G
g

h&'Gg2SP.i)&'TKIL)&'#$%2SP.i)&'
a4bI,L

#10
Khái niệm
10
A B

j"b.
k"b*c
l"
b*`
-
- *- - - *- *- - *
- - *
+ * + + + * + * + * + + +
* +
C
A B

-
- - - - - - - - - + + + + + + + + + +
* * * * *
#11
Ký hiệu
11

ch),S\.P'J.D*`

`h),S\.P'2_ *c
A
B
A

B C

ch),S\.P'J.D*`)7

`Z7h),S\.P'2_ *c
#12
VD: Lớp ngày cho ngân hàng và sinh viên
12
CDate
CDateNH CDateSV
#13
Khai báo
13
Fh&'7
m
=")'ST.;*&'
n
Fh&'8aVbFh&'7
m
=")'ST.;J.* &'a4b
n
#14
Khai báo
14
7Go2Q2e.f)2=.J.-'ST.;23GgK&'
,-.&'a4bI'ST.;&'a4b,O.F&'ST.;&'L

8O.%#G

8O.%#G,)-,,

#15
Khai báo – Dùng từ khóa new
15
7pMp
m
',-#Q>q
',-#Qoq
'-->IL
mn
'--oIL
mn
n
8cVrc7pMp
m
',#QAq
'-->IL
mn
'--?IL
mn
n
#16
Khai báo – Dùng virtual & override
7pMp
m
',-#Q>q
',-#Qoq
',-->IL
mn
',--oIL
mn

n
8cVrc7pMp
m
',#QAq
'-,,-->IL
mn
'--?IL
mn
n
#17
Ví dụ
17
s$ST.,U('4b5FZ$,t..uo-N5F5FF$)
5FP'2u.X.*5F.u3WZiF

5FF$GX.,F.)(ST.

5FP'2u.GX.,F.)W.\)
#18
Ví dụ
18
G5+#$%
CNHANVIEN
CHOPDONGCBIENCHE
#19
VD dùng từ khoá new
19
7cs
m',--q
',-,.-q

'-'IL
m7--,Iv'-vLq
-wx,I7--hILLq
7--,Iv'-vLq
-w7--hILq
n
'-VIL
m7--,hIv-mynz-m>nvZ-Z-Lq
n
n
#20
Ví dụ – Dùng từ khoá new
20
class CBIENCHE : CNHANVIEN
{
private oat hesoluong;
public new void Nhap()
{ base.Nhap();
Console.Write("Nhap he so luong: ");
hesoluong = oat.Parse(Console.ReadLine());
}
public new void Xuat()
{ base.Xuat();
Console.WriteLine("He so luong: " + hesoluong);
}
}
#21
Ví dụ – Dùng từ khoá new
21
7px8p/7cs

m',{- -q
'-'IL
m'ILq
7--,Iv'-.-vLq
 -w{-x,I7--hILLq
n
'-VIL
mVILq
7--,hIvM-.-vl -Lq
n
n
#22
Ví dụ – Dùng virtual & override
22
7cs
m',--q',-,.-q
',-'IL
m7--,Iv'-vLq
-wx,I7--hILLq
7--,Iv'-vLq
-w7--hILq
n
',-VIL
m7--,hIv-mynz-m>nvZ-Z-Lq
n
n
#23
Ví dụ – Dùng virtual & override
23
7`77cs

m
',{---.q
'-,,-'IL
m'ILq
7--,Iv'--.vLq
--.w{-x,I7--hILLq
n
'-,,-VIL
mVILq
7--,hIv--.vl--.Lq
n
n
#24
Ví dụ – Dùng virtual & override
24
7px8p/7cs
m',{- -q
'-,,-'IL
m'ILq
7--,Iv'-.-vLq
 -w{-x,I7--hILLq
n
'-,,-VIL
mVILq
7--,hIvM-.-vl -Lq
n
n
#25
Ví dụ - Sử dụng phương thức trong Main()
25

-I,.|},.L
m7`7w7`7ILq
'ILq
7px8p/w7px8p/ILq
'ILq
7--,hIvzvLq
VILq
7--,hIvz-'-.vLq
VILq
n