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C HAPT E R 3
Chapter
8
Data Abstractions
J. Glenn
Glenn Brookshear
Brookshear
J.
蔡文能
1
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Slide 8-1
Chapter 8: Data Abstractions
•
•
•
•
•
•
8.1 Data Structure Fundamentals
8.2 Implementing Data Structures
8.3 A Short Case Study
8.4 Customized Data Types
8.5 Classes and Objects
8.6 Pointers in Machine Language
– See the Assembly code: tcc -S file.c
gcc -S file.c
g++ -S file.cpp
2
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Slide 8-2
Basic Data Structures
• Homogeneous array
– Row major: Pascal, C/C++, Java, C#
– Column major: FORTRAN
• Heterogeneous array: struct/class [, union]
• Sequence
– List : ArrayList, LinkedList
– Stack (in Java, a Stack is a Vector)
– Queue
• Tree
Data Structures: How to arrange data in memory
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Slide 8-3
Arrays vs. Struct (including class)
• Homogeneous arrays
– Row-major order versus column major order
– Address polynomial for each of them
• Heterogeneous arrays (class, struct)
– Components can be stored one after the other in a contiguous
block
– Components can be stored in separate locations identified by
pointers
 Give a formula for finding the entry in the i-th row and
the j-th column of a two-dimensional array if it is stored
in column major order rather than row major order.
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Slide 8-4
Array allocation: Row major vs. Column major
• Column major (column by column)
– FORTRAN: integer*4 m(3,6)
在 2010
在 2014
1
2
3
4
5
6
1
0
2
1
3
2
FORTRAN
用小括號
• Row major (row by row)
– Pascal, C/C++,Java
– int m[3][6];
– Subscript 從 0 開始
m(2,4)
在 何位址?
m[1][3]在 何位址?
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Slide 8-6
Column-major order (FORTRAN)
The array is stored as a sequence of arrays
consisting of columns (column by column)
Integer*4 M(2,7)
1
1
2
3
4
5
6
7
M(1,1)
M(2,1)
M(1,2)
M(1,2)
2
x(2,4)
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Slide 8-7
Figure 8.6 A two-dimensional array with four rows and
five columns stored in row major order
須知道每列(row)有幾欄(column)
才能算出下列從何處開始安排
 Give a formula for finding the entry in the i-th row and
the j-th column of a two-dimensional array if it is stored
in column major order rather than row major order.
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Slide 8-8
Row-major order: Pascal, C/C++, Java,C#
The array is stored as a sequence of arrays
consisting of rows (row by row)
int x[2][7]; // declare as 2 rows x 7 columns
x
0
0
1
1
2
3
4
5
6
X[0][1]
X[0][0]
X[0][1]
X[0][2]
X[1][3]
* 在我之前有幾個元素 ?
* 每個元素佔幾個 address? (現代電腦大多一byte一個address)
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Slide 8-9
Accessing elements in 2D arrays (1/2)
int x[m][n];




m, n should be constant in
most languages
m=number of rows
通常用
u=0, v=0
n=number of columns
b=address of x[u][v]
Address of x[i][j] (row major order) is
b + ((i-u)*n + j-v) * (size of entry)
寫個C/C++小程式然後 gcc -S file.c 或 g++ -S file.cpp
編譯成 Assembly code 研究
Brookshear page 306
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Slide 8-10
Accessing elements in 2D arrays (2/2)
The formula for finding the address of an element is
i = b + s*n
s*n
e
k
n’
=
=
=
=
s*e*k + s*n’ = s*(e*k + n’)
number of elements in a row or column
number of rows or columns to be skipped
the number of elements between the target
element and the beginning of a row or column
where b = base address
s = size of each element
n = the number of elements between the
target element and the base address
* 在我之前有幾個元素 ?
* 每個元素佔幾個 address? (現代電腦大多一byte一個address)
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Slide 8-11
e*k + n’ = 6
skip 6 elements
Example
Row-major order: e = 4, k = 1, n’ = 2
Column-major order: e = 3, k =2, n’ =
e*k + n’ = 7
skip 7 elements
1
在
我
之
前
有
6
個
在我之前有 7 個
0
1
2
0
Base address
3
target
element
1
2
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Slide 8-12
Dynamic Array ?
• Most Languages do NOT support dynamic array
 Use pointer in C/C++
int *p;
p = new int[ numberOfElementsNeeded ];
Q: C++ STL 的 vector 如何“自動長大” ?
 In Java, array is an object; create it dynamically!
int p[ ]; // p is only a reference
p = new int[ numberOfElementsNeeded ];
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Slide 8-13
Represent the data and Store the data
Primitive data: (大部份電腦用硬體就可處理的)
bit, byte, word, double word, quad word
C: char, short, int, long, float, double, [long double],
and pointer of any data type
C++: bool, + ALL types in C
Java: boolean, byte, char(16 bits), short(16 bits)
 int(32 bits), long(64 bits), float(32 bits), double(64 bits)
Abstract data (User defined data type):
List, Deque, Stack, Queue, Tree, …
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Slide 8-15
結構與型別 (如何自定資料結構?)
solution: struct
• 只能用前述基本 data type 嗎?
• User defined data type?
•考慮寫程式處理全班成績資料, 包括加總平
均並排序(Sort)然後印出一份照名次排序的
以及一份照學號排序的全班資料
–如何做 Sort (排序) ?
–Sort 時兩學生資料要對調, 要如何對調?
–有很多 array ? 存學號的 array, 存姓名的
array? 存成績的 array? …
Bubble sort, Insertion sort, Selection sort
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Slide 8-16
So, Why using struct in C ?
Why using class in C++ ?
• Struct 可以把相關資料 group 在一起
struct student x[99], tmp;
/* … */
tmp = x[i]; x[i] = x[k]; x[k] = tmp;
•
•
•
•
增加程式可讀性
程式更容易維護
其實都不用到 struct 也能寫出所有程式!
How to define / use struct ?
– Next slides
User defined data type is a template for a heterogeneous structure
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Slide 8-17
User-defined Data Type
#include <stdio.h>
考慮寫個程式處理學生的成
績資料, 如何表示一個學生的
struct Student {
資料? 想一想. . .
long sid;
char name[9]; /*可存四個Big5中文 */
float score[13]; /*每人最多修13 科 */
};
/*注意struct與class之 分號不能省掉*/
習慣上第一個字母大寫
int main( ) {
struct Student x; /* C++ 和 C99 不用寫 struct */
x.sid = 123; /* dot notation */
strcpy(x.name, "張大千") ; /*注意字串不能= */
/* 用 loop 把成績讀入 x.score[?] */
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}
//C 的字串不能直接用 = 複製! 也可用 memcpy( )
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Slide 8-18
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Dynamic Data Structures
• Static Data Structures: Size and shape of data
structure does not change
• Dynamic Data Structures: Size and shape of data
structure can change at Run time (How?)
• Pointers: An integer which is a memory address
points to some data unit. For example: the program
counter in the CPU. (Intel CPU uses CS:IP)
x
pointer
6087
The pointer points to memory cell x
which contains the value 6087.
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Slide 8-19
Sequence
• A group of elements in a specified order is called a
sequence.
• A tuple is a finite sequence.
– Ordered pair (x, y), triple (x, y, z),
quadruple, and quintuple
– A k-tuple is a tuple of k elements.
• List, Stack, Queue , Deque, Vector all are sequence
data structures that their size may vary.
20
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Slide 8-20
Figure 8.1 Lists, stacks, and queues
C++ STL, Java 都有提供 iterator 可走遍整個資料結構
An iterator is an object that enables a user to loop through
a collection without accessing the collection’s fields.
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Slide 8-21
Lists
• A list is a collection of entries that appear in sequential order.
• Can be an ArrayList or be a LinkedList.
– ArrayList: List stored in a homogeneous array; also known as
Contiguous list
– LinkedList: List in which each entries are linked by pointers
• Head pointer: Pointer to first entry in list
• NIL pointer: A “non-pointer” value used to indicate end of list
(NULL or 0)
• List in C++ STL vs. List in Java
– In C++ STL, list is a template class which implements as a linked list
– In Java, java.util.List is a interface which extends from
java.util.Collection interface;
java.util.ArrayList and java.util.LinkedList both implements List
interface and thus they are both Lists.
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Slide 8-22
ArrayList -Contiguous Storage of a List
• List entries are stored consecutively in memory :
ArrayList
• Advantage: simple, quick random access
• Disadvantage: insertion and deletion difficult.
Java.util.ArrayList is NOT a Queue because it does NOT
implement java.util.Queue interface;
However, java.util.LinkedList is a Queue and thus the
following statement is correct:
Queue<Integer> gg = new LinkedList<Integer> ( );
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Slide 8-23
Linked Lists
 Each list entry contains a pointer to the next


entry
List entries can be stored in any part of memory.
There is a special head pointer for the first entry
and a Nil pointer in the last entry.
java.util.LinkedList is a Queue and thus the following
statement is correct:
Queue<Integer> gg = new LinkedList<Integer> ( );
However, the following is WRONG !
Queue<Integer> gg = new ArrayList<Integer> ( ); // wrong
In JDK 1.5, LinkedList implements Queue;
In JDK 1.6, it implements Deque which extends Queue
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Slide 8-24
Figure 8.9 The structure of a linked list
Singly LinkedList
Java 的 LinkedList 與 C++ STL 的 list 都是doubly linked list
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Slide 8-25
Figure 8.10 Deleting an entry from a linked list
Singly LinkedList
Figure 8.11 Inserting an entry into a linked list
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Slide 8-26
Inserting an entry into a
doubly linked list
head
p
共有四個 Link 要改 !
Add before this node
head
What about delete ?
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tmp
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p
27
Slide 8-27
Stacks
• A stack is a list in which all deletions and insertions
occur at the same end.
• Alternative name: LIFO structure
– Last In First Out
• Top: place where insertions and deletions occur.
• Base: opposite end to the top.
• Insertion=push, deletion = pop.
A stack in memory
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Slide 8-28
Stacks and Procedures/Functions Call



When a procedure P is called a pointer to the return
location is pushed onto a stack.
If a second procedure Q is called from P then a pointer to
the return location for Q is pushed onto the same stack.
When a procedure finishes, the return location is popped
from the stack.
tcc –S filename.c
tcc –S filename.cpp
gcc –S filename.c
g++ –S filename.cpp
注意gcc/g++ 翻譯出的
組合語言格式與 Intel 公佈的或
是Microsoft MASM 格式不同!
除了指令名稱略不同外,
指令中運算元(operands)的
左右順序相反!
29
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Slide 8-29
C++ STL stack contains a deque [, vector, list ]
template <class T, class T38=deque<T> > class stack {
protected: T38 c; // the actual data is here
public:
typedef typename T38::value_type value_type;
typedef typename T38::reference reference;
typedef typename T38::const_reference const_reference;
stack( ):c( ) { }
explicit stack(const T38& seq) : c(seq) { }
bool empty( ) const { return c.empty( ); }
int size( ) const { return c.size ( ); }
reference top( ) { return c.back( ); }
const_reference top( ) const { return c.back( ); }
void push(const value_type& x) { c.push_back(x); }
void pop( ) { c.pop_back( ); }
}; // class stack
stack<int> gg;
stack<int, vector<int> > yy;
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Slide 8-30
Stack in java.util.*;
package java.util;
public class Stack<E> extends Vector<E> {
public Stack() { }
public boolean empty() { return size( ) == 0; }
public E push(E item) { addElement(item); return item; }
public synchronized E pop( ) {
E obj; int len = size( );
obj = peek( );
removeElementAt(len - 1);
return obj;
}
public synchronized E peek( ) {
int len = size( );
if (len == 0) throw new EmptyStackException();
return elementAt(len - 1);
}
public synchronized int search(Object o) {
int i = lastIndexOf(o);
if (i >= 0) { return size( ) - i; }
return -1;
}
private static final long serialVersionUID = 1224463164541339165L;
} // class Stack
31
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Vector in java.util.*;
package java.util;
public class Vector<E> extends AbstractList<E> implements List<E>,
RandomAccess, Cloneable, java.io.Serializable {
protected Object[ ] elementData; // Java 的參考是類似C 的指標
protected int elementCount;
protected int capacityIncrement; // if 0, double the capacity (array length)
private static final long serialVersionUID = -2767605614048989439L;
public Vector(int initialCapacity, int capacityIncrement) {
super( ); // invoke constructor of my father
if (initialCapacity < 0)
throw new IllegalArgumentException("Illegal Capacity: "+
initialCapacity);
this.elementData = new Object[initialCapacity];
this.capacityIncrement = capacityIncrement;
}
public Vector(int initialCapacity) { // default increment 0 will double capacity
this(initialCapacity, 0);
}
public Vector( ) { this(10); } // Default capacity is 10
public synchronized int size( ) { return elementCount; }
// . . .
32
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Slide 8-32
Stack 應用 again
• 使用堆疊把 infix  postfix
– Stack 內放運算符號和左括號, 注意優先權
– Operand 直接輸出
• 使用堆疊計算 postfix 的答案
– Stack 內放 operand 值 (value, 整數或實數)
– 遇到 operator 就把 operand pop出來算
– 算出的 value 再 push 進去
33
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Slide 8-33
Handling Pointers
struct Student {
long x;
struct Student * next;
};
struct Student * p;
p
long x
next
 Assign the value 4 to x:
p->x = 4; // C, C++
p.x = 4; // Java, C#
 Initialise a pointer q to point to the next item:
q = p->next; // C, C++
q = p.next; // Java
34
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Slide 8-34
Figure 8.19 A procedure for printing a
linked list
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Slide 8-35
Print a Linked List in Reverse Order
Procedure reverseprint(L)
p = head(L)
While p<>Nil do
push(p.data, stack)
p=p.next
EndWhile
While stack not empty
Print(pop(stack))
EndWhile
End Procedure
36
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Slide 8-36
Queue
• A queue is a list in which insertions are
performed at one end (tail) and deletions are
performed at the opposite end (head).
• FIFO: First In, First Out
tail: insertions
tail pointer: to next unused location
head: deletions
head pointer: to head item
37
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Slide 8-37
Circular Queue empty vs. full
EMPTY QUEUE
[3]
[2]
[2]
[3]
J2
[1]
[4]
[0]
J3
[1] J1
[5]
[4]
[0]
front = 0
rear = 0
[5]
front = 0
rear = 3
What if Queue is full ?
40
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Slide 8-40
Leave one empty space when Queue is full
Why?
FULL QUEUE
FULL QUEUE
[2]
[3]
J2
[1]
[2]
[3]
J8
J3
J9
J4 [4][1] J7
J1
J5
[0]
[5]
front =0
rear = 5
How to test when queue is empty?
How to test when queue is full?
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[4]
J6
[0]
J5
[5]
front =4
rear =3
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Slide 8-41
Enqueue in a Circular Queue
void enqueue(int front, int *rear, element item)
{
/* add an item to the queue */
*rear = (*rear +1) % MAX_QUEUE_SIZE;
if (front == *rear) /* reset rear and print error */
return;
}
queue[*rear] = item;
}
42
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Slide 8-42
Dequeue from Circular Queue
element dequeue(int* front, int rear)
{
element item;
/* remove front element from the queue and put it in item */
if (*front == rear)
return queue_empty( );
/* queue_empty returns an error key */
*front = (*front+1) % MAX_QUEUE_SIZE;
return queue[*front];
}
43
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Slide 8-43
Trees
Earth
Europe
UK
Africa
Asia
France Chad
China
Paris
Beijing
London
S. America
India
Peru
N. America
USA
Lima
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Slide 8-44
Figure 8.2 An example of an organization chart
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Definition of a Tree
• A tree is a connected undirected graph in which
there are no circuits.
• A rooted tree is a tree in which one node is
selected as the root.
• In computing, trees are usually rooted.
46
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Terminology
•
•
•
•
•
Node, root, leaf, terminal node, parent, child.
Ancestor: Parent, parent of parent, etc.
Descendent: Child, child of child, etc.
Siblings: Nodes sharing a common parent
Subtree: a node together with all the nodes
below it.
• Depth: number of nodes on longest path from
root to a leaf.
• Binary tree: each node has at most two children.
47
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Figure 8.3 Tree terminology
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Binary Trees
• A binary tree is a finite set of nodes that is
either empty or consists of a root and two
disjoint binary trees called the left subtree
and the right subtree.
• Any tree can be transformed into binary tree.
– by left child-right sibling representation
• The left subtree and the right subtree are
distinguished.
49
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Slide 8-49
Samples of Binary Trees
Complete Binary Tree
B
B
B
3
D
C
E
G
F
4
4
E
A
2
Skewed Binary Tree
歪斜樹
C
D
1
A
A
H
I
5
What is a Full Binary Tree ?
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Slide 8-50
Figure 8.16 The conceptual and actual
organization of a binary tree using a linked
storage system
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Figure 8.17: A tree stored without pointers
適合大部份 node 都存在的 tree : complete tree, full tree
52
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Figure 8.18: A sparse, unbalanced tree shown in
its conceptual form and as it would be
stored without pointers
大部份空間都浪費掉了!
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Slide 8-53
Recursive Printing of a Binary Tree
Procedure printTree(tree)
If (tree not empty)
printTree(left subtree)
print(root)
printTree(right subtree)
EndIf
EndProcedure
In-order, pre-order, post-order traversal
54
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Slide 8-54
A procedure for printing the data in a binary
tree (pre-order Traversal)
void printTree(Node root)
{
if(root != NULL ) {
printTheRoot(root);
printTree(root.left);
printTree(root.right);
}
}
55
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Slide 8-55
A procedure for printing the data in a
binary tree (post-order Traversal)
void printTree(Node root)
{
if(root != NULL ) {
printTree(root.left);
printTree(root.right);
printf(root.data);
}
}
56
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Inserting the entry M into the list
B, E, G, H, J, K, N, P stored as a binary search tree
57
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Slide 8-57
A procedure for inserting a new entry in a list
stored as a Binary Search Tree
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Slide 8-58
Representation of Trees (1/2)
• List Representation
– ( A ( B ( E ( K, L ), F ), C ( G ), D ( H ( M ), I, J ) ) )
– The root comes first, followed by a list of sub-trees
data
link 1 link 2 ...
link n
How many link fields are
needed in such a representation?
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Slide 8-59
Representation of trees (2/2)
data
left child right sibling
A
F
E
K
D
C
B
G
H
I
J
M
L
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Slide 8-60
Binary tree representation of tree
Left Child - Right Sibling
data
left child right sibling
A
F
E
K
D
C
B
G
H
I
J
M
L
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Slide 8-61
Left child-right child tree representation of a tree
A
B
C
E
F
K
D
G
H
L
M
往右下角拉 
I
J
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62
Slide 8-62
Abstract Data Type (ADT)
• A user-defined data type with procedures/functions
for access and manipulation
• Abstract Data Type in Object Oriented Languages
has these features:
– Characteristics can be inherited
– Contents can be encapsulated
– Constructor methods to initialize new objects
• To define an ADT
– C++: struct, class
– Java, C#: class
把 data 以及對 該些 data 有關的方法(method)或稱函數(function, 函式))
封裝(encapsulate)在一個程式單元(例如class)內方便使用
Why using Class?
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63
Slide 8-63
ADT --- Data Abstraction
• An Abstract Data Type (ADT) is a user-defined
data type that satisfies the following two
conditions: (Encapsulation + Information Hiding)
– The representation of, and operations on, objects of the
type are defined in a single syntactic unit; also, other
program units can create objects of the type.
– The representation of objects of the type is hidden
from the program units that use these objects, so
the only operations (methods) possible are those
provided in the type's definition which are known as
interfaces.
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Slide 8-64
What does Abstraction mean?
• Abstraction means ignoring irrelevant features,
properties, or functions and emphasizing the
relevant ones...
“Relevant” to what?
• ... relevant to the given project (with an eye to
future reuse in similar projects).
例如, Button 就只注意 Button 該有啥屬性,
Button 該有哪些函數可以用? 先不管其它不相干的!
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Slide 8-65
Abstraction Example (1/2)
•Example from javax.swing.*;
public abstract class AbstractButton
Fields:
protected ButtonModel model
etc.
The data model
that determines the
button’s state
Methods:
void addActionListener (ActionListener l);
String getActionCommand( );
Apply to any button:
String getText( )
“regular” button, a
etc.
checkbox, a toggle
button, etc.
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Slide 8-66
Abstraction Example (2/2)
java.lang.Object
|
+--java.awt.Component
|
+--java.awt.Container
|
+--javax.swing.JComponent
|
+--javax.swing.AbstractButton
Extends features
of other abstract
and concrete
classes
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Class vs. Object (1/2)
• 討論用class製作 stack 之前先認識object與class
– object 就是“東西”, 就是以前的“變數”
– class 就是“類別”, 某種東西的型別(type)
int m, n; /* int 是整數類別 */
/* m, n 都是變數 */
Student x, y; /* Student 是我們自訂類別 */
/* x, y 都是 object */
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Slide 8-68
Class vs. Object (2/2)
• object is an instance of some class
• 文法上, C++的class 就是以前的 struct
class Student { public:
/* …與寫 struct 同 */
};
struct Node { private:
/* …與寫 class 同 */
}; // Java 已經取消 struct
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Slide 8-69
Object Concept (1/3)
• Why using class
– 支援 OOP (物件導向Object Oriented Programming)
– 又譯作 個體導向程式設計
– 考慮 Stack 堆疊 : 讓東西用起來更像東西
• ADT (Abstract Data Type)抽象資料型別
– 把 data 以及對 該些 data 有關的方法(method)
或稱函數(function, 函式))封裝(encapsulate)在一
個程式單元(例如class)方便使用
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Object Concept (2/3)
• Object-Oriented Analysis (OOA)
– Goal: Understand the domain
• Object-Oriented Design (OOD)
– Goal: Design a solution, a model of the domain in which the
desired activities occur
• Object-Oriented Programming (OOP)
– Goal: Implement the solution
• Note: A Good Design is 2/3 Before You Hit the
Keyboard
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Slide 8-71
OO concept (3/3)
#include "mystk.h"
以用物件方式使用堆疊
#include <iostream.h>
int main( ) {
Stack xo;
/* xo is an object, it is a Stack */
xo.push(880);
/* 要求 xo 把 880 push 進去 */
xo.push(770);
xo.push(53);
while(! xo.isempty( ) ) {
cout << " " << xo.pop( ); /* 要求 xo 吐出頂端元素 */
/* .. .. .. */
} cout << endl;
return 0;
How to? 如何製作 Stack?
}
請看稍後投影片 ..
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Slide 8-72
Stack -- class example ( 1/2) mystk.h
class Stack {
// private:
long data[99]; /* 直接寫 99 不是好習慣*/
int sptr;
標準程式庫的堆疊是stack
public:
注意是小寫! 且其 pop( )是 void
Stack( ) ; /* constructor */
void push( long );
標準程式庫是empty
long pop( );
bool isempty( );
}; /* class Stack */ // 注意右大括號後之分號 ;
bool 要新版的 C++ 才有, 如果不能用就改用 int
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Slide 8-73
Stack -- class example (2/2) mystk.cpp
#include "mystk.h"
#include <iostream.h>
Initialization 工作
要寫在特殊函數
Stack::Stack( ) { sptr = -1; } /*Constructor*/
void Stack::push( long xx) { /*注意 Stack:: */
data[ ++sptr ] = xx;
}
long Stack::pop( ) {return data[sptr--];}
bool Stack::isempty( ) { return sptr == -1;}
// . . .
bool 要新版的 C++ 才有
這是實作出 Stack, 前面 mystk.h只是宣告
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Slide 8-74
Stack (使用) 如何執行?
#include "mystk.h"
gcc mymain.cpp mystk.cpp
#include <iostream.h>
./a.out
int main( ) {
Stack xo, brandy;
gcc –c mystk.cpp
xo.push(880);
gcc mymain.cpp mystk.o
xo.push(770);
xo.push(53);
./a.out
while(! xo.isempty( ) ){
cout << " " << xo.pop( );
} cout << endl; /* new Line*/
53 770 880
return 0;
}
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Slide 8-75
OO features
Encapsulation
Information Hiding The concept of abstraction is
fundamental in programming
抽象化的概念以前就
有: 函數/副程式
Subprogram / function
增加:
Inheritance
Polymorphism
 process abstraction
ADT
 Data abstraction
Software Reuse
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Slide 8-76
Encapsulation and information hiding
• Encapsulation means that all data members (fields) of a class are declared
private. Some methods may be private, too.
• The class interacts with other classes (called the clients of this class) only
through the class’s constructors and public methods.
• Constructors and public methods of a class serve as the interface to class’s
clients.
• Ensures that structural changes remain local:
– Usually, the structure of a class (as defined by its fields) changes
more often than the class’s constructors and methods.
– Encapsulation ensures that when fields change, no changes are
needed in other classes (a principle known as “locality”).
• Abstraction and encapsulation are helpful for the following:
Team development, Reusable software, Easier program
maintenance.
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Slide 8-77
Abstract Data Type Binary_Tree (1/2)
Node Structure in
a Binary Tree
data
left child pointer
right child pointer
structure Binary_Tree(abbreviated BinTree) is
objects: a finite set of nodes either empty or
consisting of a root node, left Binary_Tree,
and right Binary_Tree.
functions:
for all bt, bt1, bt2  BinTree, item  element
Bintree Create( )::= creates an empty binary tree
Boolean IsEmpty(bt)::= if (bt==empty binary
tree) return TRUE else return FALSE
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Abstract Data Type Binary_Tree (2/2)
BinTree MakeBT(bt1, item, bt2)::= return a binary tree
whose left subtree is bt1, whose right subtree is bt2,
and whose root node contains the data item
Bintree Lchild(bt)::= if (IsEmpty(bt)) return error
else return the left subtree of bt
element Data(bt)::= if (IsEmpty(bt)) return error
else return the data in the root node of bt
Bintree Rchild(bt)::= if (IsEmpty(bt)) return error
else return the right subtree of bt
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Slide 8-79
Information Hiding Summary
 3 access control clauses for C++ class members
 private: clause for hidden entities
 public: clause for interface entities
 protected: clause - for inheritance (extension)
 friend functions or classes - to provide access to
private members in some unrelated program units
or functions
 friend functions are not member functions of class
– Defined outside of class scope
 if B a friend of A, A not necessarily a friend of B
Java 不寫 access control modifier 表示 package available
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Inheritance (繼承, 擴充) (1/3)
class Animal{
long height;
protected:
double hehe;
public:
float weight;
void jump( ) { /** … **/ }
};
class Mankind : public Animal {
long iq;
public:
void jump( ) { /** override **/ }
void talk( ) { /** new **/ }
};
In C++, ";" is required to terminate a class
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int main( ) {
Animal x;
Mankind y;
x.jump( );
cout << sizeof(x)<<endl;
cout << sizeof(y)<<endl;
y.jump( );
y.talk( );
}
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81
Slide 8-81
Inheritance (2/3)
 Inheritance lets us create new classes from existing classes
 Single inheritance: New class derived from one base class
 Multiple inheritance: New class derived from more than
one base class (may cause problems)
 General syntax to define a derived class:
Class className: memberAccessSpecifier baseClassName
{
// member list …
}
 memberAccessSpecifier can be public, protected and
private
 If no memberAccessSpecifier, it is a private inheritance
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Inheritance (3/3)
Protected Members of a Class
 The protected members of a class can be accessed by not
only the other members inside the class, but also the
members in its derived classes
 The protected members cannot be accessed outside the class
 If memberAccessSpecifier is public, all the members of the
base class keep their access rights in the derived class
 If memberAccessSpecifier is protected, the public members
of the base class become protected in the derived class, but
the protected and private keep no change
 If memberAccessSpecifier is private, all the members of the
base class become private in the derived class
若沒有繼承, 則寫 protected 與 private 完全相同
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83
Slide 8-83
How can two classes be related?
Inherits, Contains, TalksTo
• Generalization-specialization or IsA
– NamedBox IsA Box
– Diagram: Triangle on the relationship line
• Association or HasA
– Box HasA Pen
– Diagram: Just a relationship line
– Aggregation is a part-whole relationship
• Diagram: Diamond on the line
• Dependency or TalksTo
– Dependency is sort of temporary HasA
• Diagram: Dashed line in UML (後面談到)
– Example: A has a method that returns a B
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Slide 8-84
Mankind inherits Animal (C++)
Classes can
be in same
file
class Animal {
int height = 0;
int weight = 0;
public:
void talk( )
{ printf("Won");}
};
public 繼承
class Mankind :public Animal {
private: int iq = 120;
public: void talk( ) { printf("Hello");}
};
/* 分號不能省掉 */
In C++, ";" is required to terminate a class
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Slide 8-85
manlib.h
#ifndef __MANLIB__
#define __MANLIB__
class animal { // 建議大寫開頭: class Animal {
int pv1;
float pv2;
protected:
int pt1[5];
public:
animal(int = 38); // default parameter
float pb1;
int pb2[9];
void talk(void);
};
class Mankind:public animal {
char * pv3;
public:
Mankind(char * ="NoName");
// Constructor with default 參數
~Mankind( );
// Destructor
int pb3[8];
void talk(void);
};
#endif
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Slide 8-86
manlib.cpp (1/2)
// Implementation file for "animal" and "Mankind"
#include <stdio.h>
#include <iostream>
//#include <iostream.h> // 舊的C++ 用 iostream.h
using namespace std; // 舊的C++不能用 namespace
#include "manlib.h"
animal::animal(int x) { // constructor
pv1=x;
pv2=45.67;
this->pb1=135.246;
for (int i=0; i<9; i++) pb2[i]=i+1;
//pb2={ 1,2,3,4,5,6,7 ,8,9};
cout<<" Animal shows up\n";
};
void animal::talk(void)
{
cout << " animal talk, pv1=" << dec <<pv1 <<"=0x" << hex << pv1 <<"\n";
cout << " \t pv2=" << pv2 <<"\n";
cout << " \t pb1=" << pb1 <<"\n";
cout << " \t pb2[6]=" << pb2[6] <<"\n";
};
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Slide 8-87
manlib.cpp (2/2)
Mankind::Mankind(char * name){
pv3=name;
cout << " Mankind "<< pv3 << " appears\n";
}
Mankind::~Mankind(void){
cout << " %%% Mankind "<< this->pv3 << " is dying \n";}
void Mankind::talk(void)
{
// cout << " Mankind talk, pv1=" << pv1 <<"\n";
// cout << " Mankind talk, pb2=" << pb2 <<"\n";
// cout << " Mankind talk, pb2=" << animal::pb2 <<"\n";
cout << " Mankind talk, pb2[0]=" << pb2[0] <<"\n";
cout << " Mankind talk, pv3=" << pv3 <<"\n";
cout << " Mankind talk, pb3[3]=" << pb3[3] <<"\n";
};
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Slide 8-88
Using Mankind 與 animal (mannew.cpp)
#include <stdio.h>
#include <iostream> // 注意
// 舊的C++不能用
// #include <iostream.h>
#define call
#include "manlib.h"
using namespace std;
animal aa1(123), aa2(456);
Mankind * mm1, *mm2;
void onlyasub(void)
{ Mankind nobody;
cout << " Now in routine onlyasub\n";
}
main( ) {
aa1.talk();
cout << "Welcome to C++\n";
call onlyasub();
mm1= new Mankind("Chang-3");
mm2= new Mankind("Lee-4");
cout << "mm1->pb1= " << mm1->pb1
<< endl;
cout << " (Let mm1 talk)\n";
mm1->talk( );
delete mm2;
cout << " (and then Let mm1 talk"
<< " by animal method)\n";
mm1->animal::talk( );
return(0);
}
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Slide 8-89
Using Mankind 與 animal (mannew.cpp)
#include <stdio.h>
#include <iostream> // #include <iostream.h>
#define call
#include "manlib.h"
using namespace std; // with 新寫法
animal aa1(123), aa2(456);
Mankind * mm1, *mm2;
void onlyasub(void)
{ Mankind nobody;
cout << " Now in routine onlyasub\n";
}
main(){
aa1.talk();
cout << "Welcome to C++\n";
call onlyasub();
mm1= new Mankind("Chang-3");
mm2= new Mankind("Lee-4");
cout << "mm1->pb1=" << mm1->pb1 << "\n";
cout << " (Let mm1 talk)\n";
mm1->talk( );
delete mm2;
cout << " (and then Let mm1 talk by animal method)\n";
mm1->animal::talk( );
return(0);
Copyright
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Slide 8-90
Test class Mankind and animal
g++ -c manlib.cpp
g++ mannew.cpp manlib.o
./a.out
Animal shows up
Animal shows up
animal talk, pv1=123=0x7b
pv2=45.67
pb1=135.246
pb2[6]=7
Welcome to C++
Animal shows up
Mankind NoName appears
Now in routine onlyasub
%%% Mankind NoName is dying
Animal shows up
Mankind Chang-3 appears
Animal shows up
Mankind Lee-4 appears
mm1->pb1=135.246
注意比對 running result
與 程式碼!
(Let mm1 talk)
Mankind talk, pb2[0]=1
Mankind talk, pv3=Chang-3
Mankind talk, pb3[3]=0
%%% Mankind Lee-4 is dying
(and then Let mm1 talk by animal method)
animal talk, pv1=38=0x26
pv2=45.67
pb1=135.246
pb2[6]=7
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Slide 8-91
問題與思考: inherit == extend
class 豪華鬧鐘 : public 鬧鐘 {
// …豪華鬧鐘 is_a 鬧鐘
};
class Stack : private Deque {
// …
};
class Stack {
Deque x; // …
};
class Stack : public Vector {
// …
};
class Stack {
Vector x; // …
};
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Slide 8-92
Mankind extends Animal (Java)
Should be
in different
files
public class Animal {
private int height = 0;
private int weight = 0;
public void talk( )
{ System.out.println(“Arhh");}
}
public class Mankind extends Animal {
private int iq = 120;
public void talk( )
{ System.out.println("Hello");}
}
不
要
管
文
法
Mankind is-a Animal
One Java file can only have one public class
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Slide 8-93
Upcasting and Polymorphism
 Upcasting:
Taking an object reference and treating it as a reference to its
base type is called upcasting, because of the way inheritance
trees are drawn with the base class at the top.
.•沒有 upcasting 就沒有所謂的Polymorphism(多型)
•Base class 的指標(C++)可以指向 derived class 的 object
•Base class 的參考(reference, in Java) 可以參考到derived
class 的 object
•Example: 牛肉麵, 豬肉麵, 羊肉麵 --- 都是麵 (upcasting)
麵 * p = new 牛肉麵( ); ( Java 則不可寫 * )
Polymorphism ensures that the appropriate method is called for an object
of a specific type when the object is disguised as a more generic type
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Slide 8-94
Polymorphism (多型) in C++
 Suppose p is a pointer which points to an object
 class Circle and Line both inherit from Shape.
 All classes have their own draw( ) functions.
Shape * p;
/* the draw( ) in Shape is virtual or not ? */
.
p = new Circle( );
P->draw( );
/* which draw( ) will be executed ? */
p = new Line( );
P->draw( );
/* which draw( ) will be executed ? */
 If draw( ) is virtual, P->draw( );will run the correct draw( )
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Slide 8-95
Polymorphism (多型) in Java
 Suppose p is an Object of Shape which is actually a “reference”
 class Circle and Line both inherit from Shape.
 All classes have their own draw( ) functions.
Shape p;
// the draw( ) in Shape is virtual or not ?
.
p = new Circle( );
P.draw( );
// which draw( ) will be executed ?
p = new Line( );
P.draw( );
// which draw( ) will be executed ?
 In Java, all functions are automically virtual, except final one
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Polymorphism, C++ example (1/2)
// polymo.cpp -- CopyWrong by [email protected]
#include <iostream.h>
class Shape{
public:
virtual
// 把這列去掉再 run 看看, 去掉就沒 polymorphism
void draw( ) { cout << "drawing\n"; }
};
class Line: public Shape{
public:
void draw( ) { cout << "draw a line\n"; }
};
class Circle: public Shape{
public:
void draw( ) { cout << "here is a circle\n"; }
};
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Slide 8-97
Polymorphism, C++ example (2/2)
int main( ) {
Circle * ppp;
Shape * fig[9]; // base class的指標可指向衍生出的object
// ppp = new Shape( ); // error!
ppp = (Circle *)new Shape( );
/* cast */
ppp -> draw( );
ppp = (Circle *)new Line( );
ppp -> draw( );
ppp = new Circle( );
ppp -> draw( );
cout << "======" << endl;
fig[0] = new Line( );
fig[1] = new Circle( );
fig[2] = new Circle( );
fig[3] = new Line( ); fig[4] = new Circle( );
for(int k=0; k<5; k++){
fig[k] -> draw( );
}
}
98
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Slide 8-98
Polymorphism:用 Base class 的pointer (C++) 或
是 reference (Java)去操作derived class 的物件
class Shape{
public:
virtual void draw( ) = 0; // pure virtual function
}; // Abstract class because it contains at least one pure virtual function
class Circle: public Shape { // Circle is a Shape
void draw( ) { } // must implement this
};
Class Line: public Shape { void draw( ) { /*…*/ } }; // Line is a Shape
Shape * p;
p = new Shape( ); // Wrong ! 因為 Shape 為 ABC (Abstract Base Class)
p = new Circle( ); // OK, good!
P-> draw( ); // will run Circle::draw( )
P = new Line( ); p-> draw( );
// 用 Line 的 draw( )
Java的 Abstract class 必須用 abstract 開頭!
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Slide 8-99
Why virtual function?
• Virtual function to achieve Polymorphism
– Dynamic binding : Shape * p;
p-> draw( ); //被譯為執行 p 指過去的object所屬的
class之 draw( ) 函數. 該object有包括一指標會指到正
確的函數 (在 object 被 new 出之時才填入的, 例 p=
new Circle( ); 時會填指標指向Circle( ) 的 draw() function )
• What if not virtual?
Polymorphism (多型)!
– Static binding 較有效率, 但可能錯 : 假設 draw( )不是 virtual
Shape * p;
p-> draw( ); //一定被譯為執行 Shape::draw( );
C++class 的 function 程式人員可決定是否 virtual
Java 的 functions 永遠自動 virtual, except final functions
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ABC (Abstract Base Class)
• Abstract Base Class (抽象基底類別)
– Base Class ? Derived class ? Super class ?
– Abstract Class?
• Class that contains pure virtual function (abstract function)
• Virtual function?
• Pure Virtual function?
– virtual void haha( long para) = 0;
– Abstract class 不可以用來生出 Object
– 專為 polymorphism 而設的class, 提供其子孫有共同
一致的 interface 或說一致的 API
C++ 的 pure virtual function 就是Java的 abstract function!
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Polymorphism vs. Function name overloading
• Function name overloading is implemented using
a technique that change the function name to
include types of all parameters.
• Polymorphism is implemented using a technique
called late (or dynamic) method binding: which
exact method to call is determined at run time.
Write a small C/C++ program and then have compiler to
translate it into assembly source code:
gcc -S file.c
g++ -S file.cpp
tcc -S file.c
tcc -S file.cpp
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C++ How to …overloading/polymorphism
 C++ 到底是用了什麼技術辦到 function name overloading ? 事實上
只是用了一個超級簡單的 idea:
– C++只是把參數的型別納入函數名稱中而已, Compiler會偷換
function name, 參數的type也變成 function_name 的一部份: (
static binding)
例如: void swap(int&, int&); 會被譯為(可能!):
__swap_F2RiRi
 如何達成 polymorphism ? (C++ 要用到指標才有多型)
 透過 virtual function  dynamic binding
 p-> draw( ); 譯成去執行 p 指過去之物件內有個指標指
過去的函數表中draw的項目位置指過去的那個函數! (相關
指標在 new 出物件時填入)
若 draw( ) 不是 virtual, 則 p-> draw( ); 會採用 static binding 方式
翻譯, 即依據宣告看p是啥的指標直接譯出要執行哪個 function
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問題與思考 (Why??)
•現在用 class 製作軟體零件(元件), 雖可以
有許多個 long 的 Stack
•若要一個 long 的 Stack 以及一個 double
的 Stack 呢?
甚至一個 Student 的 Stack 呢?
• ? Copy 來改並換 class 名稱嗎? NO!
Solution ==> using C++ template Class
(樣版類別) (Generic type;汎用型別)
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C++ Template (樣版);
JDK1.5 以後有 Generic class type
• Templates provide direct support for generic
programming
– The C++ template mechanism allows a type to be a
parameter in the definition of a class or a function
– definer specifies the container class in terms of that
argument
– users specify what the type of contained objects is
• The template implementation is a mechanism that
generates types when needed based on the user’s
specification (compiler 幫忙copy去改 )
• Every major standard library abstraction is
represented as a template (eg., C++ STL)
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Generic data type -- Template class
• 如何有多個可處理不同 data type的堆疊?
template <class T>
class Stack {
T data[99];
int sptr;
public :
Stack( );
void push(T x);
T top(void);
void pop(void);
template declaration,
T is type argument
T is uesd exactly like
other type names
Stack<int> xo;
不該改的不要改, 例
如 int sptr; 當然不改
int empty( ) ;
// . . .
Stack<double> brandy;
Stack<Student> haha;
};
Stack<T>::Stack( ) { sptr = -1; }
/* … */
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Class name is used
exactly like others
But you have to specify
the type in < >
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/* … */
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Template function (Generic function)
• C++:
template<class T, class T2> int myFun(T pa, T2 pb) {
/* … */
}
• Java:
<T, T2> int myFun(T pa, T2 pb) {
/* … */
}
107
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Object Oriented Concepts
• There are many OO tools for Software Engineering
(軟體工程)
• OOA (Language Independent)
– CRC cards (Class-Responsibility-Collaborator) by Ward
Cunningham and Beck
• OOD
– Class diagram, UML, Rational ROSE, …
• OOP
– Languages support OOP: C++, Java, Ada, …
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OOA: CRC Cards
• Step one: Write down all the objects that relate
(Focus on the nouns because objects are nouns)
• Step two: Write CRC cards and work through
scenarios
– Class-Responsibility-Collaborator Cards (Cunningham
and Beck)
– Just 3x5 cards
•Although CRC is not part
of UML, they add some
very useful insights
throughout a development.
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Data fields (attributes) 寫在背面
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OOD: Object-Oriented Design, How?
• Step one: Create a UML class diagram of
your objects
• Step two: Create a detailed description of
the services to be performed
– Peter Coad's "I am a Count. I know how to
increment…"
– Activity, sequence, or collaboration UML
diagrams
UML == “Unified Modeling Language”
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OO Design is an Art
• Object Oriented is a solution to Large software system
• Designing a good OOP application is a daunting task.
• It is largely an art: there are no precise rules for identifying
classes, objects, and methods.
• Many considerations determine which classes should be
defined and their responsibilities.
• A bad design can nullify all the potential OOP benefits.
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Tips to find/determine classes
• A few considerations that determine which classes
are defined and their responsibilities:
–
–
–
–
–
–
Manageable size
Clear limited functionality
Potential reuse
Support for multiple objects
The need to derive from a library class
The need to make a listener or to implement a particular
interface
– The need to collect a few data elements in one entity
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Façade Design Pattern
• Façade: defines a clean, high-level interface to a subsystem.
• Context: building easy-to-use and maintain subsystems
• Problem: Each class in the subsystem provides part of the subsystem’s
functionality, clients has to know the inside, changes to the subsystem may
require changes to the clients.
• Solution: Add an interface class (the façade class) that knows the structure of
the subsystem and forwards requests…
• Consequences: no or less dependency of client from structure of subsystem,
ideal for layered subsystems
Facade
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MDA-Model Driven Architecture?
• A New Way to Specify and Build Systems
– 2001年由OMG制定的新開發架構 (http://www.omg.org)
– 以UML Model(塑模)為基礎
– 支援完整開發週期: Analysis, Design, Implementation,
Deployment, Maintenance, Evolution & Integration with
later systems (改進與後續整合)
– 內建協同運作性及跨平台性
– 降低開發初期成本及提高ROI (投資報酬)
– 可套用至你所使用的任何環境:
• Programming language
 Network
• Operating System
 Middleware
ROI : Return On Invest
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Unified Modeling Language
http://www.omg.org
http://www.UML.org
• There have been O-O gurus for many years
• Three of them worked together to define UML (“Three
amigos”: Booch, Rumbaugh, Jacobson)
• Not so much a language, but more a process for designing
software
• Has now been approved as a standard by the Object
Management Group (OMG)
• Very powerful, many forms of notation
– It's even provable! (with OCL)
amigos = friends
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(Object Constrain Language)
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So, What is UML?
軟體工程師共通的語言
• UML is a Unified Modeling Language
• UML is a set of notations, not a single methodology
• Modeling is a way of thinking about the problems using
models organized around the real world ideas.
• Resulted from the convergence of notations from three
leading Object-Oriented methods:
• Booch method (by Grady Booch)
• OMT (by James Rumbaugh)
• OOSE (by Ivar Jacobson)
• You can model 80% of most problems by using about 20%
of the UML
UML is a “blueprint” for building complex software
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History of the UML( http://www.uml.org/ )
Public
Feedback
Approved 2004
UML 2.0
Minor revision 2003
UML 1.5
Minor revision 2001
UML 1.4
Minor revision 1999
UML 1.3
OMG Acceptance, Nov 1997
Final submission to OMG, Sept 1997
First submission to OMG, Jan 1997
UML 1.1
UML partners
UML 1.0
Web - June 1996
UML 0.9
OOPSLA 95
Unified Method 0.8
Other methods
OOSE Booch method
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OMT
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UML 常用的 Diagrams (目前共有12種)
• Use case diagrams
– Functional behavior of the system as seen by the user.
• Class diagrams
– Static structure of the system: Objects, Attributes, and
Associations.
• Activity diagrams
– Dynamic behavior of a system, in particular the workflow, i.e. a
flowchart.
• Sequence diagrams
– Dynamic behavior between actors and system objects.
• Statechart diagrams
– Dynamic behavior of an individual object as FSM (有限狀態機).
UML is a modeling language that only specifies semantics and notation
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UML 12 Diagrams
• Structural:
• Behavior :
– Use Case
– Sequence
– Collaboration
– State Chart
– Activity
– Class
– Component
– Deployment
– Object
• Model Management:
– Packages (class diagram contains packages)
– Subsystems (class diagram contains subsystems)
– Models (class diagram contains models)
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UML Core Conventions
• Rectangles are classes or instances
• Ovals are functions or use cases
• Types are denoted with non-underlined names
 SimpleWatch
 Firefighter
• Instances are denoted with an underlined names
 myWatch:SimpleWatch
 Joe:Firefighter
• Diagrams are higraphs
Higraphs are an
extension to the
familiar Directed
Graph structure
where nodes are
connected by
edges to other
nodes. Nodes
represent entities
in some domain (in
our case, classes,
packages, methods,
etc.).
– Nodes are entities (e.g. classes, states)
– Arcs are relationships among entities (e.g. sender/receiver)
– Containment represents belonging (e.g. use cases in package)
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Use Case Diagram examples
Package
SimpleWatch
Actor
A use case documents the
interaction between the system
user and the system. It is highly
detailed in describing what is
required but is free of most
implementation details and
constraints.
ReadTime
WatchUser
Use case
SetTime
WatchRepairPerson
ChangeBattery
Use case diagrams represent the functionality of the system
from user’s point of view. (強調 what, 但暫不管 how)
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Class Diagram : a simple Watch
Class
Multiplicity
Association
SimpleWatch
1
2
PushButton
state
push()
release()
1
1
1
1
2
LCDDisplay
blinkIdx
blinkSeconds()
blinkMinutes()
blinkHours()
stopBlinking()
referesh()
Attributes
Battery
load()
1
Time
now()
Operations
Class diagrams represent the structure of the domain or system
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Sequence Diagram
Object
:WatchUser
:SimpleWatch
pressButton1(
)
pressButton1()
:LCDDisplay
:Time
blinkHours()
blinkMinutes()
pressButton2()
incrementMinutes()
refresh()
pressButtons1And2()
Activation
commitNewTime()
stopBlinking()
Activation
Message
Sequence diagrams represent the behavior as interactions
It shows sequence of events for a particular use case
• A Sequence diagram shows the explicit sequence of
messages suitable for modeling a real-time system,
whereas a collaboration diagram (next slide) shows
the relationships between objects.
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Collaboration Diagram
• A collaboration diagram and sequence diagram conveys similar
information but expressed in different ways.
• A collaboration shows the relationships among objects
• Describes the set of interactions between classes or types
Object diagram with
numbered messages
Sequence numbers of messages
are nested by procedure call
124
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State chart Diagrams for the watch
Event
Initial state
button1&2Pressed
Increment
Hours
button1Pressed
Transition
button1&2Pressed
button2Pressed
Blink
Hours
State
Blink
Minutes
button2Pressed
Increment
Minutes
button1Pressed
button1&2Pressed
Blink
Seconds
Stop
Blinking
Final state
button2Pressed
Increment
Seconds
FSM: Finite State Machine
125
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Activity Diagrams
• An activity diagram shows flow control within a system
Handle
Incident
Document
Incident
Archive
Incident
• An activity diagram is a special case of a state chart diagram
in which states are activities (“functions”)
• Two types of states:
– Action state:
• Cannot be decomposed any further
• Happens “instantaneously” with respect to the level of abstraction used in
the model
– Activity state:
• Can be decomposed further
• The activity is modeled by another activity diagram
描述Business process或use case的操作流程; 像流程圖
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Classes in UML
• Classes describe objects
– Behaviour (member function signature / implementation)
– Properties (attributes and associations)
– Association, aggregation, dependency, and inheritance
relationships
– Multiplicity and navigation indicators
– Role names
• Objects described by classes collaborate
– Class relations → object relations
– Dependencies between classes
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Visibility shown as
+
public
private
#
protected
UML Class
Class name
Data members
(attributes)
Instance methods
Class method (static)
Return types
Arguments
Data members, arguments and methods are specified by
visibility name : type
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Class Attributes
Attributes are the instance data members
and class data members
Class data members (underlined)
are shared between all instances
(objects) of a given class
Class name
Attribute
compartment
Data types shown after ":"
Visibility shown as
+
public
private
#
protected
visibility name : type
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Class Operations (Interface)
Operations are the class
methods with their argument
and return types
Public (+) operations define the
class interface
Class methods (underlined)
can only access to class data
members, no need for a class
instance (object)
Operations
compartment
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Template Classes
Type parameter(s)
Operations compartment
as usual, but may have
type parameter instead of
concrete type
Generic classes depending on parametrised types
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Class Inheritance
Base class or super class
Arrow shows direction
of dependency (B inherits A)
Derived class or subclass
→
→
→
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B inherits A's interface,
behaviour and data members
B can extend A, i.e. add new
data members or member functions
B depends on A,
A knows nothing about B
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Multiple Inheritance (Java)
The derived class inherits
interface, behaviour and
data members of all its
base classes
implements
Extension and overriding
works as before
extends
B implements the interface A and
is also a "countable" class since it
inherits class Countable
class B extends Countable implements A { /*…*/ }
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Class Friendship
Java has NO friend
Friends are granted access to private data members and
member functions
Friendship is given to other classes, never taken
Friendship breaks data hiding, use carefully !
Friend is the only one who can touch your private!
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Java has NO friend
• Java does not have the friend keyword from C++.
• However, there is a way to emulate that. Please see these:
– http://macchiato.com/columns/Durable7.html
– http://www.langer.camelot.de/Publications.htm
• Friend function or member function?
– If the first parameter is NOT an object of the current class,
you have to write it as a friend function so that it can
access the private members
– If the first parameter is an object of the current class, then
you can write it as a member function and/or as a friend
function
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Recommended Book:
UML Distilled
• UML Distilled by Martin Fowler is a great
practical introduction to UML
– Official UML book series published by AddisonWesley
– Serious O-O designers DO use UML
http://www.omg.org
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UML Tools
• Most complete tool: Rational Rose,
http://www.rational.com
• Lots of others :
– Together by Object International,
– Borland Together 2006 http://www.togethersoft.com
– BOOST (Basic Object-Oriented Support Tool) by
Noel Rappin, available on CD/CoWeb
– Argo-UML, ObjectPlant, Posiden, etc.
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Thank You!
Data
Abstraction
謝謝捧場
[email protected]
蔡文能
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