Propedéutico de Programación

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1 Propedéutico de Programación Coordinación de Ciencias Computacionales Semana 4, Tercera Parte Dra. Pilar Gómez Gil Versión

2 Capítulo 5 ADT s para Pilas y Colas

3 Stacks of Boxes and Books TOP OF THE STACK TOP OF THE STACK

4 Stacks Stack An abstract data type in which elements are added and removed from only one end (LIFO)

5 Stacks Transformers Push Pop change state Observers IsEmpty IsFull Top observe state What about an iterator?

6 Stacks class StackType { public: StackType(); bool IsEmpty() const; bool IsFull() const; void Push(ItemType item); void Pop(); ItemType Top() const; Logical Level

7 Linked Implementation private: } NodeType* topptr; Can we borrow code from UnsortedType for Push and Pop?

8 Linked Implementation void StackType::Push(ItemType newitem) { } if (IsFull()) throw FullStack(); else { NodeType* location; location = new NodeType; location->info = newitem; location>next = topptr; topptr = location; }

9 Linked Implementation void StackType::Pop() { if (IsEmpty()) throw EmptyStack(); else { NodeType* tempptr; tempptr = topptr; topptr = topptr->next; delete tempptr; } } Does this work for stacks of one item? More than one item?

10 Linked Implementation More than one item

11 Linked Implementation One item

12 Linked Implementation What about the constructor, destructor, and observer functions? We can borrow all but Top from class UnsortedType ItemType StackType::Top() { if (IsEmpty()) throw EmptyStack else return topptr->info; }

13 Ver los programas en stack.zip

14 Queues

15 Queues

16 Queues Queue An abstract data type in which elements are added to the rear and removed from the front; a first in, first out (FIFO) structure

17 Queues Transformers MakeEmpty Enqueue Dequeue change state Observers IsEmpty IsFull observe state What about an iterator? 17

18 Queues class QueType { public: QueType(int max); QueType(); ~QueType(); bool IsEmpty() const; bool IsFull() const; void Enqueue(ItemType item); void Dequeue(ItemType& item); Logical Level

19 Linked Implementation Data structure for linked queue

20 Linked Implementation Enqueue(newItem) Set newnode to the address of newly allocated node Set Info(newNode) to newitem Set Next(newNode) to NULL Set Next(rear) to newnode If queue is empty Set front to newnode else Set Next(rear) to newnode

21 Linked Implementation Dequeue(item) Set tempptr to front Set item to Info(front) Set front to Next(front) if queue is now empty Set rear to NULL Deallocate Node(tempPtr)

22 Ver programas en queue.zip

23 Chapter 6 Lists Plus 23

24 Circular Linked Lists Circular linked list A list in which each node has a successor; the last element is succeeded by the first element

25 Circular Linked List Why is it better to have the external pointer point to the last element?

26 Circular Linked List Initialization for search

27 Circular Linked List FindItem cases

28 Circular Linked List Insert an item

29 Circular Linked List Delete an Item

30 Doubly Linked List Doubly linked list A is in which each node is linked to both its successor and its predecessor 30

31 Doubly Linked List Insert an item 31

32 Doubly Linked List Does it matter in which order we change the pointers?

33 Doubly Linked List Delete an item

34 Copy Structures In a linked structure, the external pointer is enclosed within the stack object, but the linked structure to which it points is not What causes this problem?

35 Copy Structures Shallow copy An operation that copies one class object to another without copying pointed-to data Deep copy An operation that not only copies one class object to another but also makes copies of any pointed-to data See the difference?

36 Copy Structures

37 Copy Structures In summary A shallow copy shares the pointed to data with the original class object A deep copy stores its own copy of the pointed to data at different locations than the data in the original class object How do we make a deep copy? 37

38 Copy constructor Copy Structures A special member function of a class that is implicitly invoked when passing a parameter by value, initializing a variable in a declaration, and returning an object as the value of function StackType(const StackType& anotherstack); Of course, the code should implement a deep copy!

39 Copy Structures That about the assignment operator? The assignment operator does a shallow copy! We can overload the assignment operator class StackType { public:... void operator=(stacktype); private:... void StackType::operator=(StackType anotherstack) } // code for a deep copy Can we overload other operators? 39

40 Copy Structrres Al relational operators can be overloaded bool operator<(itemtype other) const; // Returns true if self is less than other bool operator>(itemtype other) const; // Returns true if self is greater than other bool operator==(itemtype other) const; // Returns true if self is equal to other... Of course, you must write the code as for any other function

41 Polymorphism Polymorphism The ability to determine which of several operations with the same name to apply to a particular object; a combination of static and dynamic binding Binding The time at which a name or symbol is bound to the appropriate static binding: bound at compile time dynamic binding: bound at run time

42 Polymorphism NewItemType is derived from ItemType void PrintResult(ItemType& first, ItemType& second); How can this be?

43 Polymorphism C++ relaxes scope rules to allow dynamic binding The type of the actual parameter may be an object of a derived class of the formal parameter virtual void PrintResult(ItemType& first, ItemType& second); Word virtual in base class (ItemType), definition forces dynamic binding Note: Parameters must be reference

44 C++ Tips 1. Operators ::. sizeof, and?: may not be overloaded 2. At least one operand must be a class instance 3. Precedence, operator symbols, or number of operands cannot be changed 4. Overloading ++ and -- requires prefix form use by client 5. To overload these operators = ( ) [ ], member functions must be used 6. An operator can be given multiple meanings if the data types of operands differ 44

ADTs Stack and Queue. Outline

ADTs Stack and Queue. Outline Chapter 5 ADTs Stack and Queue Fall 2017 Yanjun Li CS2200 1 Outline Stack Array-based Implementation Linked Implementation Queue Array-based Implementation Linked Implementation Comparison Fall 2017 Yanjun