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Shifting blocks of elements…Model of a list object…Sample listThe list ADTCLASS list ConstructorsCLASS list Operations (7 slides)CLASS list::iterator OperationsInserting an element into a listRemoving an element from a listOrdered listsSplicing two listsSummary Slides (5 slides)

Chapter 6 Chapter 6 – – The List Container and IteratorsThe List Container and Iterators

2 Main IndexMain Index ContentsContents

Shifting blocks of elements to Shifting blocks of elements to insert or delete a vector iteminsert or delete a vector item

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Model of a list object with links Model of a list object with links to next and previous elementto next and previous element

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Sample listSample list

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G o n zales ( 5 )

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The List ADTThe List ADT The list API documents the member function

prototype as well as pre- and postconditions.– provides three constructors to declare a list object.

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CLASS list Constructors <list>

list();Create an empty list. This is the default constructor.

list(int n, const T&value = T());Create a list with n elements, each having a specified value. If the value argument is omitted, the elements

are filled with the default value for type T. Type T must have a default constructor, and the default value of type T is specified by the notation T().

list(T *first, T *last);Initialize the list, using the address range [first, last).


CLASS list Operations <list>

T& back();Return the value of the item at the rear of the list. Precondition: The vector must contain at least one

element.

bool empty() const;Return true if the vector is empty, false otherwise.

T& front();Return the value of the item at the front of the list. Precondition: The vector must contain at least one

element.



void push_back(const T& value);Add a value at the rear of the list. Postcondition: The list has a new element at the

rear, and its size increases by 1.

void pop_back();Remove the item at the rear of the list. Precondition: The list is not empty. Postcondition: The list has a new element at the rear

or is empty.



void push_front(const T& value);Add a value at the front of the list. Postcondition: The list has a new element at the

front, and its size increases by 1.

void pop_front();Remove the item at the front of the list. Precondition: The list is not empty. Postcondition: The list has a new element at the front

or is empty.

int size() const;Return the number of elements in the vector.



iterator begin();Returns an iterator that references the first position

(front) of the list. If the list is empty, the iterator value end() is returned.

const_iterator begin();Returns a const_iterator that points to the first position (front) of a constant list. If the list is empty, the

const_iterator value end() is returned.

iterator end();Returns an iterator that signifies a location immediately out of the range of actual elements. A program must

not dereference the value of end() with the * operator.



iterator end();Returns an iterator that signifies a location immediately out of the range of actual elements. A program must

not dereference the value of end() with the * operator.

const_iterator end();Returns a const_iterator that signifies a location

immediately out of the range of actual elements in a constant list. A program must not dereference the value of end() with the * operator.



void erase(iterator pos);Erase the element pointed to by pos.Precondition: The list is not empty.Postcondition: The list has one fewer element.

void erase(iterator first, iterator last);Erase all list elements within the iterator range [first,

last].Precondition: The list is not empty.Postcondition: The size of the list decreases by the

number of elements in the range.



iterator insert(iterator pos, const T& value);Insert value before pos, and return an iterator pointing to the position of the new value in the list. The

operation does not affect any existing iterators.Postcondition: The list has a new element.


CLASS list::iterator Operations <list>

*:Accesses the value of the item currently pointed to by the iterator.

*iter;*iter;

++: Moves the iterator to the next item in the list. iter++;iter++;

--: Moves the iterator to the previous item in the list.

iter--;iter--;

==: Takes two iterators as operands and returns truewhen they both point at the same item in the list.

iter1 == iter2iter1 == iter2

!=: Returns true when the two iterators do not point at the same item in the list.

iter1 != iter2iter1 != iter2


Inserting an element into a listInserting an element into a list

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Removing an element from a listRemoving an element from a list

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Ordered listsOrdered lists8 27 46 0

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Position the iterator curr at the front of the list.

Insert 50 in the list:


Splicing two listsSplicing two lists

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Summary Slide 1Summary Slide 1

§- list - A Sequence of elements stored by position.

- Index access is not available…§- to access the value of an element, must pass

through its preceding elements.

§- list iterator- A generalized pointer that moves through a list

element by element… forward or backward

- At any point, the * operator accesses the value of a list item.



§- The list class has two iterator types:1)1) iteratoriterator:

A generalized list traversal pointer.

2)2) constconst __ iteratoriterator:

must be used with a constant list object. Each type is a nested class of list and must be

accessed by using the scope operator ::::



§- the list member function begin()- Gives an iterator an initial value that points to the

first element.

§- the list member function end()- Returns an iterator pointing just past the last

element of the list.



§- The sequential search of a list object- implemented by using an iterator range

[firstfirst, lastlast).

- It returns an iterator that points at the target value or has value lastlast if the target is not in the list.



§- list class member fns insert() and erase()

- Both use an iterator argument to modify a list.

1)1) insert()insert(): places value in the list before the data

referenced by the iterator pospos.

2)2) erase()erase():removes the data item referenced by pospos from the list.

main index contents 11 main index contents shifting blocks of elements… shifting blocks of...

Documents

list elements

constant list

list api

list container

list decreases

iterator operations

sample list slide

list object model