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![Page 1: Chapter 5 introduces the often- used data structure of linked lists. This presentation shows how to implement the most common operations on linked lists.](https://reader033.fdocuments.us/reader033/viewer/2022042601/5518d00555034638098b4ff6/html5/thumbnails/1.jpg)
Chapter 5 introduces the often-used data structure of linked lists.
This presentation shows how to implement the most common operations on linked lists.
Linked Lists in Action
CHAPTER 5Data Structures and Other Objects
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For this presentation, nodes in a linked list are objects, as shown here.
data_field
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class node{public: typedef double value_type; ...private value_type data_field; node *link_field;};
Declarations for Linked Lists
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The data_field of each node is a type called value_type, defined by a typedef.
data_field
link_field
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data_field
link_field
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class node{public: typedef int value_type; ...private value_type data_field; node *link_field;};
Declarations for Linked Lists
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Each node also contains a link_field which is a pointer to another node.
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class node{public: typedef int value_type; ...private value_type data_field; node *link_field;};
Declarations for Linked Lists
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Declarations for Linked Lists
A program can keep track of the front node by using a pointer variable such as head_ptr in this example.
Notice that head_ptr is not a node -- it is a pointer to a node.
head_ptr
data_field
link_field
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Declarations for Linked Lists
A program can keep track of the front node by using a pointer variable such as head_ptr.
Notice that head_ptr is not a node -- it is a pointer to a node.
We represent the empty list by storing null in the head pointer.
head_ptr
null
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void list_head_insert(node*& head_ptr, const node::value_type& entry);
Inserting a Node at the Front
We want to add a new entry, 13, We want to add a new entry, 13, to the to the frontfront of the linked list of the linked list shown here.shown here.
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entry
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Inserting a Node at the Front
Create a new node, pointed to by a local variable insert_ptr.
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nullhead_ptr
entry
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insert_ptr
void list_head_insert(node*& head_ptr, const node::value_type& entry);
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Inserting a Node at the Front
insert_ptr = new node;
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entry
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insert_ptr
void list_head_insert(node*& head_ptr, const node::value_type& entry);
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Inserting a Node at the Front
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entry
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insert_ptr = new node;
Place the data in the new node's data_field.
void list_head_insert(node*& head_ptr, const node::value_type& entry);
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Inserting a Node at the Front
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nullhead_ptr
entry
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insert_ptr13
insert_ptr = new node;
Place the data in the new node's data_field.
Connect the new node to the front of the list.
void list_head_insert(node*& head_ptr, const node::value_type& entry);
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Inserting a Node at the Front
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nullhead_ptr
entry
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insert_ptr13
insert_ptr = new node(entry, head_ptr);
The correct new node The correct new node can be completely can be completely created in one step by created in one step by calling an appropriate calling an appropriate node constructor.node constructor.
void list_head_insert(node*& head_ptr, const node::value_type& entry);
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Inserting a Node at the Front
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entry
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insert_ptr = new node(entry, head_ptr);
Make the old head pointer point to the new node.
void list_head_insert(node*& head_ptr, const node::value_type& entry);
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Inserting a Node at the Front
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entry
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insert_ptr = new node(entry, head_ptr);
head_ptr = insert_ptr;
void list_head_insert(node*& head_ptr, const node::value_type& entry);
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Inserting a Node at the Front
insert_ptr = new node(entry, head_ptr);
head_ptr = insert_ptr;
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When the function returns, thelinked list has a new node at thefront.
void list_head_insert(node*& head_ptr, const node::value_type& entry);
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void list_head_insert(node*& head_ptr, const node::value_type& entry){ node *insert_ptr;
insert_ptr = new node(entry, head_ptr);
head_ptr = insert_ptr;
}
Inserting a Node at the Front
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Inserting a Node at the Front
void list_head_insert(node*& head_ptr, const node::value_type& entry){ node *insert_ptr;
insert_ptr = new node(entry, head_ptr);
head_ptr = insert_ptr;
} Does the function work
correctly for the empty list ?
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head_ptrentry
13 null
Inserting a Node at the Front
Does the function work
correctly for the empty list ?
void list_head_insert(node*& head_ptr, const node::value_type& entry){ node *insert_ptr;
insert_ptr = new node(entry, head_ptr);
head_ptr = insert_ptr;
}
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Inserting a Node at the Front
head_ptrentry
13 nullinsert_ptr
13
void list_head_insert(node*& head_ptr, const node::value_type& entry){ node *insert_ptr;
insert_ptr = new node(entry, head_ptr);
head_ptr = insert_ptr;
}
null
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Inserting a Node at the Front
head_ptrentry
13insert_ptr
13
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void list_head_insert(node*& head_ptr, const node::value_type& entry){ node *insert_ptr;
insert_ptr = new node(entry, head_ptr);
head_ptr = insert_ptr;
}
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Inserting a Node at the Front
head_ptr
13
null
void list_head_insert(node*& head_ptr, const node::value_type& entry){ node *insert_ptr;
insert_ptr = new node(entry, head_ptr);
head_ptr = insert_ptr;
}When the function
returns, the linked list has one node.
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Caution!
Always make sure that your linked list functions work correctly with an empty list.
EMPTY LIST
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Pseudocode for Inserting Nodes
Nodes are often inserted at places other than the front of a linked list.
There is a general pseudocode that you can follow for any insertion function. . .
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Pseudocode for Inserting Nodes
Determine whether the new node will be the first node in the linked list. If so, then there is only one step:
list_head_insert(head_ptr, entry);
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Pseudocode for Inserting Nodes
Determine whether the new node will be the first node in Determine whether the new node will be the first node in the linked list. If so, then there is only one step:the linked list. If so, then there is only one step:
The
func
tion
we
alre
ady
wro
te
list_head_insert(head_ptr, entry);
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Pseudocode for Inserting Nodes
Determine whether the new node will be the first node in the linked list. If so, then there is only one step:
list_head_insert(head_ptr, entry);
A pointerto the
head ofthe list
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Pseudocode for Inserting Nodes
Determine whether the new node will be the first node in the linked list. If so, then there is only one step:
list_head_insert(head_ptr, entry);
The data to put
in the new node
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Pseudocode for Inserting Nodes
Otherwise (if the new node will not be first): Start by setting a pointer named previous_ptr to point to the
node which is just before the new node's position.
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Pseudocode for Inserting Nodes
15
10
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nullhead_ptr
Otherwise (if the new node will not be first): Start by setting a pointer named previous_ptr to point to the
node which is just before the new node's position.
In this example, thenew node will bethe second node
previous_ptr
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Pseudocode for Inserting Nodes
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10
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nullhead_ptr
Otherwise (if the new node will not be first): Start by setting a pointer named previous_ptr to point to the
node which is just before the new node's position
What is the name of this orange pointer ?
Look at the pointerwhich is in the node
*previous_ptr
previous_ptr
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Pseudocode for Inserting Nodes
15
10
7
nullhead_ptr
Otherwise (if the new node will not be first): Start by setting a pointer named previous_ptr to point to the
node which is just before the new node's position
This pointer is calledprevious_ptr->link_field(although this name maybe private to the node)
What is the name of What is the name of this orange pointer ?this orange pointer ?
previous_ptr
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Pseudocode for Inserting Nodes
15
10
7
nullhead_ptr
Otherwise (if the new node will not be first): Start by setting a pointer named previous_ptr to point to the
node which is just before the new node's position
previous_ptr->link_fieldpoints to the headof a small linkedlist, with 10 and 7
previous_ptr
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Pseudocode for Inserting Nodes
15
10
7
nullhead_ptr
Otherwise (if the new node will not be first): Start by setting a pointer named previous_ptr to point to the
node which is just before the new node's position.
The new node mustbe inserted at thefront of this small
linked list.
13
Write one C++ statement which will do the insertion.
previous_ptr
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Pseudocode for Inserting Nodes
15
10
7
nullhead_ptr
Otherwise (if the new node will not be first): Start by setting a pointer named previous_ptr to point to the
node which is just before the new node's position.13
What might cause this statement to fail to compile?
previous_ptrlist_head_insert(previous_ptr->link_field, entry);
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Pseudocode for Inserting Nodes
15
10
7
nullhead_ptr
Otherwise (if the new node will not be first): Start by setting a pointer named previous_ptr to point to the
node which is just before the new node's position.13
Use a node member function to get the link field if needed.
previous_ptrlist_head_insert(previous_ptr->link( ), entry);
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Pseudocode for Inserting Nodes
Determine whether the new node will be the first node in the linked list. If so, then there is only one step:
list_head_insert(head_ptr, entry);
Otherwise (if the new node will not be first): Set a pointer named previous_ptr to point to the node
which is just before the new node's position. Make the function call:
list_head_insert(previous_ptr->link( ), entry);
![Page 37: Chapter 5 introduces the often- used data structure of linked lists. This presentation shows how to implement the most common operations on linked lists.](https://reader033.fdocuments.us/reader033/viewer/2022042601/5518d00555034638098b4ff6/html5/thumbnails/37.jpg)
Pseudocode for Inserting Nodes
The process of adding a new node in the middle The process of adding a new node in the middle of a list can also be incorporated as a separate of a list can also be incorporated as a separate function. This function is called list_insert in the function. This function is called list_insert in the linked list toolkit of Section 5.2.linked list toolkit of Section 5.2.
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Pseudocode for Removing Nodes
Nodes often need to be removed from a linked list. As with insertion, there is a technique for removing
a node from the front of a list, and a technique for removing a node from elsewhere.
We’ll look at the pseudocode for removing a node from the front of a linked list.
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Removing the Head Node
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nullhead_ptr
13
Start by setting up a temporary pointer named remove_ptr to the head node.
remove_ptr
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Removing the Head Node
10 15 7
nullhead_ptr
13
Set up remove_ptr. head_ptr = remove_ptr->link( );
remove_ptr
Draw the change that this statement will make to the linked list.
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Removing the Head Node
10 15 7
nullhead_ptr
13
Set up remove_ptr. head_ptr = remove_ptr->link( );
remove_ptr
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Removing the Head Node
Set up remove_ptr. head_ptr = remove_ptr->link( ); delete remove_ptr; // Return the node's memory to heap.
10 15 7
nullhead_ptr
13
remove_ptr
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Removing the Head Node
Here’s what the linked list looks like after the removal finishes.
10 15 7
nullhead_ptr
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It is easy to insert a node at the front of a list. The linked list toolkit also provides a function for
inserting a new node elsewhere It is easy to remove a node at the front of a list. The linked list toolkit also provides a function for
removing a node elsewhere--you should read about this function and the other functions of the toolkit.
Summary
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THE END
Presentation copyright 2010, Addison Wesley Longman,For use with Data Structures and Other Objects Using C++by Michael Main and Walter Savitch.
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