Now that you have got an understanding of the basic concepts behind linked list and their types, its time to dive into the common operations that can be performed.
Two important points to remember:
In all of the examples, we will assume that the linked list has three nodes 1 --->2 --->3 with node structure as below:
struct node
{
int data;
struct node *next;
};
Displaying the contents of a linked list is very simple. We keep moving the temp node to the next one and display its contents.
When temp is NULL, we know that we have reached the end of linked list so we get out of the while loop.
struct node *temp = head;
printf("\n\nList elements are - \n");
while(temp != NULL)
{
printf("%d --->",temp->data);
temp = temp->next;
}
The output of this program will be:
List elements are - 1 --->2 --->3 --->
You can add elements to either beginning, middle or end of linked list.
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = 4;
newNode->next = head;
head = newNode;
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = 4;
newNode->next = NULL;
struct node *temp = head;
while(temp->next != NULL){
temp = temp->next;
}
temp->next = newNode;
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = 4;
struct node *temp = head;
for(int i=2; i < position; i++) {
if(temp->next != NULL) {
temp = temp->next;
}
}
newNode->next = temp->next;
temp->next = newNode;
You can delete either from beginning, end or from a particular position.
head = head->next;
struct node* temp = head;
while(temp->next->next!=NULL){
temp = temp->next;
}
temp->next = NULL;
for(int i=2; i< position; i++) {
if(temp->next!=NULL) {
temp = temp->next;
}
}
temp->next = temp->next->next;
Here is the complete program for all the linked list operations we learnt till now. Lots of edge cases have been left out to make the program short.
We suggest you to just have a look at the program and try to implement it yourself.
Also, notice how we pass address of head as struct node **headRef in the functions insertAtFront and deleteFromFront. These two functions change the position of head pointer so we need to pass the address of head pointer and change its value within the function.
#include<stdio.h>
#include<stdlib.h>
struct node
{
int data;
struct node *next;
};
void display(struct node* head)
{
struct node *temp = head;
printf("\n\nList elements are - \n");
while(temp != NULL)
{
printf("%d --->",temp->data);
temp = temp->next;
}
}
void insertAtMiddle(struct node *head, int position, int value) {
struct node *temp = head;
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = value;
int i;
for(i=2; inext != NULL) {
temp = temp->next;
}
}
newNode->next = temp->next;
temp->next = newNode;
}
void insertAtFront(struct node** headRef, int value) {
struct node* head = *headRef;
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = value;
newNode->next = head;
head = newNode;
*headRef = head;
}
void insertAtEnd(struct node* head, int value){
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = value;
newNode->next = NULL;
struct node *temp = head;
while(temp->next != NULL){
temp = temp->next;
}
temp->next = newNode;
}
void deleteFromFront(struct node** headRef){
struct node* head = *headRef;
head = head->next;
*headRef = head;
}
void deleteFromEnd(struct node* head){
struct node* temp = head;
while(temp->next->next!=NULL){
temp = temp->next;
}
temp->next = NULL;
}
void deleteFromMiddle(struct node* head, int position){
struct node* temp = head;
int i;
for(i=2; inext != NULL) {
temp = temp->next;
}
}
temp->next = temp->next->next;
}
int main() {
/* Initialize nodes */
struct node *head;
struct node *one = NULL;
struct node *two = NULL;
struct node *three = NULL;
/* Allocate memory */
one = malloc(sizeof(struct node));
two = malloc(sizeof(struct node));
three = malloc(sizeof(struct node));
/* Assign data values */
one->data = 1;
two->data = 2;
three->data = 3;
/* Connect nodes */
one->next = two;
two->next = three;
three->next = NULL;
/* Save address of first node in head */
head = one;
display(head); // 1 --->2 --->3 --->
insertAtFront(&head, 4);
display(head); // 4 --->1 --->2 --->3 --->
deleteFromFront(&head);
display(head); // 1 --->2 --->3 --->
insertAtEnd(head, 5);
display(head); // 1 --->2 --->3 --->5 --->
deleteFromEnd(head);
display(head); // 1 --->2 --->3 --->
int position = 3;
insertAtMiddle(head, position, 10);
display(head); // 1 --->2 --->10 --->3 --->
deleteFromMiddle(head, position);
display(head); // 1 --->2 --->3 --->
}
The output of the above program is
List elements are -
1 --->2 --->3 --->
List elements are -
4 --->1 --->2 --->3 --->
List elements are -
1 --->2 --->3 --->
List elements are -
1 --->2 --->3 --->5 --->
List elements are -
1 --->2 --->3 --->
List elements are -
1 --->2 --->10 --->3 --->
List elements are - 1 --->2 --->3 --->