Now we will see how to insert a new node at the last position of doubly link list.
Algorithm for insertion at last position in doubly link list:
In this algorithm, START is pointer to first node of list and PTR is the node to be inserted at last. The steps are as follows:- Create new node PTR
- Set the info field of PTR
- Set PTR->NEXT = NULL
- If list is empty i.e. START == NULL
- Set START = PTR
- Set PTR->PREV = NULL
- Else
- Traverse the list for last node into TEMP pointer
- Set PTR->PREV = TEMP
- Set TEMP->NEXT = PTR
- End If;
Function to insert node at last position in doubly link list:
void insertAtLast(NODE **start, int info){
NODE *ptr = (NODE*) malloc(sizeof(NODE));
NODE *temp = *start;
ptr->info = info;
ptr->next = NULL;
if(*start == NULL){
*start = ptr;
ptr->prev = NULL;
}
else{
while(temp->next != NULL){
temp = temp->next;
}
ptr->prev = temp;
temp->next = ptr;
}
}
Program to insert at last position in the doubly link list:
#include <stdio.h>
#include <malloc.h>
typedef struct node{
int info;
struct node *next, *prev;
} NODE;
void insertAtLast(NODE **, int);
void traverse(NODE **);
int main(){
NODE *start = NULL;
insertAtLast(&start, 1);
insertAtLast(&start, 2);
insertAtLast(&start, 3);
traverse(&start);
return 0;
}
void insertAtLast(NODE **start, int info){
NODE *ptr = (NODE*) malloc(sizeof(NODE));
NODE *temp = *start;
ptr->info = info;
ptr->next = NULL;
if(*start == NULL){
*start = ptr;
ptr->prev = NULL;
}
else{
while(temp->next != NULL){
temp = temp->next;
}
ptr->prev = temp;
temp->next = ptr;
}
}
void traverse(NODE **start){
NODE *temp = *start;
while(temp != NULL){
printf("%d ", temp->info);
temp = temp->next;
}
}
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