C Exercises: Delete node from any position of a doubly linked list
9. Delete from Any Position in Doubly Linked List
Write a program in C to delete a node from any position in a doubly linked list.
Visual Presentation:
Sample Solution:
C Code:
#include <stdio.h>
#include <stdlib.h>
struct node {
int num;
struct node *preptr;
struct node *nextptr;
} *stnode, *ennode;
// Function prototypes
void DlListcreation(int n);
void DlListDeleteFirstNode();
void DlListDeleteLastNode();
void DlListDeleteAnyNode(int pos);
void displayDlList(int a);
int main() {
int n, a, insPlc;
stnode = NULL;
ennode = NULL;
// User input for the number of nodes
printf("\n\n Doubly Linked List : Delete node from any position of a doubly linked list :\n");
printf("----------------------------------------------------------------------------------\n");
printf(" Input the number of nodes (3 or more ): ");
scanf("%d", &n);
// Creating the doubly linked list
DlListcreation(n);
a = 1;
displayDlList(a);
// Asking for the position to delete a node
printf(" Input the position ( 1 to %d ) to delete a node : ", n);
scanf("%d", &insPlc);
// Checking for valid position and deleting the node
if (insPlc < 1 || insPlc > n) {
printf("\n Invalid position. Try again.\n ");
} else if (insPlc >= 1 && insPlc <= n) {
DlListDeleteAnyNode(insPlc);
a = 2;
displayDlList(a);
}
return 0;
}
// Function to create a doubly linked list
void DlListcreation(int n) {
int i, num;
struct node *fnNode;
if (n >= 1) {
// Allocating memory for the first node
stnode = (struct node *)malloc(sizeof(struct node));
if (stnode != NULL) {
// Input data for the first node
printf(" Input data for node 1 : ");
scanf("%d", &num);
stnode->num = num;
stnode->preptr = NULL;
stnode->nextptr = NULL;
ennode = stnode;
// Loop to create subsequent nodes and link them
for (i = 2; i <= n; i++) {
fnNode = (struct node *)malloc(sizeof(struct node));
if (fnNode != NULL) {
printf(" Input data for node %d : ", i);
scanf("%d", &num);
fnNode->num = num;
fnNode->preptr = ennode; // Linking new node with the previous node
fnNode->nextptr = NULL; // Setting next address of fnNode as NULL
ennode->nextptr = fnNode; // Linking previous node with the new node
ennode = fnNode; // Assigning new node as last node
} else {
printf(" Memory can not be allocated.");
break;
}
}
} else {
printf(" Memory can not be allocated.");
}
}
}
// Function to delete a node from any position in the doubly linked list
void DlListDeleteAnyNode(int pos) {
struct node *curNode;
int i;
curNode = stnode;
for (i = 1; i < pos && curNode != NULL; i++) {
curNode = curNode->nextptr;
}
if (pos == 1) {
DlListDeleteFirstNode();
} else if (curNode == ennode) {
DlListDeleteLastNode();
} else if (curNode != NULL) {
curNode->preptr->nextptr = curNode->nextptr;
curNode->nextptr->preptr = curNode->preptr;
free(curNode); // Delete the n node
} else {
printf(" The given position is invalid!\n");
}
}
// Function to delete the first node from the doubly linked list
void DlListDeleteFirstNode() {
struct node *NodeToDel;
if (stnode == NULL) {
printf(" Delete is not possible. No data in the list.\n");
} else {
NodeToDel = stnode;
stnode = stnode->nextptr; // Move the next address of starting node to 2 node
stnode->preptr = NULL; // Set previous address of starting node to NULL
free(NodeToDel); // Delete the first node from memory
}
}
// Function to delete the last node from the doubly linked list
void DlListDeleteLastNode() {
struct node *NodeToDel;
if (ennode == NULL) {
printf(" Delete is not possible. No data in the list.\n");
} else {
NodeToDel = ennode;
ennode = ennode->preptr; // Move the previous address of the last node to 2nd last node
ennode->nextptr = NULL; // Set the next address of last node to NULL
free(NodeToDel); // Delete the last node
}
}
// Function to display the doubly linked list
void displayDlList(int m) {
struct node *tmp;
int n = 1;
if (stnode == NULL) {
printf(" No data found in the List yet.");
} else {
tmp = stnode;
if (m == 1) {
printf("\n Data entered in the list are :\n");
} else {
printf("\n After deletion the new list are :\n");
}
// Loop to display nodes and their data
while (tmp != NULL) {
printf(" node %d : %d\n", n, tmp->num);
n++;
tmp = tmp->nextptr; // Moving the current pointer to the next node
}
}
}
Sample Output:
Doubly Linked List : Delete node from any position of a doubly linked list :
----------------------------------------------------------------------------------
Input the number of nodes (3 or more ): 3
Input data for node 1 : 1
Input data for node 2 : 2
Input data for node 3 : 3
Data entered in the list are :
node 1 : 1
node 2 : 2
node 3 : 3
Input the position ( 1 to 3 ) to delete a node : 3
After deletion the new list are :
node 1 : 1
node 2 : 2
Flowchart:
DlListcreation() :
DlListDeleteAnyNode() :
DlListDeleteFirstNode() :
DlListDeleteLastNode() :
displayDlList() :
For more Practice: Solve these Related Problems:
- Write a C program to delete a node from a specified position in a doubly linked list with comprehensive error checking.
- Write a C program to remove a node at any given position in a doubly linked list and display the list from both directions.
- Write a C program to delete a node from a doubly linked list using recursion to locate and remove the target node.
- Write a C program to delete a node from any position and then re-adjust the pointers to optimize memory usage.
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