﻿ C exercises: Delete the last node of Singly Linked List - w3resource

# C Exercises: Delete the last node of Singly Linked List

## C Linked List : Exercise-9 with Solution

Write a program in C to delete the last node of Singly Linked List.

Sample Solution:

C Code:

``````#include <stdio.h>
#include <stdlib.h>

struct node
{
int num;                    //Data of the node
struct node *nextptr;       //Address of the node
}*stnode;

void createNodeList(int n);     //function to create the list
void LastNodeDeletion();	    //function to delete the last nodes
void displayList();             //function to display the list

int main()
{
int n,num,pos;
printf("\n\n Linked List : Delete the last node of Singly Linked List :\n");
printf("---------------------------------------------------------------\n");

printf(" Input the number of nodes : ");
scanf("%d", &n);
createNodeList(n);

printf("\n Data entered in the list are : \n");
displayList();
LastNodeDeletion();
printf("\n The new list after deletion the last node are  : \n");
displayList();
return 0;
}
void createNodeList(int n)
{
struct node *fnNode, *tmp;
int num, i;

stnode = (struct node *)malloc(sizeof(struct node));
if(stnode == NULL) //check whether the stnode is NULL and if so no memory allocation
{
printf(" Memory can not be allocated.");
}
else
{
// reads data for the node through keyboard
printf(" Input data for node 1 : ");
scanf("%d", &num);

stnode-> num = num;
tmp = stnode;

for(i=2; i<=n; i++)
{
fnNode = (struct node *)malloc(sizeof(struct node));
if(fnNode == NULL) //check whether the fnnode is NULL and if so no memory allocation
{
printf(" Memory can not be allocated.");
break;
}
else
{
printf(" Input data for node %d : ", i);
scanf(" %d", &num);
fnNode->num = num;      // links the num field of fnNode with num
fnNode->nextptr = NULL; // links the address field of fnNode with NULL
tmp->nextptr = fnNode; // links previous node i.e. tmp to the fnNode
tmp = tmp->nextptr;
}
}
}
}
// Deletes the last node of the linked list
void LastNodeDeletion()
{
struct node *toDelLast, *preNode;
if(stnode == NULL)
{
printf(" There is no element in the list.");
}
else
{
toDelLast = stnode;
preNode = stnode;
/* Traverse to the last node of the list*/
while(toDelLast->nextptr != NULL)
{
preNode = toDelLast;
toDelLast = toDelLast->nextptr;
}
if(toDelLast == stnode)
{
stnode = NULL;
}
else
{

/* Disconnects the link of second last node with last node */
preNode->nextptr = NULL;
}

/* Delete the last node */
free(toDelLast);
}
}
// function to display the entire list
void displayList()
{
struct node *tmp;
if(stnode == NULL)
{
printf(" No data found in the empty list.");
}
else
{
tmp = stnode;
while(tmp != NULL)
{
printf(" Data = %d\n", tmp->num);   // prints the data of current node
tmp = tmp->nextptr;                 // advances the position of current node
}
}
}
```
```

Sample Output:

``` Linked List : Delete the last node of Singly Linked List :
---------------------------------------------------------------
Input the number of nodes : 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 :
Data = 1
Data = 2
Data = 3

The new list after deletion the last node are  :
Data = 1
Data = 2
```

Flowchart:

createNodeList() :

LastNodeDeletion() :

displayList() :

C Programming Code Editor:

```#include <stdio.h>
#include <stdlib.h>

struct node
{
int num;                    //Data of the node
struct node *nextptr;       //Address of the node
}*stnode;

void createNodeList(int n);     //function to create the list
void LastNodeDeletion();	    //function to delete the last nodes
void displayList();             //function to display the list

int main()
{
int n,num,pos;
printf("\n\n Linked List : Delete the last node of Singly Linked List :\n");
printf("---------------------------------------------------------------\n");

printf(" Input the number of nodes : ");
scanf("%d", &n);
createNodeList(n);

printf("\n Data entered in the list are : \n");
displayList();
LastNodeDeletion();
printf("\n The new list after deletion the last node are  : \n");
displayList();
return 0;
}
void createNodeList(int n)
{
struct node *fnNode, *tmp;
int num, i;

stnode = (struct node *)malloc(sizeof(struct node));
if(stnode == NULL) //check whether the stnode is NULL and if so no memory allocation
{
printf(" Memory can not be allocated.");
}
else
{
// reads data for the node through keyboard
printf(" Input data for node 1 : ");
scanf("%d", &num);

stnode-> num = num;
tmp = stnode;

for(i=2; i<=n; i++)
{
fnNode = (struct node *)malloc(sizeof(struct node));
if(fnNode == NULL) //check whether the fnnode is NULL and if so no memory allocation
{
printf(" Memory can not be allocated.");
break;
}
else
{
printf(" Input data for node %d : ", i);
scanf(" %d", &num);
fnNode->num = num;      // links the num field of fnNode with num
fnNode->nextptr = NULL; // links the address field of fnNode with NULL
tmp->nextptr = fnNode; // links previous node i.e. tmp to the fnNode
tmp = tmp->nextptr;
}
}
}
}
// Deletes the last node of the linked list
void LastNodeDeletion()
{
struct node *toDelLast, *preNode;
if(stnode == NULL)
{
printf(" There is no element in the list.");
}
else
{
toDelLast = stnode;
preNode = stnode;
/* Traverse to the last node of the list*/
while(toDelLast->nextptr != NULL)
{
preNode = toDelLast;
toDelLast = toDelLast->nextptr;
}
if(toDelLast == stnode)
{
stnode = NULL;
}
else
{
/* Disconnects the link of second last node with last node */
preNode->nextptr = NULL;
}

/* Delete the last node */
free(toDelLast);
}
}
// function to display the entire list
void displayList()
{
struct node *tmp;
if(stnode == NULL)
{
printf(" No data found in the empty list.");
}
else
{
tmp = stnode;
while(tmp != NULL)
{
printf(" Data = %d\n", tmp->num);   // prints the data of current node
tmp = tmp->nextptr;                 // advances the position of current node
}
}
} ```

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