C Exercises: Delete a node from the middle of Singly Linked List

Last update on December 20 2024 13:18:54 (UTC/GMT +8 hours)

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

Visual Presentation:

C Exercises: Delete a node from the middle 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;                       // Pointer to the starting node

// Function prototypes
void createNodeList(int n);      // Function to create the linked list
void MiddleNodeDeletion(int pos); // Function to delete a node from the middle
void displayList();              // Function to display the list

// Main function
int main()
{
    int n, num, pos;
    printf("\n\n Linked List : Delete a node from the middle 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();

    printf("\n Input the position of node to delete : ");
    scanf("%d", &pos);

    if (pos <= 1 || pos >= n)
    {
        printf("\n Deletion can not be possible from that position.\n ");
    }
    if (pos > 1 && pos < n)
    {
        printf("\n Deletion completed successfully.\n ");
        MiddleNodeDeletion(pos);
    }

    printf("\n The new list are  : \n");
    displayList();
    return 0;
}

// Function to create a linked list with n nodes
void createNodeList(int n)
{
    struct node *fnNode, *tmp;
    int num, i;

    stnode = (struct node *)malloc(sizeof(struct node));
    if (stnode == NULL)             // Check whether stnode is NULL for memory allocation
    {
        printf(" Memory can not be allocated.");
    }
    else
    {
        printf(" Input data for node 1 : ");
        scanf("%d", &num);

        stnode->num = num;          // Assign data to the first node
        stnode->nextptr = NULL;     // Links the address field to NULL
        tmp = stnode;

        // Create n nodes and add to the linked list
        for (i = 2; i <= n; i++)
        {
            fnNode = (struct node *)malloc(sizeof(struct node));

            if (fnNode == NULL)    // Check whether fnNode is NULL for memory allocation
            {
                printf(" Memory can not be allocated.");
                break;
            }
            else
            {
                printf(" Input data for node %d : ", i);
                scanf(" %d", &num);

                fnNode->num = num;      // Assign data to the current node
                fnNode->nextptr = NULL; // Links the address field to NULL

                tmp->nextptr = fnNode; // Links previous node i.e. tmp to the fnNode
                tmp = tmp->nextptr;
            }
        }
    }
}

// Function to delete a node from the middle of the list at a specific position
void MiddleNodeDeletion(int pos)
{
    int i;
    struct node *toDelMid, *preNode;

    if (stnode == NULL)
    {
        printf(" There are no nodes in the List.");
    }
    else
    {
        toDelMid = stnode;
        preNode = stnode;

        // Traverse to the specified position in the list
        for (i = 2; i <= pos; i++)
        {
            preNode = toDelMid;
            toDelMid = toDelMid->nextptr;

            if (toDelMid == NULL)
                break;
        }
        if (toDelMid != NULL)
        {
            if (toDelMid == stnode)    // If the node to delete is the first node
                stnode = stnode->nextptr;

            preNode->nextptr = toDelMid->nextptr; // Adjust the pointers
            toDelMid->nextptr = NULL;
            free(toDelMid);           // Free memory of the deleted node
        }
        else
        {
            printf(" Deletion can not be possible from that position.");
        }
    }
}

// Function to display the linked list
void displayList()
{
    struct node *tmp;

    if (stnode == NULL)
    {
        printf(" No data found in the list.");
    }
    else
    {
        tmp = stnode;
        while (tmp != NULL)
        {
            printf(" Data = %d\n", tmp->num);   // Print the data of the current node
            tmp = tmp->nextptr;                 // Move to the next node
        }
    }
}

Sample Output:

Linked List : delete a node from the middle of Singly Linked List. :                                         
-------------------------------------------------------------------------                                     
 Input the number of nodes : 3                                                                                
 Input data for node 1 : 2                                                                                    
 Input data for node 2 : 5                                                                                    
 Input data for node 3 : 8                                                                                    
                                                                                                              
 Data entered in the list are :                                                                               
 Data = 2                                                                                                     
 Data = 5                                                                                                     
 Data = 8                                                                                                     
                                                                                                              
 Input the position of node to delete : 2                                                                     
                                                                                                              
 Deletion completed successfully.                                                                             
                                                                                                              
 The new list are  :                                                                                          
 Data = 2                                                                                                     
 Data = 8

Flowchart: