C program to create and traverse Singly Linked List

Required knowledge:

Algorithm to create Singly linked list:

Algorithm to create Singly Linked List
Begin:
    alloc (head)
    If (head == NULL) then
        write ('Unable to allocate memory')
    End if
    Else
        read (data)
        head.data ← data;
        head.next ← NULL;
    End if
End

Algorithm to display or traverse singly linked list:

Algorithm to traverse Singly Linked List
%% head contains the address of head node
Begin:
    If (head == NULL) then
        write ('List is empty')
    End if
    Else
        temp ← head;
        While (temp != NULL) do
            write ('Data = ' + temp.data)
            temp ← temp.next;
        End while
    End if
End

Program:

/**
 * C program to create and display Singly Linked List
 */

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

/* Structure of a node */
struct node {
    int data; //Data part
    struct node *next; //Address part
}*head;


/* 
 * Functions to create and display list
 */
void createList(int n);
void traverseList();


int main()
{
    int n;

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

    createList(n);

    printf("\nData in the list \n");
    traverseList();

    return 0;
}

/*
 * Create a list of n nodes
 */
void createList(int n)
{
    struct node *newNode, *temp;
    int data, i;

    head = (struct node *)malloc(sizeof(struct node));

    /*
     * If unable to allocate memory for head node
     */
    if(head == NULL)
    {
        printf("Unable to allocate memory.");
    }
    else
    {
        /*
         * Reads data of node from the user
         */
        printf("Enter the data of node 1: ");
        scanf("%d", &data);

        head->data = data; //Links the data field with data
        head->next = NULL; //Links the address field to NULL

        temp = head;

        /*
         * Creates n nodes and adds to linked list
         */
        for(i=2; i<=n; i++)
        {
            newNode = (struct node *)malloc(sizeof(struct node));

            /* If memory is not allocated for newNode */
            if(newNode == NULL)
            {
                printf("Unable to allocate memory.");
                break;
            }
            else
            {
                printf("Enter the data of node %d: ", i);
                scanf("%d", &data);

                newNode->data = data; //Links the data field of newNode with data
                newNode->next = NULL; //Links the address field of newNode with NULL

                temp->next = newNode; //Links previous node i.e. temp to the newNode
                temp = temp->next; 
            }
        }
    }
}

/*
 * Displays the entire list
 */
void traverseList()
{
    struct node *temp;

    /*
     * If the list is empty i.e. head = NULL
     */
    if(head == NULL)
    {
        printf("List is empty.");
    }
    else
    {
        temp = head;
        while(temp != NULL)
        {
            printf("Data = %d\n", temp->data); //Prints the data of current node
            temp = temp->next; //Advances the position of current node
        }
    }
}