Single Linked list and its basic operations with traversing implementation

The article describes the single linked list ADT and its traversal implementation.
Submitted by Radib Kar, on October 21, 2018

Single linked list

Single linked list contains a number of nodes where each node has a data field and a pointer to next node. The link of the last node is to NULL, indicates end of list.

Single linked list structure

The node in the linked list can be created using struct.

struct node{
	// data field, can be of various type, here integer
	int data; 
	// pointer to next node
	struct node* next; 
};

Basic operations on linked list

Traversing
Inserting node
Deleting node

Traversing technique for a single linked list

Follow the pointers
Display content of current nodes
Stop when next pointer is NULL

C code to traverse a linked list and count number of nodes

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

struct node{
	int data; // data field
	struct node *next;
};

void traverse(struct node* head){
	struct node* current=head; // current node set to head
	int count=0; // to count total no of nodes
	printf("\n traversing the list\n");
	
	//traverse until current node isn't NULL
	while(current!=NULL){ 
		count++; //increase node count
		printf("%d ",current->data);
		current=current->next; // go to next node
	}
	printf("\ntotal no of nodes : %d\n",count);
}

struct node* creatnode(int d){
	struct node* temp= (struct node*) malloc(sizeof(struct node));
	temp->data=d;
	temp->next=NULL;
	return temp;
}

int main()
{
	printf("creating & traversing linked list\n");
	
	//same linked list is built according to image shown
	struct node* head=creatnode(5);
	
	head->next=creatnode(10);
	head->next->next=creatnode(20);
	head->next->next->next=creatnode(1);

	traverse(head);
	return 0;
}

Output

creating & traversing linked list

traversing the list
5 10 20 1
total no of nodes : 4

Time complexity:

O(n), for scanning the list of size n

Space complexity:

O(1), no additional memory required