learn.c

// Include Standard IO Library. 
#include <stdio.h>
// Include Standard bool Library. 
#include <stdbool.h>
// STDlib is required because we are using malloc()
#include <stdlib.h>

// Creating a data structure called Node = a single node in the list.
struct Node {
	int data;
	struct Node* next;
};

void printList(struct Node *node) {
	printf("Contents of the list: \n");
	while(node != NULL){
		printf("Data: %d \n", node->data);
		node=node->next;
	}
}

// Add a new item to the end of our linked list. 
//function append(struct Node** node, int value) {
//}


/* Given a node prev_node, insert a new node after the given
   prev_node */
struct Node* insert(struct Node* prev_node, int new_data)
{
	/* 1. check if the given prev_node is NULL */
	if (prev_node == NULL)
	{
		printf("the given previous node cannot be NULL");
		return NULL;
	}

	/* 2. allocate new node */
	struct Node* new_node =(struct Node*) malloc(sizeof(struct Node));

	/* 3. put in the data  */
	new_node->data  = new_data;

	/* 4. Make next of new node as next of prev_node */
	new_node->next = prev_node->next;

	/* 5. move the next of prev_node as new_node */
	prev_node->next = new_node;
	return new_node;
}

int main() {
	// Declare 3 nodes in our linked list.
	struct Node* head = NULL;

	// Allocate memory in C for our 3 nodes. 
	head = (struct Node*)malloc(sizeof(struct Node));
	// Set the value of the first item in the list.
	head->data = 25;
	head->next = NULL;

	// Insert second
	struct Node* second = insert(head, 30);

	// Insert third
	struct Node* third = insert(second, 32);

	struct Node* fourth = insert(third, 45);
	struct Node* fifth = insert(fourth, 49);

	insert(fifth, 700);

	printList(head);

	return 0;
}