JACKlickd

Use this code however you want.

Source code of linked.h:

#ifndef LINKED_H
#define LINKED_H

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

typedef struct Node {
	int val;
	struct Node *next;
} Node;

typedef struct {
	Node *head;
} Linked_List;

Node *create_node(int);
Linked_List *create_linked_list();
void linked_list_add_at_head(Linked_List *, int);
void linked_list_add_at_tail(Linked_List *, int);
void linked_list_add_at_index(Linked_List *, int, int);
void linked_list_delete_at_index(Linked_List *, int);
void linked_list_free(Linked_List *);
int linked_list_get(Linked_List *, int);
void display(Linked_List *);

#endif

Source code of linked.c:

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

Node *create_node(int val){
	Node *node = (Node*)calloc(1, sizeof(Node));
	node->next = NULL;
	node->val = val;
	return node;
}

Linked_List *create_linked_list(){
	Linked_List *list = (Linked_List*)calloc(1, sizeof(Linked_List));
	list->head = NULL;
	return list;
}

void linked_list_add_at_head(Linked_List *list, int val){
	if(NULL == list->head)
		list->head = create_node(val);
	else{
		Node *temp = list->head;
		list->head = create_node(val);
		list->head->next = temp;
	}
}

void linked_list_add_at_tail(Linked_List *list, int val){
	Node *cur;
	if(!list->head)
		linked_list_add_at_head(list, val);
	else{
		cur = list->head;
		while(NULL != cur->next)
			cur = cur->next;
		cur->next = create_node(val);
	}
}

void linked_list_add_at_index(Linked_List *list, int index, int val){
	Node *cur = list->head;
	Node *temp;
	if(!index)
		linked_list_add_at_head(list, val);
	else if(index && cur){
		for(int i = 1; i < index; i++){
			if(cur->next)
				cur = cur->next;
			else
				return;
		}
		temp = cur->next;
		cur->next = create_node(val);
		cur = cur->next;
		cur->next = temp;
	}
}

void linked_list_delete_at_index(Linked_List *list, int index){
	Node *cur = list->head;
	Node *delete_node;

	if(!index && cur->next){
		list->head = cur->next;
		free(cur);
	}
	else if(!index && !cur->next)
		list->head = NULL;
	else if(cur->next){
		for(int i = 1; i < index; i++){
			if(cur->next->next)
				cur = cur->next;
			else
				return;
		}
		delete_node = cur->next;
		cur->next = delete_node->next;
		free(delete_node);
	}
}

void linked_list_free(Linked_List *list){
	Node *temp = list->head;
	Node *next;
	if(temp && temp->next){
		next = temp->next;
		free(temp);
		while(next->next){
			temp = next;
			next = next->next;
			free(temp);
		}
		free(next);
	}
	else if(temp)
		free(temp);
}

int linked_list_get(Linked_List *list, int index){
	Node *cur = list->head;
	if(!index && cur)
		return cur->val;
	else if(!index && !cur)
		return -1;
	else{
		for(int i = 0; i < index; i++){
			if(cur->next)
				cur = cur->next;
			else
				return -1;
		}
		return cur->val;
	}
}

void display(Linked_List *list){
	Node *cur = list->head;
	printf("Linked list: ");
	if(NULL == list->head){
		printf("NULL\n");
		return;
	}
	while(NULL != cur){
		printf("%d ", cur->val);
		cur = cur->next;
	}
	printf("\n");
}

Let`s test this.

source code of list.c:

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

int main(){
	Linked_List *list = create_linked_list();
	for(int i = 0; i < 10; i++)
		linked_list_add_at_tail(list, i*3);
	linked_list_add_at_index(list, 2, 2);
	display(list);
	linked_list_free(list);
	return 0;
}

We need to compile this:

gcc list.c linked.c -o list.exe

list.exe

>> Linked list: 0 3 2 6 9 12 15 18 21 24 27.