menu driven list management

emily.c

# include <stdio.h>
# include <stdlib.h>
# include <stdbool.h>
typedef struct Node{
	int data;
	struct Node *next;
} node;

node* create_node(int data){
	node *new_node = (node *)malloc(sizeof(node));
	new_node->data = data;
	new_node->next = NULL;
	return new_node;
}
void append(node **head, int data){
	node * new_node = create_node(data);
	if(*head == NULL){
		*head = new_node;
		return;
	}
	node *tmp = *head;
	while(tmp -> next != NULL){
		tmp = tmp->next;
	}
	tmp->next = new_node;
}

void push(node **head, int data){
	node *new_node = create_node(data);
	new_node->next = *head;
	*head = new_node;
}

void print_list(node *head){
	if(head == NULL){
		printf("The list is empty\n");
		return;
	}
	while(head != NULL){
		printf("%d ", head->data);
		head = head->next;
	}
	printf("\n");
}

void insert_before(node **head, int target, int data){
	node *new_node = create_node(data);
	if(*head == NULL){
		printf("The list is empty\n");
		return;
	}
	if((*head)->data == target){
		push(&(*head), data);
		return;
	}
	node *prev = NULL, *curr = *head;
	while(curr != NULL && curr->data != target){
		prev = curr;
		curr = curr->next;
	}
	if(curr == NULL){
		printf("Value not found in the list\n");
		printf("The linked list after insertion before a value is:\n");
		print_list(*head);
		free(new_node);
		return;
	}
	prev -> next = new_node;
	new_node->next = curr;
	printf("The linked list after insertion before a value is:\n");
	print_list(*head);
}

void insert_after(node **head, int target, int data){
	node *tmp = *head;

	while(tmp != NULL && tmp->data != target)
		tmp = tmp->next;
	if (tmp != NULL) {
		node *new_node = create_node(data);	
		new_node->next = tmp->next;
		tmp->next = new_node;
	}else {
		printf("Value not found in the list\n");
		printf("The linked list after insertion after a value is:\n");
		print_list(*head);
		return;
	}
	printf("The linked list after insertion after a value is:\n");
	print_list(*head);
}

void delete_front(node **head){
	if (*head == NULL) {
		printf("List is empty\n");	
		return;
	}
	node *tmp = *head;
	(*head) = (*head)->next;
	free(tmp);
	printf("The linked list after deletion from the beginning is:\n");
	print_list(*head);

}
void delete_end(node **head){
	if (*head == NULL) {
		printf("List is empty\n");	
		return;
	}
	if((*head)->next == NULL){
		free(*head);
		*head = NULL;
		return;
	}
	node *tmp = *head, *prev = NULL;

	while(tmp->next != NULL){
		prev = tmp;
		tmp = tmp->next;
	}
	prev->next = NULL;
	free(tmp);
	printf("The linked list after deletion from the end is:\n");
	print_list(*head);
}

void delete_before(node **head, int target){
	if (*head == NULL || (*head)->next == NULL || (*head)->next->next == NULL) {
		printf("Value not found in the list\n");
		printf("The linked list after deletion before a value is:\n");
		print_list(*head);
		return;
	}	

	node *thirdLast = NULL, *secondLast = *head, *last = secondLast->next, *curr = last->next;

	while (curr != NULL && curr->data != target) {
		thirdLast = secondLast;
		secondLast = last;
		last = curr;
		curr = curr->next;
	}
	if (curr == NULL) {
		printf("Value not found in the list\n");
		printf("The linked list after deletion before a value is:\n");
		print_list(*head);
		return;
	}	
	if(thirdLast == NULL){
		*head = secondLast->next;
		free(secondLast);
	}else{
		thirdLast->next = last;
		free(secondLast);			
	}

	printf("The linked list after deletion before a value is:\n");
	print_list(*head);
}

void delete_after(node **head, int target){
	if (*head == NULL) {
		printf("Value not found in the list\n");
		printf("The linked list after deletion after a value is:\n");
		print_list(*head);
		return;
	}
	node *tmp = *head;
	while(tmp != NULL && tmp->data != target)
		tmp = tmp->next;

	if (tmp == NULL || tmp->next == NULL) {
		printf("Value not found in the list\n");
		printf("The linked list after deletion after a value is:\n");
		print_list(*head);
		return;
	}
	node *to_delete = tmp->next;
	tmp->next = tmp->next->next;
	free(to_delete);
	printf("The linked list after deletion after a value is:\n");
	print_list(*head);
}

int main(){
	node *nums = NULL;
	int ch, target, value;
	do {
		scanf("%d", &ch);	
		switch (ch) {
			case 1:
				int n = 0;
				while (true) {
					scanf("%d", &n);
					if(n == -1)
						break;
					append(&nums, n);
				}
				printf("LINKED LIST CREATED\n");
				break;
			case 2:
				print_list(nums);
				break;
			case 3:
				scanf("%d", &value);
				push(&nums, value);
				printf("The linked list after insertion at the beginning is:\n");
				print_list(nums);
				break;
			case 4:
				scanf("%d", &value);
				append(&nums, value);
				printf("The linked list after insertion at the end is:\n");
				print_list(nums);
				break;
			case 5:
				scanf("%d", &target);
				scanf("%d", &value);
				insert_before(&nums, target, value);
				break;
			case 6:
				scanf("%d", &target);
				scanf("%d", &value);
				insert_after(&nums, target, value);
				break;
			case 7:
				delete_front(&nums);
				break;
			case 8:
				delete_end(&nums);
				break;
			case 9:
				scanf("%d", &target);
				delete_before(&nums, target);
				break;
			case 10:
				scanf("%d", &target);
				delete_after(&nums, target);
				break;
			case 11:
				free(nums);
				break;
			default:
				printf("Invalid option! Please try again\n");
		}
	}while (ch != 11);
}