A simple and explained code on singly linked list.

singly-linked-list.c

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

struct list {
	int value;
	struct list* next;
};

struct list* root = NULL;
struct list* lastNodeAddr = NULL;

struct list* nodeCreation(int value) {
	struct list* temp = (struct list*) malloc(sizeof(struct list));
	temp->value = value;
	temp->next = NULL;
	return temp;
}

void insertInTheList(struct list* temp) {
	if(root == NULL) {
		root = temp;
		lastNodeAddr = root;
	} else {
		lastNodeAddr->next = temp;
		lastNodeAddr = temp;
	}
}

void showTheList(struct list* head) {
	if(root == NULL) {
		printf("List is empty!\n");
		return;
	}	
	while(head != NULL) {
		printf("->%d\n", head->value);
		head = head->next;
	}
}

void destroyTheList(struct list* head) {	
	if(head != NULL) {
		destroyTheList(head->next);
		if(root == head) {
			root = NULL;
		} else {
			free(head);	
		}		
	}
}

void deleteTheNode(int deleteValue) {
	struct list* iterator = root;
	struct list* previousNode = root;
	while(iterator != NULL) {
		if(iterator->value == deleteValue) {			
			if(iterator->next == NULL) {
				previousNode->next = NULL;				
			} else {
				previousNode->next = iterator->next;	
			}
			if(previousNode == root) {
				root = iterator->next;
			}
			if(lastNodeAddr == iterator) {				
				lastNodeAddr = previousNode;
			}
			struct list* temporaryHolder = iterator;
			iterator = iterator->next;
			free(temporaryHolder);
		} else {
			previousNode = iterator;
			iterator = iterator->next;
		}		
	}	
}

int main() {
	int choice;
	int localVal = 0;
	int deleteChoice = -1;
	int deleteNode = 0;
	while(1) {
		printf("1.Insert a Node\n2.show the list\n3.Deletion\n");
		scanf("%d",&choice);
		switch(choice) {
			case 1:				
				printf("Enter the Number: ");
				scanf("%d", &localVal);
				insertInTheList(nodeCreation(localVal));
				break;
			case 2:
				showTheList(root);
				break;
			case 3:
				printf("Do you want to delete the entire List or a Node ? 1 : 0 ");
				scanf("%d", &deleteChoice);
				if(deleteChoice) {
					if(root == NULL) 
						printf("List is empty!\n");
					else
						destroyTheList(root);
				} else {
					if(root == NULL) {
						printf("List is empty!\n");
						break;
					}						
					printf("Enter the Number in the Node");
					scanf("%d", &deleteNode);
					deleteTheNode(deleteNode);
				}
				break;			
			default:
				printf("wrong choice\n");
				destroyTheList(root);
				printf("Destroyed The list");
				exit(0);
		}
	}
	return 0;
}