Create Single Linked List.c

C Program to Implement the Singly Linked List using Dynamic Memory Allocation.

Author: 0xRitesh

linked-list/Single Linked List.c

@@ -0,0 +1,286 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+struct node 
+{
+ int data;
+ int key;
+ struct node *next;
+};
+
+struct node *head = NULL;
+
+//display the list
+void printList()
+{
+ struct node *ptr = head;
+ printf("\n[ ");
+
+ //start from the beginning
+ while(ptr != NULL)
+ { 
+ printf("(%d,%d) ",ptr->key,ptr->data);
+ ptr = ptr->next;
+ }
+
+ printf(" ]");
+}
+
+//insert node at the first location
+void insertFirst(int key, int data)
+{
+ //create a link
+ struct node *link = (struct node*) malloc(sizeof(struct node));
+
+ link->key = key;
+ link->data = data;
+
+ //point it to old first node
+ link->next = head;
+
+ //point first to new first node
+ head = link;
+}
+
+//delete first item
+struct node* deleteFirst()
+{
+ //save reference to first link
+ struct node *tempLink = head;
+
+ //mark next to first link as first 
+ head = head->next;
+
+ //return the deleted link
+ return tempLink;
+}
+
+//is list empty
+bool isEmpty()
+{
+ return head == NULL;
+}
+
+//returns the length of the chain
+int length()
+{
+ int length = 0;
+ struct node *current;
+
+ for(current = head; current != NULL; current = current->next)
+ {
+ length++;
+ }
+
+ return length;
+}
+
+//find a link with given key
+struct node* find(int key)
+{
+
+ //start from the first link
+ struct node* current = head;
+
+ //if list is empty
+ if(head == NULL)
+ {
+ return NULL;
+ }
+
+ //navigate through list
+ while(current->key != key)
+ {
+ //if it is last node
+ if(current->next == NULL)
+ {
+ return NULL;
+ }
+ else 
+ {
+ //go to next link
+ current = current->next;
+ }
+ } 
+
+ //if data found, return the current Link
+ return current;
+}
+
+//delete a link with given key
+struct node* delete(int key)
+{
+
+ //start from the first link
+ struct node* current = head;
+ struct node* previous = NULL;
+
+ //if list is empty
+ if(head == NULL)
+ {
+ return NULL;
+ }
+
+ //navigate through list
+ while(current->key != key)
+ {
+
+ //if it is last node
+ if(current->next == NULL)
+ {
+ return NULL;
+ }
+ else 
+ {
+ //store reference to current link
+ previous = current;
+ //move to next link
+ current = current->next; 
+ }
+ }
+
+ //found a match, update the link
+ if(current == head) 
+ {
+ //change first to point to next link
+ head = head->next;
+ }
+ else 
+ {
+ //bypass the current link
+ previous->next = current->next;
+ } 
+
+ return current;
+}
+
+//sort the linked list
+void sort()
+{
+ int i, j, k, tempKey, tempData ;
+ struct node *current;
+ struct node *next;
+
+ int size = length();
+ k = size ;
+
+ for ( i = 0 ; i < size - 1 ; i++, k-- ) 
+ {
+ current = head ;
+ next = head->next ;
+
+ for ( j = 1 ; j < k ; j++ ) 
+ { 
+
+ if ( current->data > next->data ) 
+ {
+ tempData = current->data ;
+ current->data = next->data;
+ next->data = tempData ;
+
+ tempKey = current->key;
+ current->key = next->key;
+ next->key = tempKey;
+ }
+
+ current = current->next;
+ next = next->next; 
+ }
+ } 
+}
+
+//reverse the linked list
+void reverse(struct node** head_ref) 
+{
+ struct node* prev = NULL;
+ struct node* current = *head_ref;
+ struct node* next;
+
+ while (current != NULL) 
+ {
+ next = current->next; 
+ current->next = prev; 
+ prev = current;
+ current = next;
+ }
+
+ *head_ref = prev;
+}
+
+int main() 
+{
+ insertFirst(1,10);
+ insertFirst(2,20);
+ insertFirst(3,30);
+ insertFirst(4,1);
+ insertFirst(5,40);
+ insertFirst(6,56); 
+
+ printf("Original List: "); 
+
+ //print list
+ printList();
+
+ while(!isEmpty())
+ { 
+ struct node *temp = deleteFirst();
+ printf("\nDeleted value:"); 
+ printf("(%d,%d) ",temp->key,temp->data); 
+ } 
+
+ printf("\nList after deleting all items: "); 
+ printList();
+ insertFirst(1,10);
+ insertFirst(2,20);
+ insertFirst(3,30);
+ insertFirst(4,1);
+ insertFirst(5,40);
+ insertFirst(6,56); 
+ printf("\nRestored List: "); 
+ printList();
+ printf("\n"); 
+
+ struct node *foundLink = find(4);
+
+ if(foundLink != NULL)
+ {
+ printf("Element found: "); 
+ printf("(%d,%d) ",foundLink->key,foundLink->data); 
+ printf("\n"); 
+ }
+ else 
+ {
+ printf("Element not found."); 
+ }
+
+ delete(4);
+ printf("List after deleting an item: "); 
+ printList();
+ printf("\n");
+ foundLink = find(4);
+
+ if(foundLink != NULL)
+ {
+ printf("Element found: "); 
+ printf("(%d,%d) ",foundLink->key,foundLink->data); 
+ printf("\n"); 
+ }
+ else 
+ {
+ printf("Element not found."); 
+ }
+
+ printf("\n"); 
+ sort();
+
+ printf("List after sorting the data: "); 
+ printList();
+
+ reverse(&head);
+ printf("\nList after reversing the data: "); 
+ printList();
+
+ return 0;
+}