Display Numbers in Reverse Order Using Single Linked List in C

Linked lists use dynamic memory allocation and are collection of nodes.

Nodes have two parts which are data and link.

Types of Linked Lists

The types of linked lists in C programming language are as follows −

• Single / Singly linked lists
• Double / Doubly linked lists
• Circular single linked list
• Circular double linked list

Single linked list

The diagram given below depicts the representation of single linked list.

Example

Following is the C program to display the numbers in reverse order by using the single linked list −

 Live Demo

#include <stdio.h>
#include <stdlib.h>
struct node {
   int num;
   struct node *nextptr;
}*stnode;
void createNodeList(int n);
void reverseDispList();
void displayList();
int main(){
   int n;
   printf("

 single Linked List : print it in reverse order :
");
   printf("------------------------------------------------------------------------------
");
   printf(" Input the number of nodes : ");
   scanf("%d", &n);
   createNodeList(n);
   printf("
 Data entered in the list are : 
");
   displayList();
   reverseDispList();
   printf("
 The list in reverse are : 
");
   displayList();
   return 0;
}
void createNodeList(int n){
   struct node *fnNode, *tmp;
   int num, i;
   stnode = (struct node *)malloc(sizeof(struct node));
   if(stnode == NULL) {
      printf(" Memory can not be allocated.");
   }
   else{
      // reads data for the node through keyboard
      printf(" Input data for node 1 : ");
      scanf("%d", &num);
      stnode-> num = num;
      stnode-> nextptr = NULL;
      tmp = stnode;
      //Creates n nodes and adds to linked list
      for(i=2; i<=n; i++){
         fnNode = (struct node *)malloc(sizeof(struct node));
         if(fnNode == NULL) {
            printf(" Memory can not be allocated.");
            break;
         }
         else{
            printf(" Input data for node %d : ", i);
            scanf(" %d", &num);
            fnNode->num = num;
            fnNode->nextptr = NULL;
            tmp->nextptr = fnNode;
            tmp = tmp->nextptr;
         }
      }
   }
}
void reverseDispList(){
   struct node *prevNode, *curNode;
   if(stnode != NULL){
      prevNode = stnode;
      curNode = stnode->nextptr;
      stnode = stnode->nextptr;
      prevNode->nextptr = NULL; //convert the first node as last
      while(stnode != NULL){
         stnode = stnode->nextptr;
         curNode->nextptr = prevNode;
         prevNode = curNode;
         curNode = stnode;
      }
      stnode = prevNode; //convert the last node as head
   }
}
void displayList(){
   struct node *tmp;
   if(stnode == NULL){
      printf(" No data found in the list.");
   }
   else{
      tmp = stnode;
      while(tmp != NULL){
         printf(" Data = %d
", tmp->num);
         tmp = tmp->nextptr;
      }
   }
}

Output

When the above program is executed, it produces the following result −

Single Linked List : print it in reverse order :
------------------------------------------------------------------------------
Input the number of nodes : 5
Input data for node 1 : 12
Input data for node 2 : 45
Input data for node 3 : 11
Input data for node 4 : 9
Input data for node 5 : 10

Data entered in the list are :
Data = 12
Data = 45
Data = 11
Data = 9
Data = 10

The list in reverse are :
Data = 10
Data = 9
Data = 11
Data = 45
Data = 12