C Program To Implement Circular Stack

Circular stack can be implemented using circular linked list where the insertion and deletion operations are performed at the front(head) of the circular linked list(stack).

See Also:

C Program For Array Implementation Of Queue
C Program For Array Implementation Of Stack
C Program For Linked List Implementation Of Stack
C Program For Linked List Implementation Of Queue
C Program For Double Ended Queue (Dequeue)
C Program To Implement Circular Stack
C Program To Implement Circular Queue

C Program To Implement Priority Queue

C Program for Circular stack Implementation Using Circular Linked List:

---

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

  struct cStackNode {
        int data;
        struct cStackNode *next;
  };

  struct cStackNode *head = NULL;

  struct cStackNode * createNode(int data) {
        struct cStackNode *newnode;
        newnode = (struct cStackNode *)malloc(sizeof (struct cStackNode));
        newnode->data = data;
        newnode->next = NULL;
  }

  /* Insert node into the stack */

  void push(int data) {

        struct cStackNode *newnode, *tmp;

        int tmpData;

        if (!head) {

                head = createNode(data);

                head->next = head;

        } else {

                /*

                 * swap the contents of newnode

                 * and temp.  Insert the newnode

                 * next to head.  It's equivalent

                 * to adding node at the front

                 */

                newnode = createNode(data);

                tmp = head->next;

                head->next = newnode;

                newnode->next = tmp;

                tmpData = newnode->data;

                newnode->data = head->data;

                head->data = tmpData;

        }

  }

  /* Delete node at the front */

  void pop() {

        struct cStackNode *tmp;

        int tmpdata;

        if (!head) {

                printf("Circular Stack is empty\n");

                return;

        }

        if (head->next == head) {

                free(head);

                head = NULL;

                return;

        }

        tmp = head->next;

        head->data = tmp->data;

        head->next = tmp->next;

        free(tmp);

  }

  /* Display the contents of the Circular stack */

  void display() {

        struct cStackNode *tmp = head;

        if (!head) {

                printf("Circular Stack is empty\n");

                return;

        }

        printf("%-3d", head->data);

        tmp = tmp->next;

        while (tmp != head) {

                printf("%-3d", tmp->data);

                tmp = tmp->next;

        }

        printf("\n");

        return;

  }

  int main() {

        int data, ch;

        while (1) {

                printf("1. Push   \t2.Pop\n");

                printf("3. Display\t4.Exit\n");

                printf("Please enter your choice:");

                scanf("%d", &ch);

                switch (ch) {

                        case 1:

                                printf("Enter the data to insert:");

                                scanf("%d", &data);

                                push(data);

                                break;

                        case 2:

                                pop();

                                break;

                        case 3:

                                display();

                                break;

                        case 4:

                                exit(0);

                        default:

                                printf("Please enter correct option\n");

                                break;

                }

        }

        return 0;

  }

  Output: (Circular Stack Example)

  jp@jp-VirtualBox:~/cpgms/data_structures$ ./a.out
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:1
  Enter the data to insert:10
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:1
  Enter the data to insert:20
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:1
  Enter the data to insert:30
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:3
  30 20 10 
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:2
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:3
  20 10 
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:2
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:3
  10 
  1. Push   2.Pop
  3. Display 4.Exit
  Please enter your choice:4