stack implementation using linked list

About Linked list

A linked list is a way to store a collection of elements. Like an array, these can be character or integers. Each element in a linked list is stored in the form of a node.

Declaring a Stack

In C language, a stack list can be implemented using structure and pointers, it’s simpler to single linked list.

struct STACK
{
  int data;
  struct STACK*next;
};
struct STACK*top=NULL;
typedef struct STACK stack;

Stack Push Operation

Push, Its a simple process to insert or add a new element to stack using linked list add node approach.

void push()
{
  stack*ttop;
  int data;
  if(top==NULL)
  {
    top=(stack*)malloc(sizeof(stack));
    printf("\nEnter data: ");
    scanf("%d",&data);
    //scanf("%d",&top->data);
    top->data=data;
    top->next=NULL;
    return;
  }
  else
  {
    ttop=(stack*)malloc(sizeof(stack));
    printf("\nEnter Data: ");
    scanf("%d",&data);
    ttop->data=data;
    ttop->next=top;
    top=ttop;
    return;
  }
}

Stack Pop Operation

Pop, It’s a simple process to delete or remove a new element to stack using linked list delete node approach.

void pop()
{
  stack*ttop;
  if(top==NULL)
  {
   printf("\nSTACK UNDERFLOW(EMPTY): ");
   return;
  }
  else
  {
   ttop=top;
   top=top->next;
   ttop->next=NULL;
   printf("\ndeleted data:%d",ttop->data);
   free(ttop);
   return;
  }
}

Stack Peek Operation

Peek, It’s a simple process to display or traversal operation on Stack without deleting an element 

void peek()
{
  stack*ttop;
  if(top==NULL)
  {
   printf("\nSTACK IS EMPTY");
   return;
  }
  printf("\nSTACK DATA: ");
  ttop=top;
  do
  {
   printf("%d ",ttop->data);
   ttop=ttop->next;
  }while(ttop!=NULL);
  return;
}

main() function Implementation 

int main()
{
  int option;
  while(1)
  {
   clrscr();
   printf("\n1.FOR PUSH : ");
   printf("\n2.FOR POP  : ");
   printf("\n3.FOR PEEK : ");
   printf("\n4.FOR EXIT : ");
   scanf("%d",&option);
   switch(option)
   {
    case 1: push();
          break;
    case 2: pop();
          break;
    case 3: peek();
          break;
    case 4: free(top);
          top=NULL;
          return 0;

    default: printf("\nInvalid Option: ");
   }
    }
    return 0;
}