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Link List implementation of Stack


In this post, we will implement the stack using link list. First we define a node for link list as below: 

struct node{
 int info;
 struct node *next;
};
typedef struct node NODE;
In the above code info hold the value stored in stack and next is pointer to next node in the list.  

Push Operation:

Now we will implement the push operation on the stack above defined. Let us see the code for push operation: 

void push(NODE **start, int n){
 NODE *ptr = getNode();
 ptr->info = n;
 ptr->next = *start;
 *start = ptr;
}
 

Pop Operation:

Now we will implement the pop operation on the stack above defined. Let us see the code for push operation: 

int pop(NODE **start){
 NODE *temp = *start;
 int info;
 if(*start == NULL){
  printf("\nNo element exists in the stack\n");
 }
 else{
  *start = (*start)->next;
  info = temp->info;
  free(temp);
  return info;
 }
}
 

Program to implement stack using link list:

Here is the complete implementation of stack using link list: 

#include <stdio.h>
#include <malloc.h>

struct node{
 int info;
 struct node *next;
};
typedef struct node NODE;


NODE* getNode();
void push(NODE **, int);
int pop(NODE **);
void traverse(NODE **);

int main(){
 
 NODE *top = NULL;
 push(&top, 1);
 push(&top, 2);
 traverse(&top);
 pop(&top);
 traverse(&top);
 pop(&top);
 pop(&top);
 return 0;
}


int pop(NODE **start){
 NODE *temp = *start;
 int info;
 if(*start == NULL){
  printf("\nNo element exists in the stack\n");
 }
 else{
  *start = (*start)->next;
  info = temp->info;
  free(temp);
  return info;
 }
}

void push(NODE **start, int n){
 NODE *ptr = getNode();
 ptr->info = n;
 ptr->next = *start;
 *start = ptr;
}

void traverse(NODE **start){
 NODE *temp;
 temp = *start;
 while(temp != NULL){
  printf("%d  ", temp->info);
  temp = temp->next;
 }
 printf("\n");
}

NODE* getNode(){
 return (NODE*) malloc(sizeof(NODE));
}
 
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