C program for linked list implementation of stack




#include <stdio.h>

#include <stdlib.h>

#include <limits.h>

 

// A structure to represent a stack

struct StackNode

{

    int data;

    struct StackNode* next;

};

 

struct StackNode* newNode(int data)

{

    struct StackNode* stackNode =

              (struct StackNode*) malloc(sizeof(struct StackNode));

    stackNode->data = data;

    stackNode->next = NULL;

    return stackNode;

}

 

int isEmpty(struct StackNode *root)

{

    return !root;

}

 

void push(struct StackNode** root, int data)

{

    struct StackNode* stackNode = newNode(data);

    stackNode->next = *root;

    *root = stackNode;

    printf("%d pushed to stack\n", data);

}

 

int pop(struct StackNode** root)

{

    if (isEmpty(*root))

        return INT_MIN;

    struct StackNode* temp = *root;

    *root = (*root)->next;

    int popped = temp->data;

    free(temp);

 

    return popped;

}

 

int peek(struct StackNode* root)

{

    if (isEmpty(root))

        return INT_MIN;

    return root->data;

}

 

int main()

{

    struct StackNode* root = NULL;

 

    push(&root, 10);

    push(&root, 20);

    push(&root, 30);

 

    printf("%d popped from stack\n", pop(&root));

 

    printf("Top element is %d\n", peek(root));

 

    return 0;

}

Output:

10 pushed to stack
20 pushed to stack
30 pushed to stack
30 popped from stack
Top element is 20