push_pop_display.c

// Implementation of Stack using Array :- 

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

#define SIZE 5

int top = -1, stack[SIZE];

void push();
void pop();
void show();
void peak();

int main() 
{
    int choice;

    while (1) 
    {
        printf("\nPerform Stack Operations :- ");
        printf("\n1. Push the element\n2. Pop the element\n3. Peek\n4. Display\n5. End");
        printf("\n\nEnter your choice: ");
        scanf("%d", &choice);

        switch (choice) 
        {
            case 1:
                push();
                break;
            case 2:
                pop();
                break;
            case 3:
                peak();
                break;
            case 4:
                show();
                break;
            case 5:
                exit(0);
            default:
                printf("\nInvalid Choice!!");
        }
    }
}

void push() 
{
    int x;
    if (top == SIZE - 1)
        printf("\nOverflow!! Cannot push element onto full stack.");
    else 
    {
        printf("\nEnter the element to be pushed onto the stack: ");
        scanf("%d", &x);
        top++;
        stack[top] = x;
        printf("Element %d pushed onto the stack.", x);
    }
}

void pop() 
{
    if (top == -1)
        printf("\nUnderflow!! Stack is empty.");
    else 
    {
        printf("\nElement %d popped from the stack.", stack[top]);
        top--;
    }
}

void peak() 
{
    if (top == -1)
        printf("\nUnderflow!! Stack is empty.");
    else
        printf("\nTop element of the stack: %d", stack[top]);
}

void show() 
{
    if (top == -1)
        printf("\nUnderflow!! Stack is empty.");
    else 
    {
        printf("\nElements present in the stack: \n");
        for (int i = top; i >= 0; i--)
            printf("%d\n", stack[i]);
    }
}

// ===================================================================================================== //

// Stack implementation using Linked List :-

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

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

struct Node* newNode(int data) 
{
    struct Node* node = (struct Node*)malloc(sizeof(struct Node));
    if (!node) 
    {
        printf("Memory allocation failed\n");
        exit(EXIT_FAILURE);
    }
    node->data = data;
    node->next = NULL;
    return node;
}

int isEmpty(struct Node* top)
{
    return (top == NULL);
}

void push(struct Node** top, int data) 
{
    struct Node* newNodePtr = newNode(data);
    newNodePtr->next = *top;
    *top = newNodePtr;
    printf("%d pushed to stack\n", data);
}

int pop(struct Node** top)
{
    if (isEmpty(*top)) 
    {
        printf("Stack is empty\n");
        exit(EXIT_FAILURE);
    }
    struct Node* temp = *top;
    int popped = temp->data;
    *top = temp->next;
    free(temp);
    return popped;
}

int peek(struct Node* top)
{
    if (isEmpty(top)) 
    {
        printf("Stack is empty\n");
        exit(EXIT_FAILURE);
    }
    return top->data;
}

void display(struct Node* top) 
{
    if (isEmpty(top)) 
    {
        printf("Stack is empty\n");
        return;
    }
    struct Node* temp = top;
    printf("Stack: ");
    while (temp != NULL) 
    {
        printf("%d ", temp->data);
        temp = temp->next;
    }
    printf("\n");
}

int main() 
{
    struct Node* top = NULL;

    push(&top, 1);
    push(&top, 2);
    push(&top, 3);
    push(&top, 4);

    display(top);

    printf("Peek: %d\n", peek(top));

    printf("Popped: %d\n", pop(&top));

    display(top);

    return 0;
}

// =================================================================================================================== //